——— D ———

DAB (Digital Audio Broadcast) – a technology for digital broadcasting by radio stations. It has been essentially replaced by DAB+. See HD radio and DAR.

DAB+ – an improved version of digital broadcasting (DAB). DAB+ makes much more efficient use of the available bandwidth used for digitaltransmitting radio signals. DAB+ stations can transmit up to three times as much data as DAB, providing higher quality audio for listeners and greater space for more stations. DAB+ has more reliable reception than standard digital radio, so that signal loss is much more unlikely. It is broadcast on different frequencies from standard AM and FM stations. DAB+ is the most widely adopted digital radio standard worldwide, being used in more than 40 countries around the world, but not yet in the US.

D/A – Digital-to-Analog. See Digital-to-Analog conversion. Also written as DA or D-A.

da capo – a musical term, literally meaning “from the head,” which instructs a musician to repeat a song or passage from the beginning, often abbreviation D. C. Da capo al fine means repeat from beginning to end. Da capo al segno means repeat until the point marked with a sign is reached.

DA converter – Digital-to-Analog converter. Also written D/A converter and D-A converter.

DAC – Digital-to-Analog converter.

DAD – Digital Audio Denmark.

DAE – (1) Digidesign Audio Engine. The DAE is the underlying code designed by Avid (formerly Digidesign) used to allow Pro Tools to communicate with computer hardware and software. Pro Tools is basically a user interface that tells the DAE (which runs in the background) what needs to be done. With PT 11, it was replaced with the AAE. (2) Digital Audio Extraction. See rip.

dailies – the raw, unedited footage shot each day during a film production, used to assess the progress of the film. Also called rushes.

daisy chain – (1) The connection of several devices in such a manner that the signal must pass through one device to reach a second device and through a second device to reach a third device and so on. (2) To connect several devices in such a manner.

damp – to suppress or reduce vibrations of a musical instrument to reduce the volume of sound. Also called to choke, especially with cymbals. Also sometimes used incorrectly as dampen, which means to make wet.

damped waves – (1) A wave in which the amplitude decreases with time. (2) An early method of radio transmission produced by spark-gap transmitters. By turning the transmitter on and off (on-off keying), information could be transmitted with damped electromagnetic waves using Morse code and were the first practical means of radio communication (now called Class B emissions). There is a general prohibition of using Class B damped waves, because they use a wide bandwidth and generate noise (electromagnetic interference) that interferes with other radio transmissions. See also continuous wave.

dampening – often used incorrectly for damping. Dampening is the act of making something moist.

damper pads – self-adhesive pads made from a soft, sticky, gel that can be applied to the surface of drums, cymbals, and other percussion instruments to reduce unwanted resonances and to produce a punchier sound. The most common brand is MoonGel® pads manufactured by RTOM. Also called gel pads, resonance pads, damping pads, and (incorrectly) dampening pads.

damping – (1) The suppression of vibrations using an electrical or mechanical device. (2) The quieting or silencing of the strings of an instrument after they have been played. Sometimes called choking. (3) The decreasing in amplitude of an electrical or mechanical wave due to friction and other forces. (4) The reduction of echoes and reverberations by using sound-absorbing material. Sometimes incorrectly called dampening.

damping factor – (1) In an audio system, the ratio of the rated impedance of a loudspeaker to the source impedance, using only the resistive portion of the impedance of both the speaker and amplifier. It is an indication of the ability of an amplifier to absorb voltage feedback from the speaker. When a signal going to the speaker stops, inertia causes the cone to continue to vibrate, which generates a voltage. The output circuit of the amplifier attempts to stop the vibrations by presenting a very low impedance load. (2) In a series of damped oscillations, the ratio of the amplitude of one oscillation to the next.

damping material – a substance that absorbs, reduces, or disperses sound waves in order to control reverberation. Sometimes incorrectly called dampening material.

damping pads – see damper pads.

damping ratio (ζ) – a measure of how rapidly a vibration decays. It is represented by the Greek letter zeta (ζ). ζ = 1/2Q, where Q = quality factor. A system is defined as overdamped when Q < ½, underdamped when Q > ½, and critical damped when Q = ½. The damping ratio is defined as ζ = damping/critical damping = c/c_c, where c is the damping coefficient and c_c is the critical damping coefficient.

dance music – see electronic dance music.

Dante – Digital Audio Network Through Ethernet. A combination of software, hardware, and network protocols to deliver uncompressed, multichannel, low-latency digital audio using Audio over Ethernet (AoE). It was developed in 2006 by Audinate as an improvement over CobraNet and EtherSound. See also Dante Virtual Soundcard.

Dante Virtual Soundcard (DVS) – software produced and licensed by Audinate as an interface between a computer and a Dante network. DVS uses the Ethernet port on most computers to connect with Dante-enabled audio devices on a network, without the need for snakes, converters, special cables, or external devices. It allows recording and playback of up to 64 channels using a DAW or other audio applications.

DAO – Disc-At-Once. See optical disc recording modes.

DAP – Digital Acoustics Processor

D'Appolito configuration – see midrange-tweeter-midrange configuration.

DAR – (1) Digital Audio Radio. (2)  Digital Audio Recorder.

dark – a descriptive term for a sound that is lacking in high frequencies. Also called dull. The opposite of bright.

darkness – the amount of low-frequency or lack of c content in an audio signal, which tends to make the sound appear farther away. The opposite of brightness.

DARS – (1) Digital Audio Reference Signal. A digital signal carrying timing or clock data, but no audio data (digital black), sometimes used to synchronize digital audio devices when word clocks are not practical. Standards for DARS are specified in AES11. (2) Digital Audio Radio Service. The official FCC term for digital radio services. Sometimes called DAR. See also Satellite Digital Audio Radio Service.

DASH – (1) Digital Audio Stationary Head. (2) Dynamic Adaptive Streaming over HTTP.

DAT – Digital Audio Tape. (1) The cassette containing magnetic tape used in a DAT recorder. Also called a Digital Compact Audio Cassette (DCAC). (2) Short for a DAT recorder. DAT should not be confused with digital audiotape.

data compression – the computer process in which a data file is reduced in size by eliminating redundant information, useless information, or data determined by various algorithms to be unnecessary. The file is returned to usable form through decompression. Data compression is sometimes divided into three levels: (a) Low bit rate (used in mobile and free streaming services), (b) Medium bit rate (used on desktop and mobile subscription services), and (c) High bit rate (used in desktop subscription services). Also called data compression, digital compression, data reduction, or data reduction.

data file – see file.

datapath – a collection of functional units in a computer, such as data processors, registers, and buses, that along with the control unit make up the central processing unit (CPU). Sometimes spelled data path.

datapath width – the size of the datapath in a computer in bits. The datapath width is a large factor in determining a computer's performance and is part of its architecture. Early computers had 8-bit datapath widths, and progressively have grown to 16, 32, and now 64 bits. Sometimes called bit version, bit architecture, digital data architecture, or bit computing.

data rate – see data transfer rate.

data reduction – see data compression.

data stream – (1) A sequence of digitally encoded signals used to transmit data. (2) The continuous flow of data from one location to another.

data transfer rate – the speed at which digital data is transferred between two devices or over a network, usually expressed in bits per second (bps). Sometimes called a data rate or bit rate.

DAT recorder – a digital audio recorder that uses a helical scanning process similar to a videocassette recorder to encode digital audio signal onto a magnetic tape cassette (DAT).

DAW – Digital Audio Workstation.

DAW automation – see automation.

dB – abbreviation for decibel.

dB(0.775V) – the official designation for the preferred informal abbreviation of dBu.

dB(1.0V) – the official designation for the preferred informal abbreviation of dBV.

dB(A) – an unofficial but often-used method for expressing loudness measurements using an A-weighting curve referenced to a loudness level of 40 phons. Sometimes shown as dbA.

dB(B) – an unofficial but often-used method for expressing loudness measurements using an B-weighting curve referenced to a loudness level of 70 phons. Sometimes shown as dbB.

dB(C) – an unofficial but often-used for method expressing loudness measurements using an C-weighting curve referenced to a loudness level of 100 phons. Sometimes shown as dbC.

dBf – a unit for the power ratio in decibels (dB) referenced to 1 femtowatt (10^-15 watts). dBf = 10 x log (P/P_f), where P is the power being measured and P_f is the reference value of 1 femtowatt.

dB(FS) – see 0 dBFS.

dBFS – see 0 dBFS.

dB Full Scale – the same as dB(FS) or dBFS. See 0 dBFS.

dB(fW) – the official designation for the preferred informal abbreviation of dBf.

dBi – Decibels-isotropic. See antenna gain.

dBLU – a measure of the loudness of an audio signal in decibels (dB), referenced to digital full scale, as used for loudness measurements according to ITU BS.1770. It is essentially the same as LUFS or LKFS, but is preferred by some authorities over those terms.

dBm – a unit for the power ratio in decibels (dB) referenced to one milliwatt (mW) (¹⁄1000 watt) at an impedance of 600 ohms. dBm = 10 x log (P/P_1mw), where P is the power being measured and P_1mw is the reference value of 1 milliwatt. Sometimes designated dBmW. The official designation is dB(mw).

dB meter – see sound level meter.

dB(mW) – the official designation for the preferred informal abbreviation of dBm.

dBr – a unit for a ratio to an arbitrary reference level that must be specified. dBr = 10 x log (P/P_r), where P is a power being measured and P_r is the reference power. Officially indicated as dB(relative).

dB(relative) – the official designation for the preferred informal abbreviation of dBr.

DBS – Direct-Broadcast Satellite.

dB-SIL – see sound intensity level.

dB-SPL – the sound pressure level measured in decibels (dB) above the standard reference level for no sound. The commonly used zero reference point for sound pressure level in air is 20 μPa (RMS) at 1000 Hz—usually considered the threshold of human hearing (at 1 kHz). dB(SPL)) = 20 x log (P/P₀), where P is the sound pressure being measured and P₀ is the 0 reference point. Sometimes shown as dBSPL and the official designation of dB(SPL). See also 0 dB(SPL).

dB-SWL – see sound power level.

dBTP – a measure of the true peak level of a signal in decibels (dB), referenced to digital full scale, used in loudness measurements under ITU BS.1770. It is the maximum value of a reconstructed audio signal taking into account any inter-sample peaks.

dBu – a unit for the audio voltage in decibels (dB) referenced to 0.775 volts RMS (Vrms). This unit is derived from the power standard of 0 dBm being equals to 1 mW into 600 ohms. A level of +4 dBu is the standard professional reference level equal to 1.228 volts RMS (Vrms) and is equal to 0 VU for a 1000 Hz tone for most professional equipment. dBu = 20 x log (V/V_0.775V), where V is the voltage being measured and V_0.775V is the reference voltage. At one time, this unit was designated dBv, but was changed to dBu to avoid confusion with dBV. The dBu unit is often used in professional audio, whereas the dBV is frequently used in consumer audio specifications. The official designation is dB(0.775V).

dBV – a unit for the audio voltage in decibels (dB) referenced to 1.0 volt RMS (VRMS) at any impedance. dBV = 20 x log (V), where V is the voltage being measured. The dBV unit is often used in consumer audio, whereas the dBu is frequently used in professional audio specifications. The official designation is dB(1.0V).

dBW – a unit for the power ratio in decibels (dB) referenced to one watt (W). dBW = 10 x log (P), where P is the power being measured. The official designation is dB(W).

dB(W) – the official designation for the preferred informal abbreviation of dBW.

dbx – a series of noise reduction systems developed by dbx, Inc. The most common versions are are dbx Type I and dbx Type II used for analog tape recording. These methods are different from Dolby noise reduction systems in that they use dynamic range compression during recording and expansion during playback to lower noise. There was also a dbx-TV that was part of the MTS system used for stereo sound in the US before digital television took over. The dbx noise reduction systems are rarely used today.

dbx 160 Compressor – a compressor designed by David Blackmer and introduced by dbx in 1976. Using RMS level-detection and feed forward circuits, it provided a much smoother gain reduction and allowed infinite compression without excessive distortion or oscillation. It was one of the first compressors with a soft knee.

dbx, Inc. – a US manufacturer of professional audio and recording equipment headquartered in Sandy, Utah. Founded in 1971, its name came from early products based on the concept of “decibel expansion.” It is probably best known not only for building dynamics processors, but for the dbx noise reduction system which became synonymous with its name. In 1979, dbx was bought by BSR. In 1989, Sanju Chiba of ELPJ acquired the dbx division of BSR, while the professional products division of dbx was sold off separately to AKG. AKG was bought by Harman International in 1994. The OEM business was sold to THAT Corporation founded by members of dbx's engineering group.

dB(Z) – see Z-weighting.

dc – Direct Current. Although it is frequently written as DC, the official abbreviation uses lower case.

DC – Digital Cinema.

D.C. – Da Capo. A musical term meaning “Play from the beginning.”

DCA – Digitally-Controlled Amplifier.

DCA, Inc. – a company located in Cushing, Oklahoma, that provides products for mastering and verifying optical discs, as well as producing hard disc drives, high-capacity optical storage devices, and gaming systems.

DCAC – Digital Compact Audio Cassette. See DAT.

dc bias – see tape bias.

DCC – Digital Compact Cassette. The digital version of the standard analog cassette tape system developed by Philips. It could play and record digital cassettes as well as analog cassettes. The system never really caught on commercially.

dc coupling – the transfer of electrical energy by means of physical contact using a conductor, as opposed to to inductive coupling and capacitive coupling. Because capacitors tend to attenuate certain frequencies, a circuit coupled without capacitors will tend to pass the complete audio spectrum with no loss. Also called direct coupling or conductive coupling.

DCE – Data Communications Equipment. The part of the RS-232 standard that specifies the equipment needed to establish, maintain, and terminate a connection, and the signal conversion and coding for communication between the data terminal equipment and the data circuit.

dc erasure – see erase.

DCF – Digitally-Controlled Filter.

DCI – Digital Cinema Initiatives.

dc noise – see tape noise.

DCO – Digitally-Controlled Oscillator.

dc offset – the amount of voltage above or below the zero point when no signal is present. This offset is an imbalance occasionally introduced by A/D converters. When present in an audio signal, dc offset reduces headroom and can cause premature clipping. It also can cause low-frequency distortion, which may be inaudible in the original signal, but may become audible when converted to a lossy format, such as MP3. It can and should be removed with software designed for that purpose. See also dc bias as discussed under tape bias.

DCP – Digital Cinema Package.

D connector – see D-subminiature connector.

dc tape bias – see tape bias.

D curve – see D-weighting.

DD – Dolby Digital.

DD+ – Dolby Digital Plus.

DDEX – Digital Data Exchange, LLC. An organization founded in 2006 by a consortium of media companies, music licensing organizations, and digital service providers to create digital supply chain standards (originally for digital music, but later expanded to include all forms of digital media). DDEX established the standard format for including information in XML messages and the method of exchanging these messages between interested parties. Some of standards developed by DDEX include (a) ERN (electronic release notification), which provides commercial information about releases, (b) DSR (digital sales report), a standard method of reporting sales figures to record labels and PROs, and (c) RIN (recording industry notification), a standard for metadata that provides recording credits, such as the names of musicians, producers, engineers, studios, and other parties. All names include the ISNI (international standard name identifier).

DDL – Digital Delay Line. See delay line.

DDP – Disc Description Protocol.

DDR – (1) Direct-to-Disc Recording or (2) Direct-to-Disk Recording.

DDS – Direct Digital Synthesizer.

deactivate – see disable.

dead – having very little or no reverberation. The opposite of live.

dead note – see ghost note.

dead room – a room with heavy sound-absorbing materials having essentially no reverberation.

dead spot – (1) In acoustics, a location where out of phase sound waves cause cancellation resulting in substantially reduced volume. (2) With wireless transmission, a location where there is little or no reception. (3) With stringed instruments, a particular note on the neck of the instrument that does not resonate or sustain well.

dead wax – slang for run-out groove area.

DEC – Digital Equipment Corporation.

decade – (1) The interval between two values where the second value is ten times the first, often plotted on a logarithmic graph. (2) A frequency ratio or interval of 10:1, as opposed to an octave, which is a 2:1 ratio. [The decade interval has no musical significance, but is used for convenience with logarithmic units, such as decibels.] (3) Sometimes the rolloff of a filter or equalizer is expressed in dB/decade, rather than in dB/octave. Because there are 3.3219 octaves in one decade, a rolloff of 6 dB/octave equals 20 dB/decade, 12 dB/octave equals 40 dB/decade, etc.

decay – (1) The reduction in a signal from its original level to a sustained level. The second of the four segments of an ADSR envelope. (2) The fading out of a reverberation of a sound.

decay curve – a plot (energy-time curve) of the reverberation tail that occurs following a sound. It can be obtained by backward integration (integration in reverse) of an impulse response measurement, a technique developed by M. R. Schroeder of Bell Labs, and sometimes called the Schroeder method. Such a curve is called a Schroeder curve. See also reverberation time.

decay rate – how fast an echo or reverberation diminishes after the sound has stopped, measured in decibels per second. Depending on the sound source and the space, the decay rate may be linear (decreasing at a constant number of dB/sec), or it may begin to decay slowly or rapidly and then change. The decay rate depends on the amount of sound absorption in a room, the room geometry, and the frequency of the sound.

decay time – (1) The time (in seconds) it takes for a reverberation to be reduced in level by 60 db. Also called reverberation time, abbreviated as RT, RT60, RT-60, or RT60. (2) The time (in seconds) it takes for the amplitude of a signal to decay from one specified value to another specified value, typically from 90% of the maximum amplitude down to 10%. Also called fall time. See also rise time.

