ear buds – earphones with very small drivers housed in a small enclosures that fit over the ear canal (over-ear buds) or that slide into the ear canal (in-ear buds). Those that go in the canal help block out external sounds while those over the ear do not. Ear buds are notorious for producing poor sound quality, although some very expensive models are quite good. Sometimes spelled earbuds.
ear fatigue – a condition that occurs after extended time listening or working with audio, particularly at high levels. While this condition is not clinically recognized as a malady, audio professionals are keenly aware of its effects. It causes listeners to hear sounds differently than when using fresh ears. Also called listening fatigue.
early decay time (EDT) – the time that it takes for a audio signal to decay by 10 dB, based on a straight-line curve fit between the 0 dB and -10 dB points on the Schroeder curve, usually extrapolated to 60 dB of decay to be consistent with RT60. See reverberation time.
early, early sound (EES) – structure-borne sound that reaches a microphone before air-borne sound because sound travels faster through denser materials.
early reflections – the first reflected sound waves to reach a listener, variously defined as those arriving 20 to 50 ms or less after the direct sound. It includes the initial reflection, but does not include the late reflections. Early reflections bounce off of one or two surfaces and consist mostly of mid and high frequencies. When a reflection arrives in less than 50 ms, the ear does not perceive it as an echo, but it reduces the clarity of the sound and degrades stereo imaging.
ear training – a skill in which musicians, engineers, and other audio professionals learn to hear and identify basic elements of music, such as pitches, frequencies, intervals, chords, rhythms, and other characteristics. Sometimes called aural skills.
EASI – Enhanced Audio Streaming Interface. A communications standard developed by Emagic designed to standardize communications between software and hardware in professional audio applications.
Eastman Kodak Company – an American company founded by George Eastman in 1888 as a maker of photographic film. Headquartered in Rochester, New York, the company today is focused on imaging solutions and services for businesses. It provides packaging, printing, graphic communications, commercial films, and professional services. It is called Kodak for short.
E-Bow – a hand-held device that produces a magnetic field and when held over a string of an electric guitar produces a sound without plucking it, creating the effect of bowing the guitar string. The name comes from energy bow or electronic bow. Sometimes spelled EBow.
EBU – European Broadcasting Union. An international professional society created in 1950 to solve technical and legal problems among the European broadcast community. It also establishes technical standards.
EBU Mode meter – in order to standardize meters that comply with ITU BS.1770, the European Broadcasting Union (EBU) in 2010 published EBU Tech 3341, a meter specification that provides for the EBU Mode. It specifies a meter that measures momentary loudness (measured over a 400 ms period), short-term loudness (measured over the last 3 seconds), and integrated loudness (which measures a program from start to stop), as well as a set of audio signals to test the meter.
echo – (1) A reflection of a sound wave bouncing off a surface, arriving at least 50 milliseconds after the direct sound. An echo has a distinct repeat of the original sound, while a reverberation has multiple sound reflections that tend to blend together.
echo chamber – (1) A room or space with sound-reflecting walls used for producing reverberations. An echo chamber typically has a dry signal sent to a loudspeaker with the resulting reverberations being picked up by a microphone that are mixed back with the dry signal. Bill Putnam, Sr., considered the father of modern recording, is credited as the first person in the US to create an echo chamber, using a studio bathroom in 1947. Because it does not create discrete echoes, it is sometimes a reverberation chamber. It is sometimes called an acoustic echo chamber or acoustic reverberation chamber, to distinguish it from the artificial echo chamber in definition #2. (2) Any electronic device or processor that simulates the sounds created in an echo chamber. Sometimes called an artificial echo chamber or artificial reverberation chamber, to distinguish it from the acoustic echo chamber in definition #1. See also anechoic chamber.
edge yowl – sounds that occur when a loudspeaker resonates, imparting energy back into the cone, creating spurious frequencies that may or may not be harmonically related to the intended note. Also called by slang terms cone cry and ghost notes.
edgy – (1) A descriptive term for a sound that is overly punchy to the point of being uncomfortable. (2) A sound with harmonics that are too strong relative to the fundamentals, resulting in distortion or a raspy sound.
