IAC – Inter Application Communication. A Mac driver that provides a means of linking timing and other information between two different programs running on the same computer, most commonly used to link MIDIsequencers with audio recording software.
iBiquity Digital Corporation – a company based in Columbia, Maryland, created by the merger of USA Digital Radio and Lucent Digital Radio, to develop and promote the HD radio system in the US and around the world.
IBOC – In-Band On-Channel digital radio. See HD radio.
ID3 tag – metadata used with the MP3audio file format that allows for the inclusion of data, such as title, artist, album, track number, and other information, that is stored within the file, but is not part of the audio data. There are two different and unrelated versions of ID3 tags: ID3v1 and ID3v2.
IDC – Insulation Displacement Connector. A type of connector that can be assembled without soldering or crimping. The wire is simply inserted into the connector using a special insertion tool. It provides for an easier and faster assembly.
ideal filter – the characteristics that a filter designer tries to achieve in a “perfect” filter. An “ideal” filter should pass all signals in the pass band, completely attenuate all signals in the stop band, have an abrupt transition between the two bands, and have uniform sensitivity to all frequencies. Obviously, such a filter does not exist in the real world.
idiophone – a classifications for musical instruments in which a resonant solid material made of wood, metal, or stone vibrates to produce the initial sound according to the Hornbostel-Sachs system of musical instrument classification. The eight basic types in this classification are concussion, friction, percussion, plucked, scraped, shaken, stamped, and stamping. The other four classifications are electrophone, membranophone, chordophone, and aerophone
IEC – International Electrotechnical Commission. An international standards organization that prepares and publishes international standards for all electrical, electronic, and related technologies, what they term “electrotechnology.”
IEC connector – a type of acpowerconnector as specified by the IEC, that provides for international use by means of power cords specific to particular countries. Also called an international power connector.
IEC curve – a standard set of equalization curve for use with tape machines at various tape speeds, developed by the IEC. In about 1948, Ampex designed an equalization curve for use with the standard professional recording tape at the time (3M's 111 recording tape). It was similar to equalization curves used by several other manufacturers of tape machines. In 1953, the Ampex equalization curve was adopted as a standard by NARTB (which became the NAB in 1958). Tape equalization curves were originally developed to reduce hiss and to compensate for the fact that magnetic tape did not have a linear response and tended to saturate at higher frequencies. The NAB equalization curve reduced high frequencies and boosted lows (in order to reduce the level of hum) during recording and did the reverse during playback (pre-emphasis and de-emphasis). These boosts and rolloffs were made with a slope of 6 dB/octave. As tape formulations improved, the NAB curve became less of a match for the new formulations, which did not saturate as easily, although hiss remained a problem. Then in the 1960s CCIR developed a new curve that worked better with the new formulations, but it omitted the low frequency pre-emphasis. The CCIR curve was defined for professional machines with tape speeds of 7.5 ips and higher. The CCIR curve became the standard in Europe for professional use, whereas the NAB curve remained the standard in the US for professional use, as well as everywhere for amateur use. The German standards organization DIN also adopted these standards with a few minor differences. Later CCIR merged with the ITU, and eventually became the ITU-R. The IEC assumed the responsibility for the equalization curve. Today the IEC curve (also called IEC characteristic or IEC equalization) and the NAB curve (also called NAB equalization) are designated as IEC 1 and IEC 2, respectively. A comparison of NAB and IEC equalization curves is shown in the table below:
Tape Speed (ips)
IEC Low fc/High fc μs(Hz)/μs(Hz)
NAB Low fc/High fc μs(Hz)/μs(Hz)
*Note: Since the IEC equalization is undefined below 7.5 ips, the NAB curve is normally used. Because there is no NAB spec for 30 ips, the IEC EQ is usually used.
IECEE – IEC System for Conformity Testing and Certification of Electrotechnical Equipment and Components or IEC System of Conformity Assessment Schemes for Electrotechnical Equipment and Components. A group within the IEC that sets standards for the certification of electrical and electronic products. The system is better known as the CB System, a multilateral agreement that provides for international certification of these products, allowing a single certification for worldwide market access. It began as the European Commission for Conformity Testing of Electrical Equipment (CEE) which merged into the IEC in 1985. CEE also established and published various standards for electrical equipment, most of which have been superseded by IEC standards.