Decca Records – a record label established in the UK in 1929. The US division of the label was established in 1934. However, during World War II, the link between the two companies was severed for several decades. Both labels are now part of the Universal Music Group which is owned by Vivendi, a media conglomerate headquartered in France.

Decca tree – a stereo microphone technique developed by Roy Wallace and Arthur Haddy at Decca Studios in London in the 1950s, most commonly used for orchestral recording. Originally it used three cardioid microphones, but later switched to omni microphones (Neumann M50s). The mics are arranged in an upside-down “T” pattern. Two microphoness are placed left and right approximately 2 m (6 ft) apart with the third placed in the center about 1 m (3 ft) in front, approximately 2.5 - 3 m (8 - 10 ft) up. The side mics are panned hard left and right while the third mic is mixed dead center. This technique produces a strong stereo image. It is sometimes called A-B-C stereo, A/B/C stereo, or ABC stereo. See table comparing various stereo microphone techniques. See also wall of sound, definition #2.

deci- (d) – the SI prefix for a factor of one tenth (10^‑1).

decibel (dB) – ¹⁄10 of a bel, a logarithmic unit used to express the ratio between two values of power. It has come to be used for expressing the ratio of other values as well. Because a decibel is a logarithmic expression of relative power levels, a change in sound volume expressed in decibels approximates the change heard by the human ear. (See dB(SPL).) In order to express the level of a signal in dB, you need to know the reference level of the power to which it refers. The decibel abbreviation (dB) usually adds a suffix to indicates which reference level is used. For example, dBm indicates a reference level of one milliwatt. To calculate the dB value of a power, the formula is dBm = 10 log (P/P_1mw), where P is the power being measured and P_1mw is the reference value. When used with voltage, the formula becomes dBV_R = 10 x log (V/V_R)² or dBV_R = 20 x log (V/V_R), where V is voltage being measured and V_R is the reference voltage, because power is proportional to the square of the voltage. There are a variety of units to measure sound, such as dB(A), dB(C), and dB(SPL). Units for measuring voltage include dBu and dBV. Units for measuring power include dBm and dBf. For other decibel units, look under dB above.

decibel meter – see sound level meter.

decimal – (1) A system of numerical notation that uses 10 as a base. (2) Pertaining to the decimal system or decimal notation.

decimation – the process of reducing the sample rate, typically by lowpass-filtering and then dropping some samples from a stream of oversampled digital audio data. Decimation is usually used to lower the data density to a point where it be easily handled.

decimation filter – a digital filter that uses decimation to reduce the processing required. The output sample rate must be above the Nyquist frequency to avoid aliasing problems.

decimation ratio (DR) – the ratio of the starting sampling rate to the final sampling rate in the process of decimation. DR = fS/fD where fS is the starting sampling rate and fD is the resulting rate.

deck – a slang term for a tape player, but sometimes applied to turntables or CD players.

deck plate – the heavy metal plate on a tape machine upon which the headstack, guide, rollers, and other transport components are attached.

de-clipping – an algorithm that searches through an audio file to find where clipping occurs (the signal exceeded 0 dBFS) and then attempts to reconstruct the signal. Most such processes are only partially successful and are much better on lightly clipped material.

de-clicking – an algorithm that searches through an audio file to find sharp transients, such as those caused by crackly guitar cables, clicky synthesizers, mouth noises, or vinyl record clicks and pops, and then attempts to remove or reduce the transients. Such processors can sometimes introduce artifacts if overdone.

decode – (1) To restore a signal to its original state by reprocessing the signal in a manner complementary to the way it was encoded, such as a noise reduction system re-expanding the signal during playback. (2) To convert digital data back into an analog signal, in other words, to make a digital-to-analog conversion. (3) To extract information that has been previously imparted onto an audio signal, such as spatial information. The opposite of encode.

decoded tape – a recording tape that has been expanded after having been encoded by a noise reduction system, such as Dolby, returning it back to its original dynamic range.

decoder – (1) A device or algorithm that converts a digital signal into an analog signal. In other words, a digital-to-analog converter. Sometimes called a digital decoder. (2) To restore an audio signal back to the original from the signal that has had a noise reduction process applied. (3) A device or box attached to a television set used to unscramble encoded signals, such as cable-television programs or closed captioning, so they can be displayed on the screen.

decompress – to return a data file that has been previously reduced in size using data compression to a usable form. Not to be confused with uncompressed which refers to a file that has never been compressed.

decompression – the process in which a data file that has been previously reduced in size using data compression is returned to a usable form.

deconvolution – a mathematical process for separating two signals that have been convolved (mathematically combined using convolution).

decorrelation – the process of very subtlety changing the phase and time relationship of two surround channels so they do not sound exactly identical, in order to create a more spacious sound. Some early surround sound systems had only one surround channel with both speakers receiving the exact same signal, which can cause the sound to be “in your head” or cause the surround sound to collapse to the speaker nearest you. The term was originally applied to a technique used in home THX systems to create a more diffuse, full surround sound by transforming identical audio signals in surround channels into different but similar-sounding waveforms. Dolby Digital's two discrete surround channels did not make decorrelation obsolete, since many sounds still are sent equally to both surround channels. Decorrelation was updated to Adaptive Decorrelation, which adapts to the incoming signal, so only content that is identical in both channels is decorrelated, while the rest of the sounds remain unchanged. Adaptive Decorrelation™ is a trademark of THX, Ltd. Sometimes shown as de-correlation.

decoupler – see isolator.

decoupling – see mechanical decoupling.

decrescendo – (1) A gradual decrease in the loudness of a section of music. (2) A musical symbol resembling a long “V” laying on its side and pointing to the right that indicates a decrease in loudness. The opposite of crescendo. Also called diminuendo.

decrement – (1) To decrease the settings on a device, especially by a small amount. (2) A decrease in the settings of a parameter. Opposite of increment. Compare with cut definitions #1 and #2.

DECT – Digital Enhanced Cordless Telecommunications.

deejay – see disc jockey.

deejay mixer – see DJ mixer.

de-emphasis – see emphasis.

deep bass – one of four subdivisions into which bass is sometimes divided, covering the range of 20 Hz to 40 Hz. The other three subdivisions are low bass (40 Hz to 80 Hz), mid bass (80 Hz to 160 Hz), and upper bass (160 to 350 Hz), although these ranges vary from source to source. See also audio spectrum.

de-esser – a device, plug-in, or circuit that reduces excessive sibilance, the sound of “s,” “sh,” “c,” “ch,” “j,” and “z.” Sometimes spelled deesser. Also called a desibilizer. See also split-band de-esser.

definition – the quality of a sound that allows it to be differentiated from other sounds.

DEG – Digital Entertainment Group. A group of movie studios, consumer electronics retailers and manufacturers, and technology providers formed to promote new forms of digital home entertainment. It was formed in 1997 as the DVD Video Group. It was later renamed DVD Entertainment Group, to include DVD-Audio and DVD-ROM. In 2003, it changed its name to the Digital Entertainment Group, to include newer formats including HDTV, 3D TV, 4K Ultra HD TV, Blu-ray Disc, 4K Ultra HD Blu-ray Disc, and Digital HD downloads. degausser – see demagnetizer.

degree – see scale degre.

delay – (1) The time it takes for a hardware or software function to accomplish a task, which can lead to latency. (2)  A delay effect. (3) A delay time.

delay compensation – a feature in a DAW or software that automatically or manually corrects for timing delays caused by signal processors, plug-ins, hardware, or other processes that contributes to latency. Also called latency compensation or plug-in delay compensation (PDC). See also automatic delay compensation (ADC).

delay effect – a signal processor that temporarily stores a sound and then play back after period of time. Typical controls include delay time, feedback (the number of times a signal is repeated to create the sound of a repeating, decaying echo), wet/dry mix, and modulation (which varies the delay time up or down by speed [how fast] and depth [how much]).

delay line – a device used to delay an audio signal for a delay or reverberation effect. It can be either an analog delay line (ADL), which consists of electronic components that create a time difference, or a digital delay line (DDL), which creates a time difference using an algorithm.

delay time – the time interval between a sound and the repeat of that sound, used to create a delay or echo effect.

delicate – a descriptive term for smooth sounds in the very high frequencies—in the 15 kHz to 20 kHz range.

delta modulation (DM) – a technique for analog-to-digital and digital-to-analog conversion used primarly for the transmission of voice data where quality is not important. Delta modulation determines the change (the delta) in the signal, not its absolute value. Using oversampling, a 1-bit sample is taken. The sample is 1 if the signal is rising, zero if decreasing, and remains at the same 0 or 1 state of the previous sample if flat. Delta modulation is a form of differential pulse-code modulation (DPCM) where the differences between successive samples are encoded into data streams using several bits, whereas delta modulation only uses one bit. Delta-sigma modulation is an improvement over delta modulation that produces a higher quality signal. Sometimes written as Δ-modulation.

delta-sigma modulation – a method for converting analog signals into digital signals using an analog-to-digital converter (ADC). It is also used to convert higher-resolution digital signals into lower-resolution digital signals. With conventional ADC, an analog signal is sampled one sample after another at a given sampling rate, a process that introduces quantization error noise. With delta-sigma modulation the first step is delta modulation, which determines the change (the delta) in the signal, not its absolute value. Using oversampling (64 times the CD rate of 44.1 Hz or 2.8224 mHz) a 1-bit sample is taken. The sample is 1 if the signal is rising, zero if decreasing, and remains at the same 0 or 1 state of the previous sample if flat. This results in a stream of analog-like pulses, as opposed to a stream of digits as with PCM. This signal is decimated (downsized) before it is summed (sigma) to the input signal. This technique is finding increased use due to its lower cost and simpler circuit design. Although delta-sigma signals are inherently less data-intensive than PCM, they cannot be manipulated mathematically as easily, which makes them somewhat more difficult to process. Sometimes called sigma-delta and abbreviated as ΔΣ or ΣΔ. See also Direct Stream Digital (DSD).

demagnetizer – an electromagnetic device used to remove residual magnetism from items in the tape path on a tape machine (such as, tape heads and tape guides). Also called a head demagnetizer or degausser.

demo – (1) A recording made to exhibit the capabilities of an artist, usually to obtain a contract with a label or to obtain a booking. (2) A recording made to present a new song, usually recorded by or for the songwriter for submitting to an artist or producer in hopes of inducing the artist to record it. (3) A recording made to introduce a new song to other members of a band or group to aid in rehearsing the song prior to performing it live or in a studio. Short for demonstration.

demodulation – the process of extracting a signal from a carrier wave upon which the signal was originally imposed during modulation. For example, the process of extracting music or voice from an FM broadcast signal.

dempo – short for down tempo. To decrease the tempo of a song. Opposite of umpo.

demultiplex – to split a file containing both audio and video data into separate files, each containing video or audio only. The demuxing process does not degrade the video nor audio quality. Called demux for short.

demux – short for demultiplex.

denoiser – software that removes pops, clicks, hum, hiss, and other noises from an audio file. See also audio restoration.

Denon – Kabushiki Kaisha Denon. A Japanese electronics company involved the design and manufacture of professional audio and consumer audio equipment. It was one of the early pioneers in the development of digital audio technology. The company was founded in 1910 as Nippon Denki Onkyo Kabushikigaisha, a division of Nippon Chikuonki Shokai (Japan Recorders Corporation), and manufactured single-sided records and gramophone discs. The was shortened Denon. It merged with Japan-US Recorders Manufacturing in 1912 and then in 1928 it became Japan Columbia Recorders. In 1946 the company was renamed Nippon Columbia. In 2001 Denon was spun off as a separate company. In 2002 it merged with Marantz to form D&M Holdings. It is now part of inMusic Brands.

density – (1) A parameter found on many reverb units or plug-ins that determines the space between reflections. Higher settings place reflections closer together. As a rule, higher densities work better for percussive sounds, while lower densities work better for vocals and sustained sounds. Compare with diffusion. (2) The mass per unit volume of a material, expressed as kilogram per cubic meter (kg/m3). Density (ρ) is defined by ρ = m/V where ρ is the density, m is the mass, and V is the volume. Density is an important factor in choosing materials for sound absorption.

depth – (1) The perception of nearness and farness in an audio mix. The human ear determines depth by the ratio of direct and reverberant sounds for a given instrument or voice with more reverberation being perceived as farther away. Also called depth perception or front-to-back imaging. (2) A descriptive term for a full-bodied sound, especially of an instrument. See body. (3) A parameter in a digital delay or flanger that adjusts the length of delay. (4) Short for bit depth.

depth perception – see depth, definition #1.

de-reverb – see dereverberation.

dereverberation – (1) An algorthm for removing reverberation from an audio signal. Removing reverberation is a complex process, and although some progress has been made in this regard, most efforts have met with only modest success. Also called de-reverb or un-reverb. (2) See room equalization.

descant – in music, a melody or counterpoint accompanying the main melody of a song or hymn, often sung in a higher pitch or by soprano voices. As an adjective it means treble or soprano (mainly British).

designation strip – a piece of tape or a strip of paper taped along the bottom edge of a mixer or console to indicate the instrument that each fader controls.

Deramic Sound System (DSS) – a recording technique developed in the 1960s by DERAM intended to produce orchestral recordings that had a more natural, spacious stereo spread. Among other things, instruments were spaced further apart and special overdub techniques were employed, along with the use of cross-delayed echo. DERAM was a subsidiary label of UK Decca, which was a separate company from US Decca, which at the time was owned by MCA. Sometimes called the Decca Panoramic Sound.

derivative work – work (such as a piece of music, a works of art, or a work of literature) that is based on another pre-existing work. Since a copyrighted work is protected from any and all derivatives of that work, permission from the original copyright holder must be obtained before the derivative work may be copyrighted.

DES – Dolby-Encoded Stereo.

desibilizer – see de-esser.

desk – the British term for a mixing console.

destructive editing – editing a digital signal in such a way that it cannot be undone. Non-destructive editing allows you to make changes without destroying the original content.

destructive interference – see phase cancellation.

detailed – a descriptive term for sound in which it is easy to discern tiny features, characterized by sharp transient response and good high-frequency response. Also called articulate.

detector – see level-sensing circuit.

detector circuit – see side chain.

detent – a stop, catch, or notch in a rotating control, such as in a variable resistor to denote various steps or in the midpoint of a pan control to designate the default setting.

detune – to tune slightly off the correct tuning, usually slightly flat, in order to create certain special effects, such as a fuller sound when doubletracking.

detuner – an effect that detunes a note by a small amount and then combines it with the original note, and sometimes adds a delay of up to 60 ms. The effect is similar to chorus, but without the swirling effect. It is useful for thickening up guitar notes or enhancing chords.

deviation – see frequency deviation.

device driver – a computer program that operates, controls, and communicates with a specific device that is attached to a computer. Every device, such as a printer, disk drive, keyboard, or audio interface, must have a driver. Some drivers come with the operating system (OS), but for other devices, it is necessay to install a new driver when connecting a new device to the computer. In Window systems, drivers typically are files with a .sys or .drv extension. Often called simply a driver.

device under test (DUT) – a product or device being tested for calibration or to make sure it meets design specifications. Such testing can occur during manufacture or after being placed into service. Also known as equipment under test (EUT) and unit under test (UUT).

DFA – Does F**k All (does nothing). A euphemism for a knob, slider, or control that is bypassed or is not connected (or a pretended adjustment) used when a client is perceived to be making endless or unreasonable adjustments. After using the DFA knob (which does nothing), the engineer then asks the client if it sounds better, and often receives a positive reply.

DFF – DSD File Format. A DSD audio file format using the .dff extension, which contains no metadata. Compare with DSF, which does contain metadata.

D filter – see D-weighting.

DFTC – Drop-Frame Time Code.