Edison effect – an effect discovered by Thomas Edison in 1883 in which certain materials heated by a filament in a vacuum will emit electrons that are attracted to an electrode with a positive potential with respect to the emitter. This effect became the basis for the invention of the vacuum tube.
Edison plug – an ordinary household electrical plug in the US, typically with two flat blades (polarized versions having one blade larger than the other) and a semi-round ground pin.
edit insertion point – (1) A point within a track on a DAW that is clicked for the purpose of making an edit. (2) The point within a track where the start, end, or synchronization point of a clip is to be placed.
E-E – Electronic to Electronic. Using the source (electronic signal) for monitoring rather than the playback head, a term more commonly used in the video industry. Audio technicians usually use the terms monitoring source or monitoring tape. Also called E to E. See also monitor selector.
effective radiated power (ERP) – the amount of power actually radiated by a combintion of a power transmitter and antenna. It is equal to the power applied by the transmitter multiplied by the efficiency of the antenna. It takes into consideration transmitter power, transmission line losses, connector insertion losses, and antenna gain, but not the height above average terrain. Also called equivalent radiated power.
effects track – (1) The audio recording of the mixdown of all the sound effects to be mixed with the dialog and music of a video or film production. (2) A track of recorded effects to be added to another track of a multitrack audio recording.
effects unit – an electronic device used to alter the sound of an audio signal. Although an effects unit can be any type of processor, the term is most often used for (a) an effects processor connected between a guitar and an amplifier that sits on the floor and is turned on and with a foot switch (often called a pedal or stomp box) or (b) a rack-mounted effects hardware unit.
efficiency (η) – the ratio of power output to power input of a device, such as an amplifier or loudspeaker, expressed as a percentage. Note: Power that is lost is converted to heat.
eight-to-fourteen modulation (EFM) – a data encoding technique used with compact discs to create a disc that is resistant to handling and storage problems, such as dust and scratches. In this technique each 8-bit block is translated into a corresponding 14-bit codeword.
ELA M250 – short for the Telefunken ELA M 250. See AKG C-12.
ELA M251 – short for the Telefunken ELA M 251. See AKG C-12.
Elco connectors – a multi-pin connector used in audio systems and other devices for connecting multi-pair cables with one connector. Elco is the US manufacture of these connectors, while Edac makes them in Canada. They are available with 20, 38, 56, 90, and 120 pins.
electret – a material that maintains a permanent charge, analogous to a permanent magnet. The name is derived from electricity + magnet.
electret condenser microphone (ECM) – a condenser microphone that uses an electret to supply polarizing voltage instead of phantom power. However, these microphones often still require phantom power to provide power for the on-board preamp. There are three major types of electret microphones: (a) Foil electret, (b) back electret, or (c) front electret. With a foil electret microphone (also called a diaphragm electret, middle electret, or classic electret), a film of electret material is used as the diaphragm itself. This is the most common type of ECM, but it also the lowest quality, because the electret material usually makes a poor diaphragm. With a back electret microphone, the electret film is the back plate of the capsule and the diaphragm is made of a suitable metalized material. With a front electret microphone, there is no back plate. The capacitor is formed by the metalized diaphragm and the inside surface of the capsule, to which the electret film is attached. Also called a prepolarized condenser microphone or electret microphone.
electrical connection – (1) A direct path between two points in a circuit between which a current can flow. It can be a wire, a connector, or other device. Often simply called a connection. (2) A point at which two devices can be connected, usually using cables and connectors.
electrical contact – a piece of electrically conductive metal that allows current to pass from one conductor to another.
electrical contact cleaner – a cleaning agent in an aerosol container used for cleaning electric contacts, connectors, and components. The cleaning agent is usually, but not always, a non-flammable solvent designed to remove oil, grease, and grime. Also called a contact cleaner or contact enhancer.
electrical recording – the method of recording introduced in 1925 in which records were recorded by sound being captured by a microphone with the electrically-amplifiedsignal being fed to a stylus that cut grooves directly in a disc. Prior to that time, the acoustic recording process had been used. This period is called the electrical era, which ended in about 1947 with the advent of the magnetic tape era. At that point, recording were made on magnetic tape before being transferred to disc.