IEEE 1394 – the original IEEE specification created in 1995 for connecting computer devices, transmitting up to 400 Mb/s. It goes by several trade names, including FireWire (Apple), iLink (Sony), and Lynx (Texas instruments).
IEEE 1394a – an updated IEEE specification providing for a number of enhancements for the original IEEE 1394, including transmission speeds of up to 800 Mb/s.
IEEE 1394b – the IEEE specification created in 2002 for FireWire 800.
IFPI – International Federation Phonographique Industrie. An international organization of companies and industry associations involved with recorded music. Based in London, its focus is on promoting recorded music and safeguarding the rights of record producers worldwide.
iLok – a copy protection scheme developed and manufactured by PACE Anti-Piracy, Inc. that uses a USB dongle and an online registration process, that allows licensed users of various applications and plug-ins to use the software on different computers without the need to acquire separate authorization for each computer.
image frequency – in a wireless receiver, a frequency other than the desired radio frequencycarrier that, if allowed to enter a receiver and mix with the local oscillator, will produce a cross-product frequency equal to the intermediate frequency (IF). If such frequencies are not filtered out before they get into the system, they can result in poor performance and intermittent interference.
image rejection ratio (IRR) – the measure of the ability of a receiver to reject image frequency signals, expressed as a ratio of the signal level of the intermediate frequency (IF) to the signal level of the image frequency in decibels (dB). Also called image frequency rejection ratio or simply image rejection.
Imation – a technology company based in Oakdale, Minnesota. It was founded in 1996, when 3M spun off its data storage business. Its products include magnetic tape, optical products, data backup systems, and audio and video products.
immersive sound – a type of 3-D sound that produces sound from all directions, including the front, back, sides, above, and below the listener. Currently, there are two competing, but incompatible technologies providing immersive sound for movie theaters: Auro-3D, Dolby Atmos, and DTS:X. Unlike traditional surround sound, immersive does not use discrete audio channels, but uses algorithms that send the sound in a particular direction, based on the speaker configuration. Sometimes called immersive audio. See also 24.1.10.
impedance matching – optimizing the outputimpedance of a device with the input impedance of the device it is feeding. Optimum does not alway mean that the impedance of the two devices are equal. In fact, the input impedance is usually much greater than the output impedance. Improper impedance matching can affect the sensitivity, frequency response, power transfer, and other parameters of the device. Examples when impedance matching is important are matching loudspeakers with power amplifiers and microphones with preamps. See also bridging.
impedance-matching transformer – a device used to connect cables and equipment with different impedances, which increases the transfer efficiency and maintains the high-frequency response in the signal.
impulse response (IR) – (1) A sound or signal such as a starter gun or snare drum hit that is recorded in an actual acoustic space and analyzed to create an algorithm used in a convolution reverb. (2) The reaction of a dynamic system in response to some external change. The impulse response describes the behaviour or reaction of the system as a function usually of time, but sometimes of some other independent variable.
INA-3 – a surround sound microphone technique developed by Günther Theile. INA is an acronym for Ideale Nieren Anordnung, German for “ideal cardioid arrangement.” The INA-3 is a technique for the three front channels only, and most commonly is used with the surround channel array of the INA-5. A cardioidmicrophone is used for the center channel placed 17.5 cm (7 in) in front of two cardioids for left and right channels, pointing outwards. The spacing between the left and right microphones is 35 cm (14 in). Distances between the front three microphones can be changed to adjust the ambient response.
INA-5 – a surround sound microphone technique, an extension of the three-channel INA-3 system developed by Günther Theile. INA is an acronym for Ideale Nieren Anordnung, German for “ideal cardioid arrangement.” The INA-5 uses five cardioidmicrophones. The center microphone is placed 17.5 cm (7 in) in front of two cardioids for left and right channels, pointing outwards. The spacing between the left and right microphones is 35 cm (14 in). Two additional rear cardioid mics are placed about 60 cm (24 inches) behind the front line, and 60 cm (24 in) apart, with an angle of 150° from the center mic. Distances between the front three microphones can be changed to adjust the ambient response. Also called ideal cardioid arrangement (ICA).
in and out – a slang term for a method of miking a kick drum, in which one microphone is placed inside the drum to capture more of the attack of the beater and a second microphone is place outside the drum to capture more of the boom sound. The two signals are mixed to achieve the desired kick drum sound.