DI – (1) Direct Input or Direct Injection. (2) Directivity Index .

dialnorm – see dialog normalization.

dialog – the lines spoken by characters in a stage, movie, or television performance. Narration is usually included as a part of dialog. British spelling dialogue.

dialog normalization (DN) – the metadata parameter within Dolby Digital (AC-3) for control of playback gain. DN is an integer value in the range of 1 to 31 that corresponds to a playback gain of -30 to 0 dB (unity gain) respectively. Lower values provide more headroom and are appropriate for material with greater dynamic range, such as action films. The DN value should be determined by measuring the average dialog level using A-weighted audio levels in all channels. In this way, the dialog levels will be normalized—thus the name dialog normalization. [Note: DN does not comply with the loudness standard ATSC A/85.] Called dialnorm for short.

dialog replacement – see automatic dialog replacement.

dialog track – the portion of a soundtrack that contains the dialog. The “D” part of DME.

diameter loss – the loss in fidelity as the stylus moves from the outer part of a vinyl record toward the center. This phenomenon occurs because the record operates at a constant angular velocity (CAV) meaning the linear velocity decreases as the diameter decreases, resulting in a lower resoluton and loss in high frequency response. A vinyl mastering engineer can compensate with adjustments in equalization as the the groove proceeds toward the center, but this can sometimes increase distortion.

diapason normal – diapason can mean (1) the entire range of musical tones, (2) a standard pitch, or (3) a tuning fork. Diapason normal was a standized tuning proposed by the French government in 1859. See A440.

diaphragm – (1) The thin membrane in a microphone that vibrates in response to a sound wave, such as the front plate of the capacitor in a condenser microphone, the thin aluminum ribbon in a ribbon microphone, or the thin sheet of metal attached to the moving coil in a moving coil microphone. (2) Another name for a speaker cone. (3) Any surface that vibrates in response to sound or that is vibrated to emit sound, including wall and floors.

diaphragmatic absorber – see panel absorber.

diaphragm electret condenser microphone – see electret condenser microphone.

diatonic accordion – see accordion.

diatonic comma – see syntonic comma.

diatonic chord – a chord using only notes from the same diatonic scale. If a chord includes at least one note that does not not belong to that diatonic scale, it is a chromatic chord. Also called diatonic harmony.

diatonic harmony – see diatonic chord.

diatonic note – one or more notes from the same diatonic scale.

diatonic scale – an eight-note musical scale composed of seven pitches and a repeated octave. The diatonic scale uses five tones (whole steps) and two semitones (half steps) (in the equal tempered tuning system). Diatonic scales can be in either a major or minor key, depending on the sequence of intervals in terms of tones and semitones. A major scale has the following sequence: tone-tone-semitone-tone-tone-tone-semitone. A natural minor scale has this sequence: tone-semitone-tone-tone-semitone-tone-tone. A harmonic minor scale follows this sequence: tone-semitone-tone-tone-semitone-1½ tones-semitone. The melodic minor scale is like the natural minor scale except the sixth and seventh notes are raised a semitone when ascending and remains the same when descending. See also mode.

Diatonic Scales
Degree	Note Name	Alternate Name	Major Key Chord	Minor Key Chord
1st	Tonic	Keynote	I	i
2nd	Supertonic		ii	II
3rd	Mediant		iii	III
4th	Subdominant		IV	iv
5th	Dominant		V	v
6th	Submediant	Superdominant	VI	vi
7th	Leading Tone	Leading Note	vii°	VII
8th	Tonic	Octave	I	i

DI box – see direct input box.

dichotic – having different sounds present in each ear, the opposite of diotic.

dichotic listening – listening to different audio signals simultaneously in each ear.

diegesis – (1) The telling of a story in which the experiences of the characters are revealed by a narrator who lays out the plot and sometimes comments on the conversations and thoughts of the characters. (2) The world in which such narrated events and other actions take place. See also mimesis.

diegetic music – see source music.

diegetic sound – a sound that is present or implied as being present in a film, video, or video game, such as character voices, sound effects, or music that is being played on the screen. Diegetic sound is any sound presented as originating within the world being depicted. It is also called actual sound. It is the opposite of non-diegetic sound.

dielectric – a substance that is a poor conductor of electricity, but that can be polarized by an applied electric field to create an electrostatic field, which can store energy. This property is useful in constructing capacitors. Also called a dielectric material.

dielectric material – see dielectric.

DIF – Digital InterFace. See digital input.

difference-in-time stereo – see time-difference stereo.

difference tone – a tone equal to the difference in frequency of two other tones sounded at the same time. For example, two tones of 2,000 Hz and 2,500 Hz will generate a difference tone of 500 Hz, which is also called the beat frequency. A difference tone will occur if the two tones are not in the same harmonic series and have a difference greater than 20 Hz. A frequency difference of less than that is perceived as beating. Also called a subjective tone or resultant tone.

differential amplifier – an amplifier that amplifies the difference between two voltages rather than the voltages themselves. With one lead being positive and the other equal but negative, it multiplies the difference by a constant amount. Differential amplifiers are used in many applications, such as, microphones, analog-to-digital converters, and automatic gain controls.

differential microphone – a double-button carbon microphone. See carbon microphone.

differential mode – a signal that has a positive component and an equal but negative component that are transferred along two wires. This is the opposite of common mode. Also called normal mode.

differential signal – a signal that uses two wires that are the inverse of one other (when one is positive, the other is negative and of equal magnitude) with the signal being the difference between the two. Any common-mode voltage is ignored. This arrangement minimizes electrical interference as external noise will affect both wires equally. This is the type of signal used for most microphone inputs and uses a balanced line.

diffraction – (1) The bending of sound waves around obstacles and the spreading out of sound waves passing through openings, analogous to light diffraction. Diffraction is frequency-dependent. When the wavelength is short compared to the size of the obstacle, both reflection and diffraction occurs, but when the wavelength is long compared to the obstacle, more bending of sound waves occurs with very little reflection. See also refraction. (2) See edge diffraction.

diffraction grating – an optical device consisting of extremely small, parallel lines that break light down into its component colors. This concept has been used to desgn a sound diffuser, called a reflection phase grating (RPG).

diffraction loss – see edge diffraction.

diffuse – (1) Widely scattered or spread out. Not concentrated. (2) A descriptive term for a sound without directionality, seeming to come from no particular direction. The opposite of focused. (3) To scatter or evenly distribute sound energy within a space.

diffuse-field microphone – see microphone response types.

diffuser – a material or device that scatters sound or evenly distributes sound within a space. There are several types of diffusers: quadratic-residue diffuser (Schroeder diffuser), polycylindrical diffuser, primitive-root diffuser, hemispherical diffuser, and optimized diffuser. One advantage of all diffusers is that below the diffusion cut-off point, they still cause some reduction of low frequencies (bass trapping). An overall balance can often be obtained by using diffusion in combination with absorption. Also spelled diffusor. See also acoustic treatment.

diffuse sound field – a space with many reflecting surfaces and little absorption. A space having good diffusion and a uniform distribution of sound energy. Some examples are gymnasia, swimming pools, and interior spaces with hard walls made from concrete, marble, or glass.

diffusion – (1) The irregular reflection, refraction, and diffraction of sound in many directions. Also called scattering or acoustic scattering. (2) A parameter found on many reverb units or plug-ins that determines how diffuse the reflections are. A low setting produces reflections that are distinct echoes while higher settings produce diffuse, smeared, and indistinct sounds. In genersl, higher diffusion works better with percussive sounds, while lower diffusion works better for vocals and sustained sounds. Sometimes confused with density, a parameter that controls the number or rate of reflections.

diffusor – see diffuser.

DiGiCo Limited – an audio company headquartered in Chessington, Surrey, UK, that manufactures digital mixing consoles, especially for live audio mixing applications. DiGiCo was formed in 1996. It was purchased in 2011 by the investment company Livingbridge. It merged with Allen & Heath and Calrec in 2014 and became part of Audiotonix.

Digidesign – the digital audio technology company that designed Pro Tools. It merged with Avid in 1995, but Avid continued to use the Digidesign name until 2010. Digidesign was founded in 1983 by Evan Brooks and Peter Gotcher to develop and market digital drum sound libraries under the name Digidrums. In 1984, they introduced an sound editor called Sound Designer. In 1989, they introduced Sound Tools, a two-track digital recording and editing program. Sound Tools evolved into Pro Tools 1.0 in 1991. Pro Tools began as a Mac-based multitrack digital audio recording and editing system with DSP and onscreen mixing, but it later added the Windows platform.

Digidrums – see Digidesign.

DigiLink cable – a proprietary cable used by Digidesign (now Avid) for connecting Pro Tools HD I/O peripherals to HD Cores, HD process cards, or other peripherals.

digital – (1) A number or value represented as binary digits that can be read by a computer and converted back into data, as opposed to analog. (2) Indicating a readout, such as time or voltage, by means of displayed digits rather than hands or a pointer. (3) Using a computer or computer program to modify or improve data or a signal, as opposed to using analog methods, such as circuits.

Digital 8 (D8) – an 8-mm video format for digital video camcorders developed by Sony introduced in 1999. The Digital 8 format uses the same videocassettes as the analog Hi 8 camcorders, but the signal is encoded digitally using the DV codec.

digital acoustics processor (DAP) – a consumer audio device that attempts to simulate the acoustics of various halls and auditoriums by adding time delays and synthetic reverberation to audio signals.

digital audio – audio signals represented as binary digits which can be read by a computer and converted back into sound.

digital audio broadcasting (DAB) – see DAB and DAB+.

digital audio coding – (1) The process of converting an audio signal into a particular form that can be read by a computer or that can be transmitted. (2) The process of data compressing an audio file into a smaller size. (3) The process of adding additional information onto an audio signal, such as spatial information. Also called digital audio encoding.

digital audio converter – see digital-to-analog converter.

Digital Audio Denmark (DAD) – a wholly-owned business unit and brand of NTP Technology AS, that builds high-end analog-digital converters for the audio recording industry. It is headquartered in Gentofte, Denmark.

digital audio encoding – see digital audio coding.

digital audio file – see audio file.

digital audio interface – see audio interface.

digital audio player – a small portable consumer electronic device that stores and plays digital audio files, such as MP3, AAC, and WMA. Sometimes called an MP3 player, although ditial audio player is more generic. Also called a digital music player.. See also digital media player and iPod.

digital audio processing – see digital signal processing.

digital audio radio (DAR) – the name applied by EIA for digital radio broadcasting. See DAB, DAB+, HD radio and DARS.

digital audio recorder (DAR) – see digital recorder.

Digital Audio Stationary Head (DASH) – a professional audio, reel-to-reel, digital audio tape format with a stationary head developed by Sony that was an early competitor to DAT, but never became a commercial success. In fact the term R-DAT was used originally to distinguish DAT as the rotating head version, but eventually the “R” was dropped. DASH was sometimes called S-DAT. See also ProDigi.

digital audiotape – magnetic recording tape used to record digital audio. It comes in several formats including reel-to-reel, cassettes, and DAT.

digital audio taperecorder – a device that uses magnetic tape to digitally record audio. There are many types of digital tape recorder using a variety of non-compatible formats. They use two fundamental methods: multiple tracks or high tape speeds. Multitrack systems are expensive, but reliable. High speed machines achieve speed by using a rotating head, similar to video recorders. Early models were simply modified VTRs. In fact, the reason for the unusual CD sample rate of 44.1 kHz is because you can easily record 3 samples in a video frame. At 490 lines and 30 frames per second, you can record 44,100 samples per second.

digital audio workstation (DAW) – a combination of audio recording and editing software and hardware used to record, playback, mix, edit, and store digital audio files. There a number of DAW software programs currently being used, which vary in price from free to several thousand dollars. A few of the more common ones are Ableton Live, Audacity, Audition, Cakewalk Sonar, Cubase, Digital Performer, GarageBand, FL Studio, Logic Pro, Mixbus, Nuendo, Pro Tools, REAPER, Record, Samplitude, Sequel, Sequoia, Studio One, and Universal Audio Luna. Although today DAWs are mostly computer-based, they were originally standalone hardware digitial audio workstations.

digital audio workstation (DAW) automation – see automation.

digital black – a digital signal that contains no audio or video content, only metadata such as subcodes and timing signals.

digital chorus – see chorus.

digital cinema (DC) – using digital technology to distribute and project motion pictures as opposed to using motion picture film. DC can be distributed on hard drives, over the internet, via dedicated satellite links, or on optical discs, usually in the form of a Digital Cinema Package (DCP). Digital movies are projected using a digital projector rather than a conventional film projector. Digital cinema differs from high-definition television and does not use high-definition video standards, aspect ratios, or frame rates.

Digital Cinema Initiatives, LLC (DCI) – a joint venture established in 2002 by many of the major motion picture studios to to establish and document specifications for an open architecture for digital cinema that provides a uniform and high level of performance, reliability, and quality in digital motion pictures.

digital cinema package (DCP) – the collection of digital files that are sent to movie theaters to deliver the audio, image, and data streams of digital cinema (DC) as speciified by the Digital Cinema Initiatives. These packages contain a number of very large files, that store digital audio and video streams and index files, which are data compressed to reduce the file size and usually encrypted to protect them from unauthorized use.

digital component video – see component video.

digital compression – the same as data compression.

digital compressor – an audio compressor plug-in that does not emulate a hardware compressor, but takes advantage of the precision and versatility of digital technology to offer capabilities not found in hardware units. Examples include look ahead compressors and low-level compressors. See also tube compressor, VCA compressor, FET compressor, optical compressor, variable-mu compressor, PWM compressor, low-level compressor, and multiband compressor.

digital computer – a type of computer that performs calculations, processes data, and carries out logical operations with quantities expressed as digits, usually in the binary number system. It is the most commonly used type of computer. Compare with analog computer.

digital content – content.

digital data architecture – see datapath width.

digital decoder – see decoder.

digital delivery – see digital distribution.

digital delay – a digital processor that samples incoming audio, stores it in RAM, and then plays it back after a specified time period. It may add additional effects such as regeneration and feedback to create the sounds of an echo. See also analog delay.

digital distribution – the delivery or distribution of digital media, such as audio, video, software, and video games, over the internet. Also called content delivery, digital delivery, online distribution, or electronic software distribution (ESD).

digital domain – the processing of images, sounds, video, and other data that has been converted into a digital format and manipulated within a computer, as opposed to the analog domain.

Digital Enhanced Cordless Telecommunications (DECT) – a digital communications standard, used primarily for cordless phone systems, but also used in industrial applications such as for remote controls. Originated in Europe, it has become the standard there as well as in most other countries, having replaced earlier cordless phone standards. In the US a slightly different frequency range is used, making it incompatible with systems in other countries. Also called Digital European Cordless Telecommunications.

digital equalizer – an algorithm that uses a series of digital filters to emulate the function of an analog equalizer.

Digital Equipment Corporation (DEC) – a computer company once headquartered in Maynard, Massachusetts, that manufactured and sold computers, software, and peripherals under the Digital trademark. In 1998 it was purchased by Compaq Computers, which subsequently merged with Hewlett-Packard in 2002, with some divisions of DEC being sold to Intel.

digital era – the portion of recorded music history from about 1982 to the present. This era began with the introduction of the compact disc in 1982. During this period, the transition from analog recording to digital recording took place. Prior to this era, all audio recording was analog only. Also called digital recording era or the digital revolution.

digital filter – an algorithm that makes calculations that reduce certain frequencies of a digital signal leaving the rest. It is designed to emulate an analog filter, which is an electronic circuit that performs a silimar operation on an analog signal. See also IIR filter and FIR filter.

digital full scale – see full scale.

digital input – a connection that accepts digital audio signals. There are a number of digital input formats both optical and wired, including AES3 (AES/EBU), S/PDIF, ADAT, MADI, TDIF and others.

digital instrument – (1) A musical instrument that can be played or controlled by means of digital inputs, such as MIDI signals. (2) A measuring device that has a digital display.

digital jitter – timing variations in the sampling clocks used in digital audio, occurring both during A/D conversion and D/A conversion. Jitter causes low level distortion or noise and a loss of high-end definition in the audio signal. Although a compact disc itself has no jitter, the digital data can contain the effects of jitter produced during the A/D process and jitter can be further introduced when the CD is decoded in the D/A conversion. Once jitter has been introduced into the digital data it cannot be removed. Also called jitter, word-clock jitter, clock jitter, or sample offset uncertainty. See also intersymbol interference.

digital keyboard – see electronic keyboard.

digitally-controlled amplifier (DCA) – an amplifier design used primarily in synthesizers where the gain is controlled by a digital signal.

digitally-controlled filter (DCF) – an audio filter that is controlled by a digital signal, as opposed to one controlled by an analog signal.

digitally-controlled oscillator (DCO) – an oscillator used in synthesizers that is controlled by a digital signal, as opposed to one controlled by an digital signal, as opposed to one controlled by an analog signal.

digital media – any media, such as audio, video, and pictures, stored in a digital format. It is distinguished from the physical media (objects that can be touched and felt) on which it is stored, such as phonograph records, compact discs, and magnetic tapes.

digital media adapter – see digital media streamer.

digital media extender – see digital media streamer.

digital media hub – see digital media streamer.

digital media player (DMP) – see media player or digital media streamer.

digital media streamer – a consumer electronics device that can connect to a home network to stream digital media, such as music, pictures, or video, from personal computers, storage networks, or other networked media server, and even the internet. Also called digital media extender, digital media hub, digital media adapter, digital media player (not to be confused with a portable digital media player, or digital media receiver (not to be confused with an AV Receiver (AVR).

digital media receiver – see digital media streamer.

digital microphone – a microphone in which the analog signal is preamplified and converted to a digital signal using an analog-to-digital converter (ADC) within the body of the microphone. Digital microphones have lower noise and are less susceptible to electromagnetic interference than an equivalent analog microphone. See also USB microphone.

digital mixer – an electronic device (mixing board or console) used to combine, route, and change the dynamics of digital audio signals. Compared to analog mixers, digital mixers usually offer additional features, such as automation, presets, digital effects, and digital I/O. In some cases, digital mixers can function as a digital audio interface that can be used with a computer. Sometimes called a digital mixing console.

digital mixing console – see digital mixer.

digital multimedia broadcasting (DMB) – a digital radio transmission technology developed in South Korea for sending multimedia such as television, radio, and data to mobile phones, tablets, laptops, and GPS navigation systems. Although DMB was developed in South Korea, the underlying technology was developed by Dr. Gert Siegle and Dr. Hamed Amor at Robert Bosch GmbH in Germany. DMB is a competing technology with DVB-H. There are several classifications of DMB: satellite DMB (S-DMB), terrestrial DMB (T-DMB), and Smart DMB (which allows VOD service for smart phones). Also known as mobile TV.

digital multiplex – see DMX.

digital music – music in the form of an audio signal that has been encoded in digital form rather than analog form. In other words, music that has been processed by an analog-to-digital converter.

digital music aggregator – a company that gets music distributed through digital services, such as Spotify, Apple Music, iTunes, and Pandora. Because digital music providers normally do not deal directly with individual artists, a digital music aggregator provides the service of placing music on digital music stores and streaming platforms. Aggregators make their money by charging upfront fees, charging a percentage of revenue earned from streaming and downloading, charging an annual fee, or a combination of such fees. Called an aggregator for sort.

digital music file – see audio file.

digital music player – see digital audio player.

digital ouput – a connection that sends out digital audio signals. There are a number of digital output formats both optical and wired, including AES3 (AES/EBU), S/PDIF, ADAT, MADI, TDIF and others.