electric charge – the physical property of an object that causes it to experience a force when close to other similarly charged objects. There are two types of electric charges: positive and negative. Sometimes called electrical charge.
electric dipole moment – a measure of the separation of positive and negative electrical charges in a system of electric charges. In other words, it is a measure of the overall polarity of the system charges. Electric dipole moment is measured in the SI units of coulomb-meter (Cm).
electric field – a field generated by electrically charged particles and time-varying magnetic fields, defined as the electric force per unit charge. The electric field radiates outward from a positive charge and inward toward a negative charge. Called an e-field for short.
electric force – the force that a charged particle exerts on another charge. Also called an electrical force.
electricity – (1) A form of energy resulting from the existence of charged particles (such as electrons or protons), either as static electricity (an accumulation of charge) or dynamic electricity as a current, that occurs naturally (such as lightning) or is produced by a generator. (2) Electric power. (3) The science that deals with the phenomena and laws of electricity.
electric polarization – a slight shift in opposite directions of the positive and negative charge within an insulator or dielectric induced by an external electric field. One of the measures of polarization is electric dipole moment, which equals the distance between the slightly shifted centers of positive and negative charge multiplied by the amount of one of the charges. Polarization (P) is the amount of dipole moment (p) per unit volume (V) of a polarized material, P = p/V.
electroforming – a process that creates thin parts through electrodeposition. The part is formed by coating a conductive layer of liquid metal skin onto a base form that is removed after forming, with the metal coating being easily separated from the form. This is the process used in vinyl mastering. It is the opposite of electroplating.
electroluminescent panel (ELP) – a plastic sheet containing a phosphor layer that uses electroluminescence to light up when the proper voltage is applied.
electrolyte – a liquid that conducts electrical current. Chemical additives have to be added to water to make it conductive. Batteries and electrolytic capacitors often contain electrolytes.
electromagnet – a core of magnetic material, such as iron, surrounded by a coil of wire through which an electric current passes creating a magnetic field. The magnetic field goes away when the current is turned off, unlike a permanent magnet which is always magnetic without external forces.
electromechanical – relating to a device, process, or system that converts electrical energy to mechanical energy or vice versa or that combines electrical and mechanical processes. Examples include solenoids, potentiometers, relays, and piezoelectric devices that are used to control, create, or adjust electric signals. Sometimes spelled electro-mechanical.
electromotive force (EMF) – the voltage developed by any source of electrical energy such as a battery or dynamo. It is represented by the Greek letter epsilon (ε).
electronic – (1) Pertaining to or operating using a circuit with many small components, especially microchips and transistors, that control an electric current. (2) Pertaining to instruments that use electric or electronic means to produce or modify the sound. (3) Pertaining to or controlled by computers or computerized systems.
Electronic Components Association (ECA) – a trade association of manufacturers and suppliers of passive and active electronic components, component arrays and assemblies, and commercial and industrial electronic equipment and supplies. It was formerly a division of the Electronic Industries Alliance (EIA).
electronic dance music (EDM) – a group of highly percussive electronic music genres used primarily in dance-based venues, such as nightclubs. It includes trance, house, techno, breakbeat, and many more styles. Also called dance music and club music.
electronic field production (EFP) – television industryvideo production that takes place in the field, not in a formal television studio. EFP includes productions, such as sporting events, concerts, nature documentaries, and conventions like the Democratic or Republican National Conventions. EFP that focuses on news reporting is often called electronic news gathering (ENG). EFP crews can range from a single camera to an entire mobile production truck.
electronic keyboard – an electronic or digitalkeyboard instrument, which has white and black piano-style keys, a sound generator or a synthesizer capable of accepting MIDI commands and producing sounds, control keys to select tones, such as piano, organ, flute, and drum kit, effects, such as reverb, echo, or sustain, and an amplifier and a speaker. Also called a digital keyboard, portable keyboard, or home keyboard.