inch – a unit of linear measure equal to 1⁄12 of a foot in the US customary units or approximately 2.54 cm.
incentive auction – the reallocation by the FCC (as directed by the US Congress) of the portion of the UHFfrequency spectrum previously used by TV stations to be used by broadbandwireless devices, such as smart phones. By way of auction, the FCC offered broadcasters an opportunity to voluntarily give up spectrum in return for a share of the auction proceeds, hence the term incentive auction. This reallocation also affects wireless microphones operating in this band. Sometimes called the 600 MHz auction because the frequencies being auctioned begin at 698 MHz (the upper end of the UHF TV band) and go down from there.
inductance (L) – the property of an electric conductor or circuit that causes a voltage to be generated by a change in the flow of current. The standard unit of inductance is the henry (H). More common units are the millihenry (1 mH = 10‑3 H) and the microhenry (1 μH =10‑6 H).
induction – the process by which an electrical conductor becomes electrified when near a charged body, by which a magnetizable body becomes magnetized when in a magnetic field, or by which a voltage is produced by a varying magnetic field. Induction is one the ways that stray interference occurs in audio signals. Also called electromagnetic induction.
inductor (L) – passive electronic component that stores energy in the form of a magnetic field. In its simplest form, an inductor consists of a wire loop or coil, and the inductance depends on the number of turns in the coil, the radius of the coil, and the type of material around which the coil is wound. See also choke.
inertance – the opposition to the flow of acoustic energy through a sound barrier, analogous to the resistance in an electric circuit. Since a dense, highly reflective barrier exhibits high inertance, the term is not necessarily related to the absorption coefficient or sabine ratings of the surface or insulating materials.
infinite baffle – a loudspeakerenclosure design in which the sound emanating from the rear of the speaker cone is completely isolated from sound emanating from the front, to eliminate the interaction of the two sounds.
infinite impulse response (IIR) filter – a digital filter that has an impulse response that never quite reaches exactly zero, but continues indefinitely. It looks back in time at a theoretical infinite number of previous samples to generate a result. However, there is no need for calculations to continue to infinity because the value levels off near zero and can be neglected past a certain point. This is in contrast to a finite impulse response (FIR) filter where a fixed number of past samples are analyzed and the impulse response become exactly zero at some finite time. IIR filters produce an output with ringing following a transient, similar to many analogfilters, making it ideal for emulating analog filter designs. An FIR filter is computationally intensive and introduces considerably more latency than an IIR filter. For a minimum-phase filter, an IIR design works well, but for a linear-phase filter, an FIR design is most commonly used.
information technology (IT) – (1) Anything related to computer technology, including hardware, software, storage, networking, the internet, and the infrastructure and processes used to create, process, store, secure, and exchange all forms of electronic data. Before 1990, recording were not very involved with IT. However, today IT has become an integral part of the process. (2) People or departments that work with computer technologies.
Information Technology Association of America (ITAA), – see TechAmerica.
infrasonic – a sound with a frequency below 20 Hz, the lower limit of normal human hearing. Sometimes incorrectly called subsonic, which refers to speeds that are less than the speed of sound. Also called low-frequency sound.
infringement – a breach, violation, or infraction of an agreement or rule, especially of a copyright or patent.
inherent noise – the residual noise produced by an audio device. Inherent noise is caused internally by thermal vibrations, random disturbances, and other variations, and externally by electrical signals and radio frequency inteference. Equipment can be designed to minimize inherent noise through shielding and other means, but it cannot be eliminated completely. Inherent noise contributes to the noise floor of an audio signal.
initial reflection – the first sound or echo in the early reflections of reverberation to reach a listener. An initial reflection is a reflection that bounces off only one surface. Early reflections are less distinct than the original sound, but tend to be more distinct than late reflections, which are more diffuse. Also called a first reflection.
inMusic Brands, Inc – a company headquartered in Cumberland, Rhode Island, that owns a family of brands of musical instruments, pro audio products, consumer electronics, and live sound products. Brands include Akai Professional, Alesis, Denon, M-Audio, Marantz Professional, Numark, Sonivox, and others.
input section – the input modules for all the channels on a console.