Digital Performer – a digital audio workstation developed by MOTU.

digital piano – an electronic musical instrument that simulates the timbre of an acoustic piano using digital samples of real pianos. It is sometimes confused with, but not the same as an electronic keyboard or electronic piano.

digital processor – see digital signal processor.

Digital Production Partnership (DPP) – a joint initiative of public service and commercial broadcasters in the UK formed to maximize the potential benefits of digital television (DTV) production.

digital radio – radio broadcasting using digital technologies, in which an analog audio signal is digitized, compressed, and transmitted using a digital modulation techniques. See DAB, DAR, DARS, DRM, and IBOC (HD radio).

digital recorder – a device that accepts one or more audio inputs and converts the audio into digital signals that are stored on a hard drive, flash drive, compact disccompact disc, or other digital medium. Some digital recorders have built-in microphones, but many simply have microphone inputs. They vary from fairly simple designs to very complex systems with multitrack recording capabilities and built-in effects. Included in this category are DTRs, such as DAT and DCC. Also called a digital audio recorder (DAR).

digital recording – the process of coverting an audio signal into digital data that can be stored on a hard drivee or other digital media, as opposed to analog recording in which the signal is stored as a continuous wave.

digital recording era – see digital era.

digital reverb – see algorithmic reverb.

digital revolution – see digital era.

digital rights management (DRM) – is a method used by hardware manufacturers, publishers, copyright holders, and others to control or limit the unauthorized use of digital content.

digital room correction – see room equalization.

digital sampling – (1) The process of taking a recorded portion from an existing recording and using it in a new recording. The section of recorded music, vocal, or spoken word is called a sample. Samples are often used in a repetitive manner, sometimes played backwards, or otherwise manipulated and sometimes used in combination with other sounds or samples. Because a copyright prohibits anyone from copying the original artistic work of another without consent, permission must be obtained from the copyright owner in order to use a sample. (2) The process of using a digital sampler to record a portion of an audio track and playing it back using an electronic keyboard or sampler. (3) Using recordings or samples of an instrument to be used to reproduce the sound of that instrument with an electronic keyboard or synthesizer.

digital sampler – see sampler.

digital signal – a signal that has been converted into a string of binary digits. Digital signals can be sent over longer distances with less interference than analog signals.

digital signal processing (DSP) – modifying a digitized sound wave using specialized software.

digital signal processor (DSP) – a specialized microprocessor that is optimized for digital signal processing.

digital summing – see summing.

digital synthesizer – see synthesizer.

digital tape – either digital audiotape or digital videotape.

digital tape recorder – either a digital audio tape recorder or a digital video tape recorder.

Digital Tape Recording System (DTRS) – a system using Hi 8 video cassettes to record digital audio, used for awhile by several manufacturers, but now mostly obsolete.

digital television (DTV) – the broadcasting of television in which the audio and video are transmitted using a digitally processed and multiplexed signal that is decoded at the receiving television set, in contrast with analog television that used separate analog video and audio channels. DTV broadcasts can be standard definition, intermediate definition, or high definition. Although all HDTV broadcasts are DTV, not all DTV is HDTV. There are four main standards for digital television terrestrial broadcasting (DTTB): (a) Advanced Television System Committee (ATSC) used in the United States, Canada, Mexico, South Korea, Dominican Republic and Honduras, (b) Digital Video Broadcasting-Terrestrial (DVB-T) used in Europe, Australia and New Zealand, (c) Integrated Services Digital Broadcasting - Terrestrial (ISDB-T) used in Japan and the Philippines, and a version designated ISDB-T International used in South America and some African countries, and (d) Digital Terrestrial Multimedia Broadcasting (DTMB) used in the People's Republic of China, Hong Kong, and Macau.

digital television terrestrial broadcasting (DTTB) – digital television transmitted using earth-bound stations, as opposed to direct-broadcast satellite (DBS).

digital-to-analog conversion – the process of changing a digital signal or data stream into an analog signal that contains essentially the same information, using an digital-to-analog converter. Abbreviated as DA conversion, D-A conversion, D/A conversion, and D-to-A conversion.

digital-to-analog converter – an electronic device or circuitry that converts a digital signal or data stream to an analog signal. Audio quality depends very greatly on the accuracy of the analog-to-digital converterand the digital-to-analog converter. Sometimes called a digital audio converter. Abbreviated as DA converter, D-A converter, D/A converter, D-to-A converter, and DAC.

digital-to-digital conversion – the process of changing a digital signal from one sampling rate to another and/or from one bit depth to another. The result is the same digital information using a different sampling rate and/or bit depth.

digital video – the capturing, editing, and storage of video in a digital format, as opposed to analog video, which uses analog signals.

digital videotape – magnetic recording tape used to record digital video.

digititus – a slang term for the perceived problems and shortcomings of digital audio as compared to analog audio.

digitization – any conversion of analog data into a digital format.

digitize – to convert analog data into a digital format.

dim – (1) A function found on some monitor controllers and the monitor control sections of consoles that reduces the level of the monitors by a preset amount to allow those in a control room to carry on a conversation without silencing audio playback. (2) The abbreviation for diminished,

diminish – to lower by one semitone.

diminished chord – see diminished triad or diminished seventh chord.

diminished fifth – an interval of six semitones. It is a semitone lower than a perfect fifth and is a tritone. An example is the interval from C to G♭.

diminished fourth – an interval of four semitones. It is a semitone lower than a perfect fourth and is enharmonically the same as a major third. Examples are the interval from C♯ to F and the interval form C to F♭.

diminished octave – an interval of eleven semitones. It is a semitone lower than a perfect octave and is enharmonically the same as a major seventh. Examples are the interval from C♯4 to C5 and the interval from C4 to C♭5.

diminished scale – a musical scale in which the octave is divided symmetrically into eight intervals with the step pattern tone-semitone-tone-semitone-tone-semitone-tone-semitone. For example, the C diminished scale is C-D-E♭-F-G♭-A♭-A-B-C. Also called the symmetric scale.

diminished second – an interval of zero semitones. It is a semitone lower than a minor second, and is enharmonically equivalent to a perfect unison. In other words, it is the interval between notes on two adjacent positions on the musical staff or notes having adjacent letters that are altered such that they have no difference in pitch. Examples are the interval from a B to the C♭ immediately above it and the interval from a B♯ to the C immediately above it.

diminished sixth – an interval of seven semitones. It is a semitone lower than a minor sixth, and is enharmonically the same as a perfect fifth. An example is the interval from A to G♭.

diminished seventh – an interval of nine semitones. It is a semitone lower than a minor seventh, and is enharmonically the same as a major sixth. An example is the interval from A to G♭.

diminished seventh chord – a four-note chord that consist of a diminished triad plus the interval of a diminished seventh (equivalent to a major sixth) above the root. It is (1, ♭3,♭5, ♭♭7), or enharmonically (1, ♭3, ♭5, 6), of a minor scale. For example, C diminished-seventh would be (C, E♭, G♭, B♭♭), or enharmonically (C, E♭, G♭, A). It occurs as a leading tone seventh chord in harmonic minor. It can also be viewed as four notes stacked in intervals of a minor third. The diminished seventh also contains two diminished fifths. A diminished seventh chord with root C is usually indicated as Cdim or C°, but in some modern jazz books and music theory literature Cdim, C7°, or Cm is used to denote a diminished triad, while Cdim7, C°7, or Cm6(♭5) denotes a diminished seventh chord.

diminished third – an interval of two semitones. It is a semitone lower than a minor third, and is enharmonically the same as a major second. An example is the interval from C to D.

diminished triad – a triad consisting of two minor thirds above the root. For example, a C diminished triad would have a C, an E♭, and a G♭. It resembles a minor triad with a flattened fifth. It is considered dissonant, or unstable, because the diminished fifth symmetrically splits the octave. The lack of a tonal center and having a leading tone and a dominant give the chord drive. For example, an A diminished chord contains the notes A, C, and E♭, and would want to resolve like an F7 dominant chord, which contains the same notes (F, A, C, and E♭). Diminished chords are mostly used in jazz, somewhat less so in classical music, but occasionally in pop music, especially when modulating between keys. Also known as a minor flatted fifth.

diminuendo – see decrescendo.

DIN – Deutsches Institut für Normung. The German national standards organization.

DIN connector – one of a group of round connectors originally standardized by DIN for analog audio signals. Some of these connectors have been adopted for other applications such as the 5-pin DIN connector for MIDI and several computer applications. These connectors are no longer inluded in the DIN standards, but the IEC has issued equivalent standards that replace them.
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DINR (Digidesign Intelligent Noise Reduction) – a noise reduction plugin developed by Digidesign (now Avid) that reduces unwanted noise, such as hiss, guitar-amp hum, and air conditioner rumble. DINR analyzes and subtracts noise entirely within the digital domain, to produce results that can be virtually free of artifacts, such as distortion, dynamic modulation (pumping and breathing), and undesired fluctuations in frequency response.

DIN stereo – see DIN stereo technique.

DIN stereo technique – a standard established by DIN for a stereo microphone technique that specifies two cardioid microphones 20 cm (7.9 inches) apart and angled at 90 degrees. Other systems use 110 to 120 degrees, but 90 degrees is considered easier to set up. It falls into the near-coincident pair category of techniques. Other techniques in this category include A-B, EBS, Faulkner array, NOS, ORTF, RAI. See also coincident pair (Blumlein array, mid-side, X-Y pair) and spaced pair (A-B, Decca tree, spaced cardiods, spaced omnis). See table comparing various stereo microphone techniques.

DIN sync – a mostly obsolete method for synchronizing virtual instruments that, for the most part, has been replaced by MIDI. It is called “DIN” sync because it uses the same 5-pin DIN connector as used by MIDI, but the two systems are not compatible. Sometimes called Sync 24 because it transmits at a rate of 24 PPQN.

DIN technique – see DIN, definition #2.

diode – an electronic component with two electrodes (an anode and a cathode), typically a semiconductor or vacuum tube. Diodes can be used as rectifiers, limiters, voltage regulators, switches, signal modulators, signal mixers, signal demodulators, and oscillators.

diode-bridge compressor – a type of audio compressor that uses a diode-bridge to provide variable gain-reduction of an audio signal. A diode bridge is an arrangement of four or more diodes in a bridge circuit that provides an output with the same polarity regardless of the polarity at the input. This compressor design, which was popular in the 1960s, provides a faster response than an opto-compressor and lower distortion than an FET compressor, but tends to be very noisy.

diotic – having the identical sound present in each ear, which is the opposite of dichotic.

dip – to decrease a range of frequencies with an equalizer. Used primarily in the UK along with lift for “boost.”

DIP switch – Dual Inline Package switch. A compact electric switch with small sliders that may be set to “on” (1) or “off” (0). This type of switch is typically used to customize settings in hardware devices. DIP switches are usually easier to use than jumper blocks.

dipole antenna – a type of antenna with two opposing radiating elements, that can be used for transmission or reception of radio signals.

dipole moment – see either electric dipole moment or magnetic dipole moment.

dipole speaker – a loudspeaker mounted on a flat panel, having two drivers that radiate sound equally in opposite directions. This design results in high frequencies being reflected from the rear wall creating more diffuse reverberations, resulting a more natural sound. For this reason dipole speakers are often used as surround channel speakers, because the diffuse sound creates a desirable ambience.

direct – (1) Using a direct intput. (2) Using a direct output. (3) Using direct recording. (4) Recording directly to a two-track master instead of mixing down multiple tracks, one for each performer.

direct box – see direct input box.

direct-broadcast satellite (DBS) – the broadcast of digital television programming directly for home reception. Another term which predates DBS is direct-to-home (DTH), which was initially used to distinguish the transmissions intended for home viewers from cable television distributors that sometimes use the same satellite. DTH is sometimes used for services carried by lower power satellites which required dishes 1.7 m (about 5 feet) in diameter or larger for reception. See also satellite television.

DirectConnect – the name given by Avid for a method of bringing an audio stream directly into Pro Tools using one of their audio cards.

direct coupling – see dc coupling.

direct current (dc) – an electric current that flows in one direction only. Officially abbreviated as dc, but commonly shown as DC. Contrast with alternating current (ac).

direct digital synthesizer (DDS) – a device that digitally creates analog waveforms from a fixed-frequency reference clock. A DDS can be used to generate signals, to replace phase lock loops, as an oscillator, and in sound synthesizers.

direct field – essentially the same as near field, although the name Nearfield® is a trademark of Edward M. Long of Calibration Standard Instruments (CSI) that has come into common usage. The term direct field is used with studio monitors so that the listener hears more direct sound than the reflected sound of the room with all its effects. This is better for mixing as it improves imaging and increases definition. Also called direct sound.

direct injection – see direct input.

direct injection box – see direct input box.

direct input – conncecting the output from an instrument, such as an electric guitar or electric bass, directly into a console or DAW without first passing through an amplifier/speaker and using a microphone. This is often done using a direct input box. Also called direct injection, direct recording or direct pickup.

direct input box – a device that converts high-impedance unbalanced audio signal into a low-impedance audio signal allowing you to connect an instrument (such as an electric guitar or bass guitar) directly into a DAW or console. Also called a direct box, direct injection box, DI box, or DI unit.

directional antenna – an antenna which transmits or receives more power in some directions more than others, which provides greater signal strength in those directions and reduces interference from other sources. Also called a beam antenna. See also antenna directivity.

directionality – see pickup pattern or radiation pattern.

directional microphone – a microphone that has a greater sensitivity from some directions more than others. Unidirectional microphones and bidirectional microphones are directional microphones. See also pickup pattern and polar pattern.

directional pattern – see pickup pattern or radiation pattern.

directivity – (1) A measure of the directional characteristic of a sound source. It is often expressed as a directivity index (DI), which is measured in decibels (dB), or as a directivity factor (Q), a dimensionless value. When a balloon is popped, it sends out a sound almost equally in all directions. This is equivalent to a Q value of 1. A person talking has a Q value of about 2, since the sound radiates in a hemispherical pattern (half a sphere). DI is equal to 10 time the logarythm of Q. Both directivy factor (Q) and directivity index (DI) are used to measure the directivity of loudspeakers and microphones (also called pickup pattern and polar pattern). See chart showing characteristics of directional microphones. (2) Antenna directivity.

directivity factor (Q) – see directivity.

directivity index (DI) – see directivity.

direct memory access (DMA) – a method that allows some hardware devices to access computer memory without using the central processing unit (CPU). DMA sometimes allocates channels, which can transfer data to and from devices faster than by using the CPU. There are a limited number of DMA channels, and only one channel can be used per device. A faster, enhanced versions of DMA is known as Ultra DMA (UDMA).

direct metal mastering (DMM) – a two-step process for vinyl mastering in which the master is created by cutting the audio signal directly into a copper-coated steel disc using a diamond stylus. vibrating at 60 kHz. The stamper is created directly from this disc. The usual three-step process cuts the audio signal into a lacquer-coated aluminum disc, from which electroforming is used to create an intermediate disc used to create stampers. See also lathe and vinyl mastering.

direct out – short for direct output.

direct output – a jack used to feed a signal directly from one device to another, such as from a mixer or guitar amp directly to a digital recorder or DAW. Also called a direct out or instrument out direct.

direct pickup – see direct input.

direct recording – see direct input.

direct sound – (1) A sound wave that travels straight from the source to the listener (or microphone) without reflecting or bouncing off any surfaces. Also called incident wave or incident sound. See also reverberation. (2) Another name for direct field or near field. (3) A sound recorded directly during the filming process, as opposed to being added later.