electronic news gathering (ENG) reporting the news using electronicaudio and video devices, originally small, mobile devices such as small video cameras used to record the scene at a news event. The term came to be used by the broadcast news industry in the 1980s when such devices first started being used. Electronic news gathering now includes everything from an individual reporter with a small audio recorder or video camera to a large crew using a satellite truck. The FCC has reserved ten ENG video channels in each broadcast market for satellite trucks to send ENG feeds back to the broadcast station. Today many electronic journalists use smartphones and small audio recorders to record news events, which can be uploaded directly. ENG is a form of electronic field production (EFP).
electronics – (1) The science that deals with the behavior of electrons in vacuums, gases, semiconductors, and conductors. (2) The technology concerned with the development, behavior, and applications of electronic devices and circuits. (3) The circuits, wiring, and components in a device or piece of equipment.
electronic tuner – an electronic device that analyzes the frequency of the note being played by an instrument and indicates whether that frequency is sharp or flat as compared to a reference pitch, usually A440, although most electronic tuners can be set to other reference pitches. The player can then tune his or her instrument to the correct pitch.
electro-optical circuit – a circuit consisting of strips or layers of light conducting material on a substrate onto which light emitting and light sensitive electrical components are attached, designed to perform a specific function. They have no moving parts and are used in computers, compressors, limiters, gain controllers, potentiometers, and many other applications.
electroplating – a process that uses an electrical current to reduce metal ions dissolved in a liquid solution causing them to form a tight bond that plates an electrode. This is the opposite of electroforming.
electrostatic discharge (ESD) – the release of static electricity between two charged objects when they come to within close contact with one another. Some electronic devices, such as some integrated circuits and transistors, can be damaged by accidental electrostatic discharge. Precautions must be taken to protect such devices by storing them in a conductive foam and by grounding yourself or standing on special mats before handling these devices.
electrostatic force – the interaction between electrically charged particles.
electrostatic headphones – headphones that operate by placing a static (non-moving) electric charge on a very thin film that floats between two perforated metal plates. When voltage from an audio signal is applied across the plates, the charge attracts and repulses the film moving the air around it creating sound. Because the film weighs less than the air surrounding it, it produces no resonances or energy buildup that can lead to the coloration produced by dynamic headphones. It is similar in operation to a condenser microphone. Electrostatic headphones are usually more expensive than dynamic headphones and require a special amplifier that produces output in the range 100 to 1000 volts. See also planar magnetic headphones.
Electro-Voice (EV) – a manufacturer of audio equipment founded in 1927 in South Bend, Indiana. It manufactures products for the pro audio and consumer market, including microphones, amplifiers, and loudspeakers. It became a division of Telex in 1998, which was subsequently acquired by the Bosch Group in 2006.
elliptic filter – a filter with ripples in both the passband and the stopband (equiripple). The amount of ripple in each band can be independently adjustable. Elliptic filters have the fastest roll-off slope in the transition band of any filter. As the ripple in the stopband approaches zero, the filter becomes a Type I Chebyshev filter. As the ripple in the passband approaches zero, the filter becomes a Type II Chebyshev filter. As the ripple in both bands approach zero, the filter becomes a Butterworth filter. Also called a Cauer filter, after Wilhelm Cauer, or a Zolotarev filter, after Yegor Zolotarev.
elliptical stylus – a stylus with a conical tip that has two cuts made in it to make a longer vertical contact with the groove and a narrower front-to-back contact. An elliptical stylus tracks the groove more precisely than a conical stylus, which improves frequency response and phase response and lowers distortion, especially in the inner grooves of the record.
Emagic – a music software and hardware company headquartered in Rellingen, Germany, with a satellite office in Grass Valley, CA. Emagic began business in the 1980s as C-Lab. Emagic was acquired by Apple in 2002.
EMC Directive – ElectroMagnetic Compatibility Directive. A directive issued by the European Commission that requires products within the European Union (EU) to not emit undesired electromagnetic interference and to be immune to a normal level of interference.
EMI Group Limited – a British multinational music recording and publishing company, and manufacturer of electronics devices and systems, headquartered in London, England, until it was broken up in 2012. Its record labels included EMI Records, Parlophone and Capitol Records. Its music division was sold to Vivendi's Universal Music Group, and the publishing business was sold to a Sony/ATV Music Publishing. EMI stood for Electric and Musical Industries, which was formed by the merger of The Gramophone Company and Columbia Graphophone Company in 1931.
emission – the radiation of an radio frequency (RF) signal, whether intentional or not.