input sensitivity – a control on some amplifiers, mixers, and other electronic devices that allows you to adjust the sensitivity of the incoming signal to match more closely the output of the device being connected. Unlike a gain control, it only attenuates the input signal—it does not boost it. Adjusting an input sensitivity control to its maximum simply results in unity gain.
ins and outs – (1) The technique of layering a second vocaltake on top of a previous take, but only doubling certain words or phrases, typically those that need emphasis or embellishment. (2) Input/Output.
insert – (1) To punch in all the tracks being recorded in a recording session. (2) To route an audio signal to an outboard piece of equipment or a plug-in. (3) A point in a signal path where a signal can be interrupted to introduce another signal. Sometimes called an insert point.
insert cable – a cable used with an insert jack, usually having a 3-conductor TRS plug at the insert point that splits into two 2-conductor TS plugs each carrying separate signals, usually one used to send a signal to an effects unit and the other to return it. Other uses include splitting a stereo signal carried on a single TRS jack to separate left and right signals on TS plugs. Although insert cables appear similar to Y-cables, they are not the same. Y-splitters normally have three connectors with conductors carrying the same signal on all.
insert editing – editing of an audio or video recording in which a segment is replaced with a new segment. The opposite of assemble editing.
insertion loss (IL) – the loss in signal level that occurs when a device is inserted in an audio line usually expressed in decibels (dB).
instance – a single active or enabled plug-in opened in a DAW. For example, implementing a plug-in in a session is referred to as opening one instance of that plug-in, but if you instantiate it several times it is referred to as opening several instances of the same plug-in.
Institute of Electrical and Electronics Engineers (IEEE) – an organization headquartered in New York City of professionals involved in the electrical and electronics industries, that also sets standards for those industries.
Institute of High Fidelity (IHF) – was an association of companies that manufacture equipment for recording and reproducing music, voice, and other sounds, which merged with the EIA in 1979. It was formerly known as the Institute of High Fidelity Manufacturers (IHFM).
instrumental – (1) Performed on or written for one or more musical instruments. (2) Pertaining to a musical instrument. (3) Music played by one or more instruments and having no vocal. Also called instrumental music.
instrumental solo – in popular music a solo performance of the melody or a group of riffs played by an instrument, most often a guitar, during the break. In jazz, these solos were often improvised performances, although they were frequently pre-composed. In country music the solo is sometimes called a ride.
instrument amplifier – an amplifier specifically designed for amplifying signals from a particular type of instrument, such as a guitar amplifier, bass amplifier, or keyboard amplifier. Each type of amp is optimized for best performance with that particular instrument. They come in two main versions: (a) head unit with separate speaker cabinet or (b) combo amp, in which the amp and cabinet are combined. Called an instrument amp for short.
insulate – to cover, wrap, or separate with a material that prevents or reduces the transfer or leakage of heat, electricity, or sound.
insulation – (1) Material that is an insulator. (2) The process of insulating something. (3) The state of being insulated. (4) A material that impedes the transfer or propagation of sound. Also called acoustic barrier, soundproofing, acoustic insulation, noise barrier, sound barrier, or sonic barrier. (5) The jacket surrounding a wire or cable.
insulator – any material with such a low electrical conductivity that the flow of electric current through it is negligible, such as wood, rubber, and plastic. Opposite of conductor.
insurance take – after recording an acceptable take, recording one more just to be sure.
integrated loudness (I) – the average loudness as measured for the duration of an audio track or program, in accordance with ITU-R BS.1770. Also called program loudness or programme loudness (British). See also sliding loudness and momentary loudness.
Intel Corporation – an American multinational company, headquartered in Santa Clara, California, that manufactures semiconductor microchips.
intellectual property (IP) – creations of the mind. Intellectual property includes inventions, literary and artistic works, recordings, symbols, names, images, and other copyrightable works, trademarks, and trade secrets.
intelly – a combination of the words intelligent and telly, meaning a smart TV.
interaural cross correlation (IACC) – the measure of the difference between the sounds arriving at each ear of a listener facing a performance in a hall. There are several IACC coefficients. IACCA is determined for a frequency range of 100 to 8000 Hz and for a time period of about 1 second using no frequency weighting. IACCE3 is an average of values found for a time period of 80 ms at 500, 1000, and 2000 Hz. IACCL3 is an average of values found for a time period of 750 ms at 500, 1000, and 2000 Hz. The value of the coefficients range from -1 to +1, with -