Direct Stream Digital™ (DSD™) – a joint trademark of Sony and Philips for their method of encoding the SACD format. Using pulse density modulation , the signal is stored as delta-sigma modulated audio with a sampling rate of 2.8224 MHz and a one-bit resolution. That is 64 times the sampling rate of CD audio (44.1 kHz), but ¹⁄16 the 16-bit resolution. It uses two file formats: DSDIFF (DFF) with the extension .dff and DSF, with the extension .dsf. There is also a higher rate version with a sampling rate of 5.6448 MHz (128 times the CD rate or Fs128), sometimes designated as DSD-128 or double-rate DSD. To distinguish it from the higher-rate version, the original DSD format (single-rate DSD) is designated as DSD-64 (Fs64).

Direct Stream Transfer™ (DST) – a joint trademark of Sony and Philips for a lossless data compression method used to reduce the space and bandwidth requirements of Direct Stream Digital (DSD) used in the SACD format. DST compression is compulsory for multi-channel audio, but optional for stereo. DST typically compresses by a factor of between two and three, which allows an SACD disc to contain up to 80 minutes with both 2-channel and 5.1-channel sound. Direct Stream Transfer compression was standardized as an amendment to the MPEG-4 audio standard in 2005.

direct-to-disc recording (DDR) – a recording method that bypasses the use of magnetic tape recording or digital recording methods and records audio directly on to an analog disc master.

direct-to-disk recording (DDR) – a recording method in which audio and/or video signals are recorded directly to a digital storage medium, such as a hard disk drive or an optical disc like a compact disc or DVD.

direct-to-reverberant ratio (DRR) – the ratio of the sound pressure level (SPL) of a direct sound (D) to the sound pressure level of the reverberant sound (R). The distance from the sound source at which the DRR equals 1 (D = R) is defined as the critical distance (dc). Also called direct-to-reverberation ratio.

DirectX – a collection of application programming interfaces (APIs) developed by Microsoft to perform a variety of multimedia tasks, such as music, video, and game programming, on the Windows platform. Originally, these APIs had names such DirectMusic, DirectSound, DirectPlay, and DirectDraw. The name DirectX began as a shorthand term for these APIs and eventually became the name of the collection.

DirectX plug-in – a plug-in format using the Microsoft DirectX API for use in DAWs, audio editors, and virtual synthesizers. DirectX plug-ins are similar to Virtual Studio Technology (VST) plug-ins and have an open standard architecture. There are two types of DirectX plugins: (a) DirectX effects plugins (DX) and (b) DirectX Instrument plugins (DXi). Effects plugins provide digital signal processing on audio signals, such as reverbs, delays, compressors, and limiters. Instrument plug-ins are MIDI-controllable and are used to synthesize sound or playback audio using virtual synthesizers, samplers, or drum machines.

dirt – slang for distortion, especially when referring to a guitar tone.

dirty – a descriptive term meaning distorted, whether intentional, such as a distorted guitar tone, or unintentional, such as an overdriven or clipped signal. The opposite of clean.

disable – the function in some DAWs of turning off a track or plug-in, so that it is not using CPU or DSP resources. The opposite of enable. Depending on the DAW this process may be referred to as deactivate, mute track with CPU-saving preference selected, or archive.

disc – (1) A flat circular object. The same as disk except disk usually refers to magnetic storage media (hard drives and floppy disks) while disc usually refers to optical storage media (CD and DVD). (2) A record in the form of a flat disc that for a time competed with the wax cylinder, but by the early 1920s eventually won the format war. Originally made of a shellac composition, they were later made of vinyl. Also called a phonograph disc or phonograph record.

Disc Description Protocol (DDP^®) – A standard protocol for describing the files and parameters needed to replicate compact discs and DVDs. It includes the content files, as well as additional files, such as table of contents, file structure, subcodes, indexing files, and other files that are needed to create a finished disc. This protocol makes it possible for a mastering house to send a complete disc definition to a pressing plant as a single file. DDP is a registered trademark of DCA, Inc.

disc drive – a storage device on a computer using magnetic storage media (hard drives and floppy disks) or optical storage media (CD and DVD). Note that disc usually refers to optical media while disk usually refers magnetic media.

disc jockey – a person who plays recorded music on the radio, at nightclubs, at discos, or at parties. Also called a deejay or DJ.

disclosure triangle – a small triangle you click to show or hide details or other choices in a user interface.

discography – a catalog of all recordings made by a particular performer or the works of a particular composer.

discordant – a sound that is harsh and lacks harmony.

discrete – consisting of distinct and unconnected parts. For example, in an audio context, the term is used to indicate that a circuit is made up of individual componets rather than using an integrated circuit. The term is also used to indicate separate and isolated channels are used rather than being combined using matrix encoding. The opposite of integrated.

discrete surround – a method of delivering surround sound in which each channel is separate from one another, as opposed to a matrix encoding, in which various channels are embedded into one or two main channels that have to be decoded when reproduced. Discrete surround provides better performance than matrix surround. Examples of discrete surround formats included Dolby Digital and DTS.

dished – a descriptive term for a sound with too much bass and treble, an exaggerated depth, and a lifeless quality due to a frequency response that is scooped out (dished) through out the entire midrange. Opposite of humped.

disk – a flat circular object. The same as disc except disc usually refers to optical storage media (CD and DVD) while disk usually refers to to magnetic storage media (hard drives and floppy disks).

disk drive – see disc drive.

diskette – see floppy disk.

dispersion – (1) The pattern and distribution of sound waves over an area. See also radiation pattern. (2) The distribution of the particles of magnetic coating within the binder on a recording tape. Good dispersion is having an equal number of particles within each extremely small volume of coating. Dispersion affects particle orientation, surface smoothness, and modulation noise. Also called particle dispersion. (3) Short for dispersion pattern (radiation pattern).

dispersion angle – the angle of effective coverage of the sound projected from a loudspeaker, defined as the area between the angles at which the SPL of the speaker is 6 dB lower than its on-axis level, in both a vertical and horizontal direction. The angles vary with frequency. Speaker specifications usually list both horizontal and vertical dispersion angles. See also radiation pattern.

dispersion pattern – see radiation pattern.

displacement sensitivity – the distance that a key is pressed down on a keyboard. Displacement-sensitive keyboards are often found on organs. The distance the key is pressed can produce a different volume, pitch, or tone. See also keyboard expression.

display – an electronic device for the visual presentation of data or graphics. Sometimes called a video display or video display unit (VDU).

DisplayPort (DP) – a digital interface primarily used to connect video to a display, such as a computer monitor. It can also carry audio, USB, and other data. The DisplayPort was developed by a consortium of computer and chip manufacturers and standardized by the Video Electronics Standards Association (VESA). See also mini DisplayPort

display resolution – see resolution, definition #2.

dissonance – in music, a sound that is not consonant. However, the term is used to describe a gradation from the most consonant to the most dissonant sounds or intervals. The opposite extreme is consonance.

dissonant – a sound that lacks harmony or that is harsh or discordant.

distance factor – the relative distance of a directional microphone as compared to an omnidirectional microphone to reach critical distance.

distant miking – a technique that places one or more microphones at some distance from the performers. This technique allows coverage of a greater area with fewer microphones, but does not have the presence and detail possible with close miking. Sometimes spot miking (accent miking) is used with distant miking to to add presence or to improve clarity, blending, and tonal balance. Also called distant pickup. Sometimes spelled distant micing or distant mic'ing. See also ambient microphone.

distort – to change an audio signal in any way. See distortion.

distortion – any change in an audio signal, whether it produces a pleasant or unpleasant sound. While we usually think of distortion as unpleasant, some distortion is intended, such as with distortion effects, and some distortion is desirable, such as the introduction of harmonics to create a “warm” sound. There are many types of distortion, which generally can be divided into three groups: (a) linear distortion, which occurs when the amplitude of the output signal is not proportional to the amplitude of the input signal, (b) nonlinear distortion, which occurs when new frequency components are generated, and includes harmonic distortion and intermodulation distortion, and (c) time-based distortion, which includes phase shift, wow, flutter, and reverberation. See also coloration.

distortion effect – an effect that produces intentional distortion, with parameters to control the amount and type of distortion. Distortion effects are used for guitar effects and in some digital plug-ins.

distortion synthesis – a type of sound synthesis that modifies existing sounds to produce more complex sounds (or timbres), usually by using nonlinear circuits or algorithms.

distributed-mode speaker panel – see flat-panel loudspeaker.

distribution amplifier – an amplifier with balanced inputs and outputs and high-current drivers designed to handle long lines with many speakers.

dither – the process of adding a small amount of noise to a signal when converting from one sample rate and/or bit depth to another in order to minimize digital errors.

DI unit – see direct input box.

dive bomb – an electric guitar technique in which the tremolo bar is depressed rapidly while a note is sustaining to create a large drop in pitch, sometimes an octave or more, which resembles the dropping of a bomb. Sometimes spelled divebomb.

diversity – a system used with wireless microphones to improve reception and minimize signal dropouts by sending redunctant signals by various means. There are several methods of achieving diversity including, time diversity, frequency diversity, space diversity, and antenna diversity. A regular wireless system that uses none of these methods is now referred to as non-diversity. See also true diversity and antenna diversity.

divided pickup – an instrument pickup that has separate outputs for each string, typically used with pitch-to-MIDI converters. They also allow separate processing and amplification of each string. Also called hexaphonic pickup (for six strings, as on a guitar) or polyphonic pickup.

DJ – Disc Jockey.

djembe – a rope-tuned, skin-covered goblet-shaped drum played with the hands, originally from West Africa. Sometimes spelled djembé, jembe, jenbe, djimbe, jimbe, or dyinbe.

DJ mixer – an audio mixer used by DJs to make smooth transitions between different sound recordings while they are playing. The recording sources can be record turntables, cassettes, drumCDs, or digital audio files using DJ software on a laptop computer. Sometimes spelled deejay mixer.

DLS – DownLoadable Sounds. A collection of standards for file formats of digital music virtual instrument programs. The DLS standards also include specifications for the way MIDI-controlled synthesizers playback the instruments contained in a DLS file.

DLT – Digital Linear Tape. A computer data storage and retrieval system developed by Digital Equipment Corporation that uses a proprietary ½-inch tape cartridge.

DMA – Direct Memory Access.

DMB – Digital Multimedia Broadcasting.

DME – Dialog, Music, and Effects. The three basic tracks that makeup a motion picture soundtrack. See also M&E. Soundtracks are sometimes divided into five elements: dialog (including narration), music, sound effects, ambient sound (sometimes included with sound effects), and Foley. See also sound design.

DMM – Direct Metal Mastering.

DMP – Digital Media Player.

DMX (Digital MultipleX) – a protocol originally developed for controlling stage lighting, but later expanded for use with fog machines and other devices. The signal is unidirectional, meaning it travels in only one direction, from the controller and then from light to light to the final light or device. The standard protocol, DMX512, was developed by the Engineering Commission of United States Institute for Theatre Technology (USITT) in 1986, and revised in 1990. In 2004 it was revised and adopted as an lossyANSI standard E1.11, which was revised in 2008. A DMX controller is used to program and control devices. The DMX512 standard specifies the use of five-pin XLR-style cables (XLR-5), with the three-pin XLR connector specifically prohibited. However, the three-pin XLR connector is commonly used for budget and DJDJ lighting and control equipment.

DMX512 – see DMX.

DN – Dialog Normalization.

DNR – Dynamic Noise Reduction.

DNxHD – Digital Nonlinear Extensible High Definition. A lossy, high-definition, video, codec, developed by Avid, that can be used both during editing and as a presentation format. DNxHD data is usually stored in an MXF, container, but can also be stored in a QuickTime (.mov) container. In 2008, DNxHD was standardardized as SMPTE VC-3. Although DNxHD is intended to be an open standard, it essentially has remained a proprietary Avid format, as commercial use require licensing by Avid. Sometimes shown as DNX HD.

DOA – (1) Discrete Operational Amplifier. An operational amplifier built using discrete transistors, as opposed to using an integrated circuit. (2) Dead On Arrival. The situation in which a piece of equipment that has been ordered online or by mailorder has been received broken or in a non-functioning condition.

Dobro^® – a trademark of the Gibson Guitar Corporation for their version of a resonator guitar. The name is a contraction of the Dopyera brothers, who founded the National String Instrument Corporation in 1927 and the Dobro Manufacturing Company in 1928. In 1932, National and Dobro merged to form the National Dobro Corporation, which was acquired by Gibson in 1994. Dobro is sometimes used as a term for any resonator guitar. However, the term National is also used to distinguish the designs created by the National String Instrument Corporation from those of Dobro.

doghouse – an extended portion of a mixer case that allows cables to be connected to the back of the mixer while the mixer is sitting in the case. Typically the top lifts off the bottom portion of the mixer case, and the doghouse swings or folds up and over connected cables to protect them while still allowing access to the connections.

doghouse bass – slang term for a double bass. According to journalist Tom Wheeler, after Leo Fender invented the electric bass, he said, “We needed to free the bass player from the big doghouse, the acoustic bass. That thing was usually confined to the back of the band, and the bass player couldn't get up to the mic to sing.”

Dolby – one of several processes created by Dolby Laboratories, Inc. to reduce background noise in tape recordings, to encode surround sound, to compress sound, and to digitize sound. The term Dolby is often used to mean one of the Dolby noise reduction systems for tape, which are usually designated as Dolby A, Dolby B, and Dolby C.

Dolby A – see Dolby noise reduction.

Dolby AC-3 – see Dolby Digital.

Dolby AC-4 – a digital audio data compression technology developed by Dolby Labs for 5.1 surround sound. AC-4 bitstreams can contain audio channels and/or audio objects and requires a Dolby AC-4 decoder to decode the signal. The ATSC selected Dolby AC-4 as one of the three standards for the audio in ATSC 3.0.

Dolby Atmos – an immersive audio format developed by Dolby Laboratories in 2012. The Atmos technology uses object-based audio, which allows for an unlimited number of audio tracks to be distributed to theaters for optimal presentation to speakers based on the theater capabilities. Ambient sounds are separately pre-mixed in a traditional multichannel format, but during playback the Atmos system mixes and renders the sounds in real-time to make each sound seem to be coming from a designated spot, depending on that particular theater's speaker configuration.

Dolby Atmos Mastering Suite – a set of tools developed by Dolby Labs to create, edit, mix, and master high-quality Dolby Atmos content for Blu-ray and digital distribution for home entertainment. It is designed to work with Dolby-approved hardware to run as a home theater rendering and mastering unit (Home Theater RMU). It includes Dolby Atmos Home Theater Renderer software for Windows on a Dolby Atmos RMU, the Dolby Atmos Production Suite for Mac, and the Dolby Atmos Conversion Tool.

Dolby Atmos Production Suite – a plug-in (currently only for the Mac version of Pro Tools) for creating and mixing Dolby Atmos content for film, TV, VR, and linear gaming production. It includes the Dolby Atmos Renderer for Mac, the Dolby Atmos Panner plug-in, Atmos VR Spherical Panner plug-in, the Dolby Atmos VR XYZ Panner plug-in, the Dolby Renderer Send plug-in, the Dolby Renderer Return plug-in, the Dolby Atmos Monitor, and the Dolby Atmos VR Transcoder.

Dolby Atmos speaker layout – the Dolby-recommended arrangement for both mixing and playback. Dolby recommends a 7.1.4 arrangement for mixing. An equidistant layout in which the satellite speakers are located on the surface of an imaginary sphere with the listening position at the center is considered ideal. However, because most mixing and listening rooms are in rectangular-shaped spaces, an orthogonal arrangement is an acceptable alternative.

Dolby B – see Dolby noise reduction.

Dolby C – see Dolby noise reduction.

Dolby Cat 43 – a noise-reduction system developed by Dolby Labs. The unit consisted of a rack-mounted system containing four Dolby A cards, one for each of four frequency ranges. The Cat 43 evolved from Dolby A, which originally was a four-band, encode-decode, compression-expansion system. It was discovered that Dolby A was also useful when used in the decode-only mode, in which case it acted like a four-band downward expander, reducing quieter sounds while leaving louder sounds unaffected. The the Cat 43 system became very popular in TV and movie post production to remove unwanted ambient noise from location dialog soundtracks.

Dolby Digital (DD) – a digital audio data compression algorithm developed by Dolby Labs for 5.1 multichannel audio in HDTV transmission, DVDs, and CDs. It goes by a variety of names and abbreviations such as AC-3 (Audio Codec 3, Advanced Codec 3, Acoustic Coder 3) and DD.

Dolby Digital EX – a surround sound format developed by Dolby Labs that is similar in to Dolby's earlier Pro Logic format, that adds a matrixed center surround channel and matrixed rear channels, to create 6.1 or 7.1 channel output.