EMT – Elektro-Mess-Technik. A manufacturer of phonograph turntables and professional audio equipment. It was founded by Wilhelm Franz as Elektromesstechnik Wilhelm Franz K.G. in Berlin in 1938. It is probably best known in profession audio for the introduction of the EMT 140 plate reverb. In 1989, EMT was bought by Barco of Belgium becoming Barco-EMT. Their professional audio products were gradually phased out. In 2003, Barco sold the company to Walter Derrer, and it began operating as EMT Studiotechnik GmbH.
EMT 140 – a plate reverb introduced by EMT in 1957. A breakthrough in audio technology, it quickly rose in popularity, providing a lush and smooth substitute for spring reverb systems of the day. Although it weighed about 600 pound, the EMT 140 occupied much less space than an echo chamber. Universal Audio now produces a plug-in modeled after the legendary EMT 140.
E-mu SP-1200 – a drum machine and sampler released in 1987, produced by E-mu Systems, Inc. It achieved legendary status among rap and hip-hop artists during the 1980s and 1990s. Although it was intended to be used as both a drum machine and sequencer, its primary use became that of a sampler. An improvement of the SP-12, the SP-1200 omitted the preset drum sounds of the SP-12, which left room for up to 32 user samples of custom sampled and edited drum sounds. It could be used to create most of a song within one piece of portable gear, a first for the industry, which reduced studio costs and increased creative control for hip-hop artists.
E-MU Systems – a manufacturer of synthesizers, audio interfaces, and MIDI devices. Founded in 1971 as E-mu Systems, Inc., it was a pioneer in samplers, drum machines, and low-cost digital sampling music workstations. In 1993, it was acquired by Creative Technology, Ltd., who in 1998 acquired Ensoniq, another synthesizer and sampler manufacturer. It then merged E-Mu and Ensoniq.
enable – the function in some DAWs of turning on a track or plug-in, so that it is using CPU or DSP resources. The opposite of disable. Depending on the DAW this process may be referred to as activate, unmute track with CPU-saving preference selected, or unarchive.
encode – (1) To convert data, information, or instruction into a particular form, especially a form that can be read by a computer. (2) To convert a signal into a form suitable for transmission. (3) To apply a noise reduction system, such as Dolby, to a recording tape. (4) To change the format of a file or to compress the file into a smaller size. Also called to code. (5) To impart additional information onto an audio signal, such as spatial information. (6) To change the format of a file or to compress the file into a smaller size. Also called to code. The opposite of decode.
encoder – (1) A device or software application that converts the digital format of a file or data into another format. (2) A physical knob or control on a hardware or software device that sends out digital control signals as assigned by software to control various parameters, such as pan on a DAW or filters on a synthesizer. Also called a soft knob.
endless encoder – a rotary knob used to digitally control a parameter in a software or hardware device having no stopping point, but continues to turn until the user stops moving it. An endless encoder can support a very wide range of parameter values or very fine control, as there is no physical limitation to the range of the knob rotation. See also encoder.
endless loop – a length of magnetic recording tape in which the end is attached to the beginning so that it play continuously. Endless loops are used on some devices to produce effects such as echo. They are also used in tape cartridges such as 4-track, 8-track, and Fidelipac.
energy – the ability of a system to perform work. The SI unit for energy is the joule, the energy required to move an object 1 meter against a force of 1 newton. See also power.
energy-frequency-time curve (EFTC) – a three-dimensional graphical plot of acoustic response with frequency, energy, and time on the three axes. Sometimes called a waterfall curve or waterfall plot. Compare with energy-time curve (ETC).
energy-time curve (ETC) – a two-dimensional plot of energy versus time showing the energy relative to the level of the energy in the first peak following an impulse response (IR). The first spike in the ETC is the direct sound usually shown at a level of 0 dB and a time of 0 ms, followed by spikes which are reflections from various surfaces in the room. The plot is similar to a reverb time contour, except it shows spikes from individual reflections, which can aid in determining from where reflections are coming. Compare with energy-frequency-time curve (EFTC).