Dolby Digital Plus (DD+) – a successor to Dolby Digital developed by Dolby Labs for the transport and storage of multichannel digital audio, that has a number of improvements including support for more data rates (32kbit/s to 6144kbit/s), increased channel count, and multi-program support.

Dolby E – an audio encoding and decoding method developed by Dolby Labs that provides for 6 to 8 channels of audio that can be compressed into a standard pair of digital stereo audio tracks and transmitted using the AES3 (AES/EBU) standard. Dolby E is designed for use by post-production and broadcast facilities. Audio transmitted in the Dolby E format is encoded with Dolby Digital prior to final transmission to the consumer.

Dolby-Encoded Stereo (DES – a noise reduction system developed by Dolby Labs for use on the stereo optical tracks in movie theaters.

Dolby HX – see Dolby HX Pro.

Dolby HX Pro – electronic circuitry, developed by Jørgen Selmer Jensen of Bang & Olufsen in 1980, that dynamically reduces the tape bias signal in the presence of strong high-frequency signals during analog tape recording. A strong high-frequency signal, such as that of a high-hat, adds to the normal tape bias which can cause magnetic saturation on the tape. Dynamically adjusting the recording bias level in the presence of such signals counteracts this self biasing. The process, which is known as high-frequency compression, greatly improves headroom, making it possible to record at higher levels, thereby increasing the signal-to-noise ratio. After B&O modified the process for consumer equipment, it licensed it to Dolby Laboratories, who began marketing it in 1982 as Dolby HX (for consumer recording machines) and Dolby HX-Pro (for professional machines). HX stands for Headroom eXtension. Being a record-only process with no known negative side effects, it is active at all times on machines that are equipped with HX or HX Pro.

Dolby Laboratories, Inc. – a company founded in 1965 to develope noise reduction systems. They have gone on to created many advancements in sound technology, including noise reduction systems, stereo and surround sound encoding, and digital media data compression and reproduction. The word Dolby is frequently used generically to refer to noise reduction.

Dolby Motion Picture 4:2:4 – a matrixed surround-sound system develped by Dolby Labs in 1977 for the first ”Star Wars” movie. It encodes 4-channel audio (left, right, center, and sides) into a two-channel, stereo-compatible format that can be broadcast or recorded and susequently decoded back into four channels. Because matrix systems cannot completely eliminate crosstalk, the decoder overcomes the problem with a process that emphasizes the signal sent to the appropriate loudspeaker and minimizing the crosstalk in adjacent channels.

Dolby noise reduction (Dolby NR) – several processes developed by Dolby Labs for removing unwanted noise when using analog magnetic recording tape. Dolby's first noise reduction system was Dolby A, which was released in 1965. Intended for use in professional recording studios, it splits the signal into four frequency bands and provides about 10 dB of noise reduction, which increases to about 15 dB at 15 kHz. Dolby B was released in 1968 for consumer tape decks. It is a simpler, less expensive system using a single-band in the higher frequencies and provides about 10 dB of noise reduction. Dolby C was introduced in 1980 for consumer tape decks (primarily higher end) and has two bands (essentially using Dolby B twice), which is extended to lower frequencies and provides about 15 dB of noise reduction. Dolby SR (for Spectral Recording) was introduced in 1986 for professional recording studios. It uses a complex series of filters that change with the input signal providing up to 25 dB of noise reduction in the higher frequency range, as well as other innovations. Dolby S was introduced in 1989 for use on commercial pre-recorded cassettes. It is a less complex version of Dolby SR that uses many of the same noise reduction techniques. Dolby S is capable of 10 dB of noise reduction at low frequencies and up to 24 dB of noise reduction at high frequencies. Because it was introduced to the market when the compact disc was becoming the major music format, Dolby S was never widely used.

Dolby Pro Logic – an advancement over Dolby Surround, this second generation surround sound format for the home was a 5-channel matrix system that provided an active center channel with its own speaker that its predecessor did not have.

Dolby reference level – a standard level established by Dolby Labs for playing audio systems in homes, theaters, and other venues. With the volume control set a 0 dB with a test tone, the volume at the listening position measured on an SPL meter should be 85 dB-SPL from the left and right speakers, with peaks up to 105 dB. The volume from the LFE channel can be up to 115 dB. Some systems automatically add 10 dB to the LFE channel, but others allow it to be set. THX requires internal test tones to be at -30 dB and nearly all systems use that level whether they are THX-certified or not.

Dolby Rendering and Mastering Unit (RMU) – the hardware and software tools required to produce a digital cinema package (DCP) using Dolby Atmos for theatrical productions. The Dolby RMU is only available from Dolby and requires room certification by a Dolby representative or agent. The RMU renders a 7.1.2 Atmos bed and the required panning metadata.

Dolby S – the consumer version of the Dolby SR system introduced in 1989. Intended primarily for high-end cassette decks, Dolby S provided the home consumer the ability to record on cassettes with sound quality approaching that of compact discs. Using a less complex version of Dolby SR, Dolby S is capable of 10 dB of noise reduction at low frequencies and up to 24 dB of noise reduction at high frequencies. Because it was introduced to the market when the compact disc was becoming the major music format, Dolby S was never widely used.

Dolby SR – a signal processing system introduced by Dolby Labs in 1986 for use in professional recording studios. It provided improved noise reduction over past systems (up to 25 dB of noise reduction at higher frequencies), and it also included several other technological innovations such as extended dynamic range, anti-saturation, spectral skewing, and modulation control. Dolby SR (for Spectral Recording) made it possible to create very high quality master recordings almost approaching digital quality. Because Dolby SR was introduced shortly after some of the first digital machines arrived, it helped keep analog recording alive for a few more years.

Dolby SR•D – a term used by the movie industry to designate a 35-mm print release with both an analog Dolby SR (SR) and a digital Dolby Digital (D) soundtrack. Sometimes used incorrectly for a Dolby Digital only release.

Dolby Stereo – a matrix technology developed by Dolby Labs that provided a method for movie makers to put 4 channels of sound onto motion picture film. The four channels included left, right, center, and surround. This was later released for the home market as Dolby Surround.

Dolby Surround – a 4-channel matrix-encoded surround technique licensed by Dolby for the home market that contained the same channels as the original motion picture release.

Dolby tone – a reference tone, usually recorded at the beginning of a Dolby A-encoded recording tape, used to adjust the threshold levels of the Dolby noise reduction system.

Dolby TrueHD – a lossless multichannel audio codec developed by Dolby Labs used in home-entertainment equipment such as the Blu-ray Disc, which is a successor to the AC-3 Dolby Digital codec that was used with DVDs.

Dolby Virtual Speaker – an algorithm devloped by Dolby Labs that emulates the surround-sound effects of a 5.1-channel speaker system using only two speakers. The technology uses psychoacoustic, biological, psychological, and physical principals to create the impression of additional speakers placed for a surround sound system having five actual speakers.

Dolby Vision – a technology developed by Dolby Labs for the creation, production, transmission, and playback of video content for theaters, television broadcasting, and internet streaming that includes high dynamic range imaging (HDR) and a wide color gamut. See also ultra-high-definition television (UHDTV).

domain – the smallest particle on a magnetic recording tape, that can be considered as a separate magnet, typically one molecule of ferric oxide, chromium dioxide, or powdered metal, weighing less than one billionth of a gram. See Barkhausen effect.

dome – see dust cap.

dome tweeter – see tweeter.

dominant – the fifth note or fifth degree of a diatonic scale. It is called “dominant” because it is the next most important note to the tonic. A dominant chord is the triad formed using the dominant pitch along with other notes of the same diatonic scale. The dominant chord is usually symbolized by the Roman numeral V (a major chord) in a major scale or v (lower case indicates that the chord is a minor chord) if it is in a minor scale. Also called a dominant note or dominant tone. See also tonic, supertonic, mediant, subdominant, submediant, leading tone, and octave.

dominant chord – see dominant.

dominant key – the key whose tonic is a perfect fifth above (or a perfect fourth below) the tonic of the main key in a given musical composition. For example, if a piece is written in the key of C major, the tonic key is C and the dominant key is G major, because G is the tonicdominant note for the key of C major. On the circle of fifths, the dominant key is the key immediately clockwise from any given key. The dominant key has either one more sharp or one less flat than the tonic key.

dominant note – see dominant.

dominant tone – see dominant.

dongle – a copy protection device that plugs into a USB, parallel, or other port on a computer that allows access to a particular program or plug-in. If the dongle is not present, the program will not run.

Doppler distortion – a type of distortion that occurs when a speaker cone simultaneously reproduces low-frequency sounds and high-frequency sounds. As the speaker cone moves slowly back and forth with the low frequency it is vibrating more rapidly at the high frequency. Just as the pitch of a moving car horn seems higher when it is moving toward you and lower as it moves away (the Doppler effect), so the motion of the cone caused by low frequencies will modulate the frequency of the higher pitched sounds. There is some argument as to whether Doppler distortion even exists, while others claim it is the same as phase modulation.

Dorian mode – one of the seven musical modes or scales with the interval pattern of tone-semitone-tone-tone-tone-semitone-tone.

dot markers – see fret markers.

dotted note – a musical notation that consists of a note followed by a small dot that indicates the duration of the note should be increased by half its original value. For example, a dotted half note would be three beats instead of the usual two, and a dotted quarter note would have a duration of 1½ beats instead of the usual one (both examples indicated for 4/4 time.

double – short for double tracking.

double bar – a musical notation consisting of two vertical lines that occurs in a piece of music indicating the end of a section, movement, or complete work. A double bar preceded by two dots, one over the other, indicates that the section is to be repeated, and is called a repeat mark.

double bass – the largest and lowest-pitched string instrument of the violin family. It is normally a four-string instrument usually played with a bow while standing upright, but can be plucked or slapped. It is a half octave lower than a cello, but it is transposed by one octave (written one octave higher than it is played). Also called a string bass, upright bass, stand-up bass, bass violin, bass fiddle, acoustic bass, contrabass, big bass, doghouse bass, or bull fiddle.

double-button carbon microphone – see carbon microphone.

double-blind comparator – a type of testing in which a subject hears audio sample A, then audio sample B, followed by audio sample X. The subject must determine whether X is A or B. It is a double-blind test because neither the tester nor the subject knows which source is A, B, or X. Also called ABX testing or sometimes ABY testing.

double-braided shield – a type of cable shield that consists of two layers of braided strands of copper that surrounds the insulated center conductors of a cable. A double-braided shield provides higher RFI shielding than single-braded shielding, but not quite as flexible and at a higher cost. French Braid™ is a trademark of Belden for a type of double-braided shield consisting of a two spiral braids woven together in a single weave. A French Braid shield provides great structural integrity and is extremely flexible, but at a higher cost than regular double-braided shielding. See also foil shield, braided shield, spiral shield, and double-spiral (Reussen) shield.

double bussing – feeding two or more multitrack inputs from one output.

double coil – see humbucking coil.

double-diode tube – see twin-diode tube.

double fast – a method of transmitting audio at a higher data rate than the AES3 (AES/EBU) standard maximum rate of 48 kHz by doubling the rate to 96 kHz. Another method of transmitting high bandwidth AES3 signals is double wide, which transmits the data over two cables. Neither method is compatible with the other.

double flat – the equivalent of two flats (♭♭), which lowers the pitch of a note by two semitones or one whole step. Double flats are used to indicate accidentals in a flat key or altered pitches in a chord. The double-flat symbol () is placed before a note like other accidentals. Although a double-flatted note in a chord such as D can be indicated as one note lower (C), it would make the notes in the chord appear odd.

double-headed – a drum that had a head on both the top and bottom.

double-lapped shield – see double-spiral shield.

double mid-side array – a surround sound microphone technique that extends the mid-side stereo microphone technique to surround sound, as well as other applications. It uses two cardioid microphones, one facing front and one facing backward, each shared with one side-facing figure-eight microphone. The recorded tracks can be decoded by sums and differences of the microphone signals into the left front, right front, left side, and right side. This technique also allows for post recording changes to the pickup angle. Many of the other surround sound techniques occupy a considerable amount of space, making them inconvenient for field recording. However, the double mid-sdie technique is quite compact. Also called double MS, double M-S, double M/S, MSM, or Mid-Side-Mid.

double M-S – see double mid-side. Also written double MS or double M/S.

double ORTF – a surround sound microphone technique used for the pickup of ambience based on the ORFT (Office de Radiodiffusion-Television Francaise) stereo technique. It consists of four cardioid microphones placed in a rectangular formation, with front and rear arrays angled at 110 degrees from one another and 17 cm (7 in) apart. The rear array is 25 cm (10 in) behind the front array. It is essentially an ORTF configurations placed back-toback. Compare with the IRT cross, which some people have claimed as being a double ORFT.

double-rate DSD – see Direct Stream Digital.

double-Reussen shield – see double-spiral shield.

double-serve shield – see double-spiral shield.

double sharp – the equivalent of two sharps (♯♯), which raises the pitch of a note by two semitones or one whole step. Double sharps are used to indicate accidentals in a sharp key or altered pitches in a chord. The double-sharp symbol () is placed before a note like other accidentals. Although a double-flatted note in a chord such as C can be indicated as one note higher (D), it would make the notes in the chord appear odd.

double sideband (DSB) – see sideband.

double-sideband amplitude modulation (DSB-AM) – see sideband.

double-spiral shield – a type of cable shield, consisting of two overlapping shield layers, spiral-wound in opposite directions so that the strands of each layer are at 90-degree angles to one another. This arrangement provides improved shielding over single layers, makes the shield slightly less likely to unravel, and allows the cable to be rather flexible. Also called Reussen shield (pronounced roy-sen), double-Reussen shield, double-serve shield, or double-lapped shield. See also foil shield, spiral shield, braided shield (mesh), and double-braided shield.

double-system sound – a method of recording sound for motion pictures in which the sound is recorded on magnetic recording tape separately from the picture. The sound and picture are synchronized later using timing tracks or timecodes. See also single-system sound.

double tracking – (1) Recording a vocal on one track and then re-recording the vocal (in a separate performance that closely matches the first) on a second track. Sometimes called re-tracking, stacking, layering, or doubling. See also quad tracking and ins and outs. (2) A special effect that simulates the effect of double tracking by combining a signal with a duplicate signal that is slightly detuned and/or delayed by 15 to 35 milliseconds. Sometimes called automatic double tracking.

double wide – a method of transmitting audio at higher than the the AES3 (AES/EBU) standard maximum rate of 48 kHz by splitting the audio into two data streams that are transmitted separately over two cables. Another method of transmitting high bandwidth AES3 signals is double fast, which essentially doubles the data rate of an existing single channel data stream sending it over one cable. Neither method is compatible with the other.

doubling – see double tracking.

download – (1) To transfer data from a larger to a smaller computer (often from the internet), from a distant to a nearby computer, or from a computer to another device. (2) Data that has been transferred in such a manner. (3) The process of transferring such data. The opposite of upload.

downmix – to mix a number of distinct audio channels into a lower number of channels. See also mix down. Also called fold down.

downsample – to convert from a higher sampling rate to a lower one, such as converting audio at 88.2 kHz to 44.1kHz to meet the standard compact disc sampling rate. Sometimes written as down sample.

downward compressor – see low-level compressor.

downward expansion – see expansion.

DP – DisplayPort.

DPA Microphones, Inc. – a company headquartered in Longmont, CO, that designs and manufactures professional microphones. It has its roots in Brüel & Kjær, a company begun in Denmark in 1942 for sound and vibration measurement. In 1992, Ole Brøsted Sørensen and Morten Støve, left Brüel & Kjær and founded DPA using their knowledge of measurement microphones to design and produce pro-audio microphones. In 2018, DPA was acquired by the RCF Group.

DPCM – Differential Pulse Code Modulation. See pulse code modulation.

DPD – Digital Phonorecord Delivery or Digital Permanent Download or Digital Product Download. A digital download of a sound recording containing music (phonorecord) delivered from the internet. DPDs may be stored on the computer of the recipient indefinitely or they may be transferred to portable devices or burned onto compact discs (as allowed by the distributor of a specific DPD). Just as with physical copies of musical works, DPDs must have mechanical licenses. Also called a digital mechanical license. See also digital distribution.

DRACULA – Dynamic Range Audio Controller with Unobtrusive Level Adjustment. The BBC system for reducing the dynamic range of musical programming on AM and FM broadcasts.

drain wire – a ground or shield wire.

DRAW – Digital Read After Write or Direct Read After Write. A technique that allows monitoring of what is being recorded as it is being recorded. The CD-RW (re-recordable compact disc) can use DRAW, but the technique is rarely used except for some digital tape systems.

dread – slang for dreadnought.

dreadnought – a style of acoustic guitar originally developed in 1916 by C. F. Martin & Company. The design had a square bottom and shoulders with a larger body than most other guitars at that time, which provided a louder sound. The term dreadnought referred class of battleship of the type initiated by the HMS Dreadnought in 1906. The dreadnought is now a common style of guitar, having been copied by other guitar manufacturers. Also called a D-size or dread for short.

drip – short for reverb drip.

DRIR – Directional Room Impulse Response. An impulse response used to capture acoustic characteristics of a given space. This data is useful when working with Ambisonics and audio for Virtual Reality (VR). See also BRIR.

drive – (1) The mechanism that propels, moves, or transports an object, such as the mechanism that moves the recording tape in a tape machine, turns the platter of a turntable, or spins a compact disc in a CD player. (2) To propel, move, or transport an object. (3) To supply a signal to, such as to drive an amplifier or loudspeaker. (4) A storage device for a computer, such as a disc drive or thumb drive.

driven shield – a shield on a cable that instead of being grounded has the same voltage as the signal, which reduces capacitance and signal leakage effects.

driver – (1) The transducer or active element within a speaker cabinet that converts electrical energy into sound waves. They typically consist of one or more of a woofer, midrange driver, and tweeter. Sometimes called a drive unit. (2) The transducers in headphones that convert electrical energy into sound waves. There are several types of headphone drivers. Sometimes called drive units. (3) Short for device driver.

drive unit – see driver, definition #1.

drone cone – see passive driver.

drop – see smack.

drop-frame time code (DFTC) – a method of correcting the difference between the NTSC color video frame rate of 29.97 frames per second (fps) when playing video with a frame rate of 30 fps. The 30 fps NTSC video frame rate was changed to 29.97 with the advent of NTSC color for technical reasons, but the 0.03 fps amounts to an error of 3.59 seconds each hour. Drop frame time code was developed to handle this discrepancy. This procedure drops frame numbers 0 and 1 of the first second of every minute, except when the number of minutes is divisible by ten. See 3:2 pull down.

drop in/out – see punch in/out.

dropout – (1) A momentary loss of signal during playback of a tape recording caused by an irregularity, such as loss of magnetic coating, loss of contact between the tape and the head, or the presence of dirt or dust on the tape. (2) A momentary loss of the audio signal when using a wireless microphone, due to RF interference or multipath reflections distorting the radio signal.

dropped tuning – see alternate tuning.

DRM – (1) Digital Rights Management. (2) Digital Radio Mondiale. Digital audio broadcasting technologies being used in Europe on the existing AM broadcasting bands, especially shortwave. (Mondiale is Italian and French for “worldwide”).

Dr Pepper setting – slang for a common starting point setting for the 1176 compressor. The name is taken from an early Dr Pepper label which had the numbers 10, 2, and 4 positioned around a clock. Many engineers found that placing the attack control at 10 o'clock, the release at 2 o'clock, and the ratio at 4:1 yielded excellent results.

DRR – Direct-to-Reverberant Ratio.

drum – a percussion instrument typically cylindrical, barrel-shaped, or bowl-shaped with a membrane stretched tightly over one or both ends, played by beating with the hands, sticks, or brushes. There are many types of drums including the snare, tom-tom, bongos, cajón, conga, djembe, tabla, timpani, and many others.

drumbeat – (1) A stroke on a drum. (2) The sound of a drum being struck. (3) A series of drum strokes. (4) A drum pattern. Sometimes spelled drum beat.

drum booth – an isolation booth or a small room used as an enclosure for recording drums and other percussion instruments, to avoid the bleed into microphones of other instruments being recorded at the same time. Some drum booths are not fully enclosed and do not provide complete isolation, but avoid the problem of standing waves and midrange resonances that can give small rooms an unnatural, boxy sound. Also called a drum room.

drum felt – a strip of felt that can be affixed to a drumhead to eliminate ringing or other unwanted tones.

drum fill – an improvisational solo played by the drummer between melodic phrases or during a transition in the music.

drumhead – the membrane or skin of a drum. They come in several varieties: (a) Single ply, typically made from one layer of 7-mil Mylar, the thinnest drum heads. Designed for light hitters, they produce high-end frequencies and their pronounced tones are useful in arena rock shows as well as quiet jazz ballads. (b) Double ply, made of two layers of 7-mil Mylar. The two layers of Mylar provide more attack and better control of the sound and are usually better in recording studio applications. (c) Coated, having an application of some form of dampening material. The coating softens the sound of the head producing a warmer sound. (3) Pre-muffled, with foam or other damping material to suppress undesired frequencies. Useful on kick drums to prevent ringing in order to achieve a nice blend of the “thud” of the drumhead and “thwack” of the beater against the batter head. Called a head for short. Sometimes spelled drum head.

drum hoop – see rim.

drum key – a T-shaped wrench used to adjust the tension rods of a drum, to adjust its pitch, and to loosen the rim in order to change the head. Also called a drum tuning key.

drum kit – a set of drums, cymbals, and other percussion instruments used by a drummer and played with drumsticks or brushes. Although they vary with the drummer, a typical drum kit consists of a foot-operated kick drum (bass drum), a snare drum, hihat, one or more cymbals, and one to four tom-toms. Also called a drum set, trap set, or trap kit.

drum machine – an electronic device that can be programmed to play digitized drum sounds.

drum miking techniques – the way in which microphones are placed to record a drum kit. Several techniques, using anywhere from a single microphone to many microphones, are shown below:
   (1) Single microphone techniques: (a) one condenser microphone 6 feet high and 2 to 3 feet in front of kit, (b) one condenser microphone behind the kit, 6 feet high pointed at the kit, (c) one overhead microphone about 4 feet above the kit, (d) one condenser microphone about 8 feet in front of the kit.
   (2) Dual microphone techniques: (a) X-Y pair, (b) ORTF, (c) spaced pair, (d) M/S stereo technique, (e) baffled microphone technique, (f) one overhead condenser microphone pointing at the drum kit and one dynamic microphone on the kick drum (the Ringo Starr setup).
   (3) Three-microphone techniques: (a) Decca tree, (b) Motown drum technique, (c) X-Y pair plus kick.
   (4) Four microphone techniques: (a) Glyn Johns method, (b) Recorderman technique, (c) X-Y pair plus kick and snare.
   (5) Multiple microphone techniques: dynamic microphones on snare, kick, each tom, plus two condenser overhead microphones. Possible additional mics can include high-hat, snare bottom (with reverse polarity), and one or more room microphones.
   (6) Special techniques for specific drums:
      Snare drum: (a)  Miking top and bottom using two dynamic mics, typically SM57s, with the polarity of the bottom mic being reversed. (b) Miking the top of the snare using two mics, one dynamic and one small diaphragm condenser. (c) A large-diaphragm condenser mic at the side of the snare drum, which captures the top and bottom sounds together, which some claim to be a thicker sound.
      Kick drums: (a) Large diaphragm dynamic, large diaphragm condenser, or ribbon mic at the hole, 4 to 18 inches from the front head, produces good lows, but with bleed from cymbals and snare drum. (b) Large diaphragm dynamic, large diaphragm condenser, or ribbon mic at the hole, just inside of the front head, produces a punchy, more natural sound, with less bleed, but fewer lows. (c) Two dynamic mics, one just inside and one outside the head, blended for the best sound. (d) Create a tunnel of sound-absorbing blankets from the front of the kick drum and extending three to five feet away from it and placing the mic inside the tunnel, which isolates it from the rest of the kit. (e) Tubular kick mic - tightly gaff tape a 24-inch-diameter PVC pipe to the front of the kick drum and use a large-diaphragm condenser mic (typically a Neumann U 47 FET) at the other end plus a large diaphragm dynamic mic just inside of the front head, each recorded to a separate track and blended for the best sound.

drummer – a person who plays a drum or drum kit.

drum pads – an electronic device with one or more round, flat surfaces that simulate the sounds of a drum kit when struck with drumsticks and usually outputs a digital signal or MIDI command. Called pads for short.

drum pattern – a set of rhythmic drum strokes or a repeated rhythm played on a drum kit, a drum machine, and/or other percussion instruments used to establish the meter and groove for a piece of music. Drum patterns tend to characterize or define some music genres. Also called a drumbeat.

drum pattern editor – a software program that allows you created and modify drum patterns on a drum machine or MIDI device.

drum replacement – plug-in software that detects when a drum on a recording is hit and replaces or overlays the hit with a sampled drum sound. This procedure either reinforces the sound of the drum or replaces it completely.

drum room – see drum booth.

drum rudiment – one of a number of fundamental patterns that form the foundation for more extended and complex drum patterns. They are the accepted standard in the performance of the basic rhythmic patterns that comprise many of the drum patterns used in Western music. Rudiments are also used as exercises for drummers to practice and hone their technical skills. All rudiments have strict sticking patterns. Rudiments were often named after the sound they made, which accounts for some of the odd names.

drum set – see drum kit.

drum shell – the cylindrical part of a drum to which one or more drumheads are attached. The shell can be made of metal, wood, or plastic—the choice of material affects the tone of the drum.

drumstick – a thin rod about 16 inches (40 cm) long, usually made of wood, with a round or oblong tip, that is used to strike a drumhead or a percussion instrument. The tip is sometimes covered with nylon or other material. Sometimes spelled drum stick.

drum throne – the stool or seat upon which a drummer sits when playing a drum kit. Called a throne for short.

drum trigger – an electronic device attached to the drums of an acoustic drum kit that sends out a MIDI signal when the drum is struck. The signal can either trigger either a note or close a connection on an outboard processor to produces a MIDI note or a drum sound.

drum tuning key – see drum key.

dry – (1) Without signal processing or an effect, such as delay or reverberation. The opposite of wet. (2) Having no reverberation or ambience. The opposite of reverberant.

drum zones – the three areas for miking a drum kit, which are mixed together to create a drum recording. These zones are: (1) close mics, microphones placed very close to the kick, snare, toms, and high hat, (2) overheads, a pair of microphones placed a few feet above the kit, and (3) room mics, microphones placed several feet in front of the kit to capture the room sound. See also drum miking techniques.

D.S – Dal Signo. A notation used in music that instructs a musician to repeat a passage starting from the segno sign. D.S. al coda instructs the musician to go back to the sign, and when al coda or to coda is reached, to jump to the coda symbol. D.S. al fine instructs the musician to go back to the sign, and end the piece at the measure marked fine. Al segno indicates that the musician should go to the sign.

DSB – Double SideBand. See sideband.

DSB-AM – Double-SideBand Amplitude Modulation. See sideband.

DSD – Direct Stream Digital.

DSD-64 – see Direct Stream Digital.

DSD-128 – see Direct Stream Digital.

DSDIFF – Direct Stream Digital Interchange File Format. An audio file format for DSD recording, which contains metadata and uses the .dff extension. It is used for SACD. Sometimes abbreviated DSF.

DSF – DSD Stream File. See DSDIFF.

DSI – DigiSystem^® Init. The driver for Pro Tools 5 and earlier on Mac computers. Such drivers used to be called inits (short for initializations), because they loaded during boot up.

D-size – see dreadnought.

DSL – Digital Subscriber Line. A technology for sending high-speed computer data over standard copper telephone lines.

DSP – Digital Signal Processing or Digital Signal Processor.

DSP56000 – see Motorola DSP56000.

DSP accelerator – Digital Signal Processing accelerator. A microprocessor, located either on an internal card or an external piece of hardware, that accelerates the performance of a DAW by performing the operation of plug-ins, thus allowing the computer's CPU to process other demands. Also called hardware accelerator or DSP hardware.

DSP block – a processor core or part of a core that performs a specific DSP function.

DSP chip – see DSP coprocessor.

DSP coprocessor – Digital Signal Processing coprocessor. A coprocessor used with a DAW to provide dedicated digital signal processing power for running plug-ins, freeing the CPU to operate only the DAW. See also DSP accelerator, SHARC, and Motorola DSP56000. Also called a DSP chip.

DSP hardware – see DSP accelerator.

DSP server – Digital Signal Processing server. A server used only for handling digital signal processing applications. A DSP server handles processes offloaded from the host machine to conserve CPU and processing capabilities.

DSR – Digital Sales Report. See DDEX.

DST – Direct Stream Transfer.

D-sub – short for D-subminiature connector.

D-subminiature connector – a multi-pin connector originally developed by ITT Cannon that comes in a variety of sizes and pin configurations, and is used for computer and audio applications. Probably the most common version is the DB25, used for RS232 ports. Also called a D connector, D-type connector, or D-sub for short.

D-taper – see taper.

DTH – Direct-To-Home. See direct-broadcast satellite.

DTMB – Digital Terrestrial Multimedia Broadcasting. See DTV.

D-to-A – Digital to Analog. See Digital-to-Analog conversion. Also written as D/Aor D-A.

DTR – Digital Tape Recorder. Any digital recording system using magnetic recording tape. This includes DAT and DCC.

DTRS – Digital Tape Recording System.

DTS – Digital Theatre System. A series of digital surround sound formats used in both commercial movie theaters and consumer applications developed by DTS, Inc..

DTS++ – see DTS HD-Master Audio.

DTS Coherent Acoustics – a digital audio data compression method developed by DTS for use in home theaters. It is included in the LaserDisc, DVD, and Blu-ray specifications. It is a competing format to Dolby's AC-3. Formerly known as DTS Zeta Digital. Sometimes called DTS Consumer or simply DTS for short.

DTS Consumer – see DTS Coherent Acoustics.

DTS-ES – DTS Extended Surround. A version of DTS surround sound that adds a third surround channel to the left and right surround channels. There are two versions: (a) Regular DTS-ES which matrix-encodes the third surround channel into the existing left and right surround signals in a 5.1-channel source and (b) DTS-ES Discrete that adds a separate third surround channel. See also THX Surround EX.

DTS HD-Master Audio – a combined lossless and lossy audio codec developed by DTS for use on Blu-ray discs for surround sound. It is an extension of the previous DTS Coherent Acoustics codec. Although it was originally an optional audio format for Blu-ray, it has steadily become the standard Blu-ray lossless audio format. The format supports a maximum sample rate of 192-kHz at a 24-bit resolution from 2 (stereo) to 5.1 channels and a 96-kHz rate and a 24-bit resolution up to 7.1 channels. However, when played back on devices that do not support the Master Audio high-resolution extension, it downgrades to a lossy track. Previously known as DTS++.

DTS, Inc. – a company founded in 1990 as Digital Theater Systems, Inc. and headquartered in Calabasas, California, that was an innovator in the field of multichannel digital audio. It is the main competitor of Dolby Laboratories, Inc. in the theater and home theater markets. In 2008, the cinema division was divested to form DTS Digital Cinema, which was subsequently purchased by Beaufort International Group Plc in 2009, changing the name to Datasat Digital Entertainment. In 2011, the DTS cinema brand was dropped, in favor of the Datasat Digital Sound branding. DTS, Inc. continues to develope and license DTS products in the home consumer market.

DTS:X – an immersive audio format developed by DTS in 2015, that uses object-based audio, similar to Dolby Atmos. Although Dolby Atmos requires the addition of extra height channels to a 5.1 or 7.1 setup, DTS:X works with standard speaker setups. It can support up to 32 speaker locations, equivalent to an 11.2 setup. DTS:X uses Multi-Dimensional Audio (MDA), an open and licence-free platform that allows movie producers to control the placement, movement, and volume of sound objects. DTS:X also allows users to adjust the volume of voices on a soundtrack to make hard-to-hear dialog easier to understand.

DTS Zeta Digital – see DTS Consumer.

DTTB – Digital Terrestrial Television Broadcasting.

DTV – Digital TeleVision.

D-type connector – see D-subminiature connector.

DVB-T – Digital Video Broadcasting-Terrestrial. See DTV.

dual banana plug – a type of banana plug with two plugs held together with a plastic yoke and spaced ¾" apart, the typical distance between binding posts on speakers. This format is designed to simplify speaker installation.

dual capstan – a type of tape machine that has one capstan before and another after the head assembly. This design provides smoother tape motion and minimizes the effects due to tension by supply and take-up reels. Also called a closed-loop drive.

dual-concentric loudspeaker – see coaxial loudspeaker.

DualDisc – a double-sided optical disc introduced in 2004 that has a non-Red Book-standard audio layer similar to a compact disc on one side and a DVD layer on the other. This configuration allows for the distribution of audio in both 16-bit/44.1 kHz (regular CD) and high-resolution [24-bit/96 kHz or 192 kHz] (DVD-A) formats and possibly including surround-sound versions, in addition to video. To date, the format has not had much acceptance.

dual-layer DVD – a DVD having two layers of data, one above the other with the top one being semi-transparent so that both can be read from the same side. A dual-layer disc can hold almost twice as much data as a single-layer disc (about 4 hours of video), which means long movies can use higher data rates to provide better quality video on a single disc.

dual mono – pertaining to a two-channel device in which each channel is separate and unrelated to the other, as opposed to stereo where the two channels are related and are usually routed together. For example, with a dual-mono preamp, you can have a vocal in one channel and an electric guitar in the other, each with its own settings and routed to different destinations.

dual-stage – see auto-release.

dub – (1) To copy a recording. (2) A copy of a recording. (3) The process of adding dialog in sync with a movie soundtrack after the movie has been completed. Also called automatic dialog replacement or ADR. (4) To re-record sound effects, ambient sounds, music, dialog, or Foley effects for a film or video. (5) To mix together onto a single track all of the separate edited tracks for a film or video production.

dubber – a machine used to playback the sound for a movie or video.

dubbing – (1) Another term for re-recording. (2) Slang for automatic dialog replacement.

dubbing mixer – see re-recording engineer.

dubbing stage – see dub stage.

dubbing theater – see dub stage.

dub stage – a special studio where music is added to the dialog and sound effects for the final soundtrack of a movie or video. It consists of a small movie theater, with a large screen, full surround sound system, a large mixing console in the place of a row of seats, and an sound-isolated machine room that houses dubbers and projectors. The DME stems can be mixed together in sync with film being projected on the screen. The theater is designed with acoustics similar to a public movie theater. Also called a mixing studio, re-recording studio, re-recording stage, dubbing stage, or dubbing theater.

duct silencer – see silencer.

dull – see dark.

ducker – a circuit design that uses ducking to automatically reduces the background sound when an announcer speaks. It is found on some PAs and paging systems, and at radio stations.

ducking – an effect that lowers the level of an audio signal to accomodate dialog, a solo instrument, or other sounds. This effect can be automated using a signal processor through the use of side-chain compression.

dummy head technique – see sphere microphone technique.

dummy load – see load, definition #2.

dump edit – see edit switch.