Enhanced CD (E-CD) – a certification mark of the RIAA for several formats that combine audio with computer data that can be used in compact disc and CD-ROM players. These multi-session formats include mixed mode CD (Yellow Book CD-ROM and Red Book CD-DA), CD-i, CD-i Ready, and CD-Extra and CD-Plus (Blue Book). Enhanced CDs can take advantage of unused space on music CDs to add extra information such as video clips, artist profiles, lyrics, interviews, animation, and promotional material. Also called Enhanced Music CD.
ensemble – (1) A group of musicians, singers, dancers, or actors who perform together. Sometimes called a band, music group, or combo. (2) A work for two or more vocalists or instrumentalists. (3) The performance of such a work.
entropy coding – a type of lossless coding used to compressdigital data by representing frequently occurring patterns with a few bits and rarely occurring patterns with many bits.
envelope – the variations that a sound exhibits over time—how it starts, continues, and disappears. Essentially it is the plot of amplitude vs time for a musical sound. This is defined by ADSR — attack, decay, sustain, release or AHDSFR. In addition, other sonic distinctions such as transients, pitch, timbre, and harmonic content may be considered part of the overall envelope making up a sound.
envelope generator – a circuit that generates a control signal to represent the envelope of the sound to be created, which is used to control the level of an oscillator, filter, modulator, or other sound source. The most common example is the ADSR generator. Also called a contour generator.
envelopment – the degree to which an audio signal is perceived as being all around the listener as in a surround sound or 3-D environment. Full envelopment means sound is coming toward the listener in every direction.
EP – Extended Play. A musical recording that contains more music than a single, but not as much as an album or LP. Originally an EP was a vinyl record typically containing four songs, but the term is now used for compact discs usually having four to six songs, as well as downloads having fewer than a full album of music.
Epson – Seiko Epson Corporation (Seiko Epuson Kabushiki-gaisha). A Japanese electronics company, headquartered in Suwa, Nagano, Japan, that manufacturers computer printers, imaging equipment, multimedia and home theatre projectors, and many other electronic devices. It is a division of the Seiko Group, known for making Seiko timepieces.
equipment rack – a cabinet that contains rails with screw holes at specified spacing to house electronic equipment, such as preamps, compressors, and equalizers. Equipment racks are measured in units called U. Also called an audio rack, effects rack, or simply rack for short.
equivalent noise level – a specification that indicates the self noise of a microphone. It is the sound pressure level that creates the same voltage as the self noise produced by the microphone. A low noise level is desirable when working with low level sounds, so the sound will not be covered up by the microphone noise. Equivalent noise levels are typically measured using the dB(A) scale, which weights the sound level according to the ear's sensitivity. Good results with this scale are consdired to be below 15 dB(A).
equivalent sound level (Leq) – the sound pressure levels (SPL) of a continuous signal over a given time interval that would produce the same energy as the fluctuating sound level that you are measuring. Sometimes called equivalent continuous noise level.
error concealment – an error protection technique that replaces missing information in a digitalaudio signal using an algorithm that estimates what the probable data should be. The data may not be identical to the original, but if done well should go unnoticed.
error correction – an error protection technique that correct data errors by using redundant data within a data block so that the corrected data is identical to the original.
Ethernet – a type of local area network developed by Xerox in the 1970s that provide a method for computers, printers, and other devices to be connected together in such a way that they can communicate with one another.
Ethernet header – a data field included at the beginning of an Ethernetpacket, which converts it into a frame for transmission. Each frame begins with an Ethernet header that has as its first two fields the destination and source MAC addresses. Sometimes called a MAC (media access control) header.
EULA – End User License Agreement. The terms and conditions associated with purchased software.
Euler's number (e) – a mathematical constant named for Leonhard Euler, used as the base of the natural logarithm. It is equal to approximately 2.71828... It is the limit of (1 + 1/n)n as n approaches infinity, an expression that come from the study of compound interest. It is also the sum of the infinite series 1 + 1/1 + 1/(1*2) + 1/(1*2*3) ... It is used in many science and engineering applications.
euphonic – having a sonically pleasant or agreeable sound, especially when the sound is inaccurate or colored.
euphonium – a conical-bore, baritone-voiced brass musical instrument smaller than a tuba and having a somewhat higher pitch and a mellower sound.