Duophonic – a trade name used by Capitol Records for a sound process in which monophonic recordings were reprocessed into “fake stereo.” The process consisted of splitting the monophonic signal into two channels, delaying one channel by a few milliseconds, reducing the bass frequencies in one channel, and cutting the high frequencies in the other. The result was a simulated stereo effect, but without any directional characteristics of true stereo. In some cases, the effect was enhanced with reverberation and other technical tricks. The process was used when commercial stereophonic records were first introduced to produce simulated stereo records from existing monophonic recordings to satisfy the demand for stereo records, as well as to be able to charge a higher price. In most cases, the simulated stereo recordings sounded nothing like stereo recordings and were usually not as good as the mono versions.

duple meter – a musical meter or time signature having a primary division of 2 beats to the bar, such as 2/2, 2/4, and 6/8.

duplet – a pair of equal music notes to be performed in the time of three. See also triplet and tuplet.

duplication – (1) The process of making a copy of a compact disc using a recordable CD such as a CD-R. Duplicators use machines that duplicate anywhere from 10 to 100 or more CDs at a time by loading multiple CD-Rs into a machine and copying the master. This process is used for small quantities, typically less than 300 copies. For larger quantities, replication is used. (2) The process of making multiple copies of a cassette.

duplicator – (1) A device used to copy data or music onto blank CD-R discs. These units can be as simple as two drives that require manual loading and loading to towers containing a dozen or more drives. Automatic units can hold hundreds of blank discs that can run for hours between loading and can print color labels directly on the disc. An automated unit is sometimes called a CD publisher. Some machines also can duplicate DVD and Blu-ray discs. (2) A device used to copy music from a master tape to multiple blank cassettes. (3) A company that manufactures compact discs, DVDs, and/or Blu-ray discs using the process of duplication.

dust cap – the dome-shaped object over the central hole of most loudspeaker cones. (See diagram.) Its purpose is to protects the inner mechanisms, such as the voice coil and the pole pieces, from being contaminated by dust. With some loudspeaker designs, the dust cap can be part of the acoustic design of the driver acting to enhance or suppress some the radiation of some frequencies. In some digitizingtweeter designs, the the entire sound-radiating surface is the dust cap. (See diagram.) Also called a dust dome or dome.

dust dome – see dust cap.

DUT – Device Under Test.

DV – Digital Video. A format introduce in 1995 for digitizing and storing video, primarily for use in digital video camcorders. These systems used digital video cassette as the recording medium.

DVB – Digital Video Broadcasting. A set of open standards for the broadcasting of digital television. The standards are maintained by the DVB Project, an international industry consortium. They are published by a Joint Technical Committee of the European Telecommunications Standards Institute (ETSI), European Committee for Electrotechnical Standardization (CENELEC), and the European Broadcasting Union (EBU). DVB systems include satellite television (DVB-S, DVB-S2, DVB-SH, and DVB-SMATV), cable television (DVB-C and DVB-C2), terrestrial television (DVB-T, DVB-T2, and DVB-H), handheld devices (DVB-H), and microwave television (DVB-MT, DVB-MC, and DVB-MS).

DVB-C – Digital Video Broadcasting - Cable. See DVB.

DVB-C2 – Digital Video Broadcasting - Cable - Second Generation. See DVB.

DVB-H – Digital Video Broadcasting - Handheld. See DVB.

DVB-S – Digital Video Broadcasting - Satellite. See DVB.

DVB-MT – Digital Video Broadcasting - Microwave Terrestrial. See DVB.

DVB-MC – Digital Video Broadcasting - Microwave Cable. See DVB.

DVB-MS – Digital Video Broadcasting - Microwave Satellite . See DVB.

DVB-S2 – Digital Video Broadcasting - Satellite - Second Generation. See DVB.

DVB-SH – Digital Video Broadcasting - Satellite services to Handhelds. See DVB.

DVB-SMATV – Digital Video Broadcasting - Single Master Antenna Television (or Satellite Master Antenna Television). See DVB.

DVB-T – Digital Video Broadcasting - Terrestrial. See DVB.

DVB-T2 – Digital Video Broadcasting - Terrestrial - Second Generation. See DVB.

DVC – Digital Video Cassette. The cassette containing magnetic recording tape used for recording digital video (DV). DVCs come in four different sizes, all of which contain tape that is ¼ inch (6.35 mm) wide. Small cassettes (S-size or Mini DV cassettes) are intended for amateur use, but often are used by professionals. Medium (M-size) cassettes are often called DVCPRO tapes and are for use in professional Panasonic equipment. Large (L-size) cassettes are often called DVCAM tapes and are used in standalone DV tape recorders and many shoulder-mount camcorders. Extra-large (XL-size) cassettes are sometimes called DVCPRO XL and are for use in some Panasonic equipment.

DVCAM – see DVC.

DVCPRO – see DVC.

DVD – Originally stood for Digital Video Disc and then Digital Versatile Disc, but now officially stands for nothing. An optical disc the size of a compact disc, with more than 6 times the storage capacity of a CD, that can be used to store video, audio, and data. Once called an hdCD in Europe. Just as CD specification are enumerated in books by color, DVD specifications are provided in books labeled A through E:

Book	DVD Specification
A	DVD-Video, DVD-A (Audio Only) DVD-AV (Audio & Video+ Subset of DVD-V)
B	DVD-Data
C	DVD-Audio
D	DVD-R
E	DVD-RAM
Subsets: V	DVD-Video
VAN	DVD-VAN (video; audio enabled)
5	Single-layer DVD (4.7 GB)
9	Dual-layer low-density (8.5 GB)
18	Dual-layer high-density (17 GB)

DVD-A – abbreviation for DVD-Audio.

DVD-Audio – an optical disc for delivering digital audio on a DVD introduced in 2000. Providing surround sound and longer playing time than a CD, it or its competing format SACD were intended to be the successor to the compact disc, but neither has made a significant impact on the consumer market. It is sometimes abbreviated DVD-A.

DVD authoring – the process of making a DVD video that can be played on a DVD player. DVD authoring is the final step in the process of recording a recordable DVD or the last step before the process of manufacturing (replicating) mass-produce DVDs. During authoring, menus are created, chapter points are inserted, and various other options and data are added.

DVD drive – see DVD player.

DVD duplicator – see CD duplicator.

DVD player – (1) Software designed to play DVD discs. (2) An electronic device designed to play DVD discs. Most players can also play music CDs, as well as both read-only DVD+R and DVD-R and rewritable DVD+RW and DVD-RW, although some older players may play either the plus or the minus group. DVD players may also read and write DVD-RAM discs, but they are not alway compatible between brands. A DVD drive can also play such discs, but a DVD player is typically used with a TV or home theater, whereas a drive is a peripheral device for use with a computer.

DVD-R – a recordable DVD with a capacity of 4.7 GB that can only be written once. A DVD-R uses a different and somewhat incompatible format from a DVD+R

DVD+R – a recordable DVD with a capacity of 4.7 GB that can only be written once. A DVD+R uses a different and somewhat incompatible format from a DVD-R

DVD-RAM – a rewritable DVD with a capacity of 2.6 GB, that can recorded and erased and re-recorded.

DVD-ROM – a read-only DVD that is used for use with games or computer software.

DVD-RW – a rewritable DVD with a capacity of 4.7 GB, that can recorded and erased and re-recorded. There is also a DVD+RW, but it is a non-sanctioned format.

DVD+RW – see CD-RW.

DVD subcode – see subcode.

DVI – (1) Digital Visual Interface. A specification created by the Digital Display Working Group (DDWG) for converting analog video signals into digital signals so both analog and digital monitors could handle the input. (2) Digital Video Interactive. A mostly obsolete codec developed by RCA, Intel, and GTE for storing digital graphics, audio, and full-motion video on a CD-ROM.

DWDM – Dense Wavelength-Division Multiplexing. See wavelength-division multiplexing.

D-weighting – a method for measuring sound using an equalization curve that was designed specifically for use in measuring high-level aircraft noise in accordance with standard IEC 537. The large peak in the D-weighting curve does not come from equal-loudness contours, but occurs because the humans ear hears random noise differently from pure tones, which is especially pronounced around 6 kHz. Also called D-filter or D-curve. See also A-weighting, B-weighting, C-weighting, K-weighting, and Z-weighting.

DX – see DirectX plug-in.

DXi – see DirectX plug-in.

dyad – a set of two musical notes or pitches. Although, a chord has three or more notes, in some cases a dyad can be considered to be a chord or a chord substitute, particularly for a guitarist.

Dynaco – a manufacturer of affordable, high quality audio kits, found in 1954 in Philadelphia, Pennsylvania, by David Hafler and Ed Laurent. Dynaco became a wholly owned subsidiary of Tyco, Inc. in 1969. In 1991, the Pan Orient Corporation (now Panor) purchased the right to the Dynaco trademark.

dynamic – a descriptive term for a punchy sound that produces an impression of a wide of dynamic range, related to both fast response and contrasts in volume.

Dynamic Adaptive Streaming over HTTP (DASH) – an adaptive media-streaming technique technique that enables high quality streaming of media content over the internet using conventional HTTP web servers. Similar to Apple's HTTP Live Streaming (HLS), DASH works by breaking the content into a sequence of small file segments, each containing a short interval of playback time of content that can be many hours in duration, such as a movie or the live broadcast of a sporting event. Alternative segments are encoded at different bit rates so that while the content is being played back, the client automatically selects the best alternative bit rate for the next segment to download and play back based on current network conditions. The client selects the segment with the highest possible bit rate that will not cause stalls or buffering during playback. This allows DASH to seamlessly adapt to changing network conditions, and provide high quality play back with minimal playback glitches. Unlike HLS, HDS, and Smooth Streaming, DASH is codec-independent. Also known as MPEG-DASH.

dynamic amplification factor (Q) – the mechanical gain of a vibrating object when it is excited at its resonant frequency. The amplification factor is a function of the system damping. When the damping ratio (ζ) equals zero (no damping), the amplification factor is infinite. When ζ = 1 (critically damped), there is no amplification. Sometimes called simply amplification factor, which should not be confused with amplifier gain.

dynamic cartridge – a type of magnetic phonograph cartridge.

dynamic effects – those effects that affect the gain of an audio signal, such as dynamic range compression, expansion, and gates. The other two categories of are time-domain effects, which change time characteristics of an audio signal, and spectral effects, which affect the frequency.

dynamic equalization – a type of signal processing in which the frequency varies with the signal level. A dynamic equalizer allows for adjustment of the frequency, gain, and bandwidth the same as with a conventional equalizer, but also has additional controls like those of a compressor, such as threshold, attack, and release. This combination allows the equalizer to boost or cut frequencies dynamically and more musically than with a conventional equalizer. British spelling dynamic equalisation.

dynamic filter – (1) An early type of single-ended noise reduction system that used filters with cutoff frequencies that were controlled by the signal level. During soft passages as the high-frequency signal level decreases, the high-frequency response was reduced. When the signal level was high, the full spectrum was restored. (2) A circuit used in aural exciters where a side-chain signal is used to modify the original both additively and subtractively to create the impression of an increase in both bass and high frequencies, while the mid-range sounds more focused. Such spectral shaping is designed to be related to the way the human hearing system changes at different listening levels.

dynamic headphones – headphones in which an audio signal is sent through a coil of ultra-thin wire, creating a magnetic field that moves a magnet attached to a diaphragm, causing rapid vibrations that produce sound. It is similar in operation to a dynamic microphone. Also called moving-coil headphones. See also electrostatic headphones and planar magnetic headphones.

dynamic headroom – the ability of a power amplifier to surpass its rated output for a short burst without distorting.

dynamic host processing – a process found in some DAWs in which plug-ins only use CPU power when they are active in a track or a track has audio upon which the plugin can operate. The CPU power can then be diverted to other uses during such situations making the DAW more efficient. Also called dynamic plugin processing.

dynamic loudspeaker – see moving-coil loudspeaker.

dynamic microphone – a microphone that does not require a power source. There are two basic varieties of dynamic mics: (a) the moving coil microphone, usually referred to as a dynamic microphone and (b) the ribbon microphone. Each converts sound into an electric signal by causing a conductor to vibrate within a magnetic field. The dynamic microphone uses a moving coil and the ribbon microphone uses a thin ribbon for the conductor.

Dynamic Noise Reduction (DNR) – a noise reduction system that was similar those designed by Dolby, but was not as effective.

dynamic plug-in processing – see dynamic host processing.

dynamic panning – see panning.

dynamic processing – can refer to dynamic plug-in processing (dynamic plug-in processing) or less correctly to dynamics processing.

dynamic range – (1) The range in volume from the quietest to the loudest in a program. Also called dynamics. (2) The difference between the maximum operating level and the level of the background noise (noise floor), usually expressed in decibels (dB). Dynamic range = signal-to-noise ratio (S/N) + headroom. The theoretical dynamic range for a digital audio signal depends on the bit depths, as shown in the table below:

Bit Depth	Dymanic Range (dB)	Typical Distortion
8	48.16	0.5%
12	72.25	0.1%
16	96.33	0.002%
24	144.49	N/A
32	192.66	N/A

dynamic range compression (DRC) – the reduction in dynamic range of an audio signal caused by a compressor. Also called audio compression, level compression, or simply compression.

dynamics – (1) The same as dynamic range. (2) The playing of instruments or singing loudly or softly at different places as indicated in a piece of music.

dynamic speaker – see moving-coil loudspeaker.

dynamics processing – a category of effects processing that changes the level of the audio signal (dynamics), such as compressors, expanders, limiters, and gates. See also dynamic effects.

dynamics processor – a category of effects processors that changes the level of the audio signal (dynamics), such as compressors, expanders, limiters, and gates.

Dynaquad – see ambience extraction.

dyne – a unit of force in the CGS system that when acting on a mass of one gram, increases its velocity by one centimeter per second every second along the direction that it acts. One dyne is equal to 10 micronewtons.

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Note: We believe this is the largest dictionary (glossary) of terms specific to usage within the recording industry that is currently available on the internet, with more than 8,800 entries, nearly 800 illustrations, and dozens of tables. Some of the terms have different or additional meanings in other situations, especially within the electronic, automotive, scientific, and computer industries. Of necessity there are obvious overlaps into other fields such as music, electronics, and computers, but such excursions are limited to information deemed pertinent to the knowledge required to operate and/or participate effectively in the workings of a recording studio. Also included are terms related to sound reinforcement (live performances) including wireless microphone technology because a working knowledge of that terminology is necessary for recording at live performance venues. Because recording studios also record audio for video and motion pictures (films), some terminology from those fields is included. Some scientific terms are included because they help explain studio terminology. For example, electromagnetism explains how microphones, loudspeakers, and guitar pickups work. Knowledge of radio waves and the radio frequency spectrum is needed to explain wireless devices. Any trademarks or trade names mentioned belong to their respective owners. The information contained in this dictionary is believed to be accurate at the time of publication. This information is subject to change without notice. The information was obtained from and cross-checked with a variety of sources that are believed to be reliable. However, Los Senderos Studio, LLC does not guarantee the accuracy or completeness of the information contained herein. Please contact us to report any errors, omissions, discrepancies, or broken links. Los Senderos Studio shall not be responsible for any consequences or damages arising out of the use of this information. Nothing in this glossary should be interpreted as legal advice. For a glossary providing information on legal and business matters for musicians, we suggest you consult Musicians Business Dictionary.

A note on alphabetical order: The terms in this glossary are alphabetical without regard to spaces and punctuation. For example, AM Radio follows amplitude. While this may seem to be at odds with other conventions, it eliminates confusion with words such as pickup, which is sometimes written as pick up or pick-up. In addition, all symbols such as &, -, or / are ignored. The entries on the number page (0-9) are listed in increasing value within each digit. For example, all of the entries beginning with 1 are listed before those starting with 2. For Greek letters (α-ω), the entries are in Greek alphabetical order.