Euroblock – a type of terminal blockconnector with interlocking male and female connectors, typically used for the same type of signals as are used with balancedXLR or TRS connectors, found primarily in pro audio devices. The name is short for European style terminal block.
Europlug – a two-prong power plug used for domestic ac power in many European countries, except in the UK, Cyprus, Gibraltar, Ireland, and Malta. It was first specified in 1963 in Standard Sheet XVI of CEE Publication 7, and, therefore, is often referred to as a CEE 7/16 plug. It is also called a C5 plug.
Eurorack – a 3U high, 19-inch wide powered equipment rack designed for use with modular synthesizers available from a range of manufacturers, somewhat similar to but somewhat different from the 500 Series format.
EV – common abbreviation of Electro-Voice. Sometimes written as E-V.
evacuation tip – a pointed glass tip extending from the top or bottom of a vacuum tube, the remnants of the stem through which air is removed during manufacturing. When it is on the bottom, it is usually hidden inside the tube spigot.
event – (1) A single unit of MIDI data, such as a note being turned on or off, a program change, controller information, etc. (2) A defined portion of an audio file in some DAWs. Other DAWs refer to this as a region, segment, zone, clip, or sound bite.
event list – an alphanumerical list of MIDImessages and events, including start and end points, length, channel, and values, which can be edited as needed. Besides the event list, messages can be edited by graphic editing and in some MIDIsequencers by using a score editor.
expansion – (1) The increase in dynamic range of an audio signal caused by an expander when the signal crosses a threshold. There are two basic types of expansion: (a) downward expansion and (b) upward expansion (sometimes called dynamic expansion). Downward expansion is the most common type of expansion and is used in the typical expander processor. Downward expansion decreases the level of a signal when the signal goes below the expansion threshold. The amount of level reduction is determined by the expansion ratio. It is usually used to improve the signal-to-noise ratio of a recording. Upward expansion boosts the signal by the expansion ratio when the signal goes above the threshold. This is basically the opposite of compression. It is the method used to restore the original dynamic range of an audio signal that was compressed during transmission or recording in the process of companding. In the extreme a downward expander becomes a noise gate, in which lower signal levels are reduced significantly or completely eliminated. A ratio of 10:1 or higher can be considered a noise gate. Also called audio expansion.
expansion ratio – in downward expansion, the ratio of change in inputlevel to the change in output level that occurs when the signal goes below the expansion threshold. For example, with a downward expansion ratio of 3:1, if the level drops 1 dB below the threshold, the expander will reduce it to 3 dB below the threshold. For an upward expansion ratio of 3:1, the output level is increased by 3 dB for every 1 dB of change in input level above the threshold. Also called expansion slope or slope for short.
external clock – (1) A master clock that is separate and independent of the clocks in other devices that sends a timing signal to all slaves to maintain synchronization among the various devices. (2) A clock signal received from another device. Often abbreviated as ext clock.
extra efficiency tape – a formulation of high performance reel-to-reelrecording tape introduced in the 1980s, that used an equalization of 35 μsec rather than normal 50. It is now obsolete. Also called EE tape.
Eyring formula – a formula developed by Norris Eyring for estimating reverberation times. The formula is RT60 = k × V/(-S × ln(1 - αE) where k = k = (24 × ln 10)/C20 = 0.16 s/m or 0.049 s/ft, V is the volume of the enclosed space (in m3 or ft3), and S is the effective absorbing area (in m2 or ft2), αE is the area average random incidence energy absorption coefficient, and C20 = speed of sound at 20°C = 343 m/s or 1126 ft/s. Also called the Eyring equation. See Estimation of Reverberation Time Using a Modified Fitzroy Equation for more details. Other formulas used for estimating reverb times include the Sabine formula and Fitzroy formula. The accuracy of these formulas vary with their complexity.
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 7,800 entries, nearly 600 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. 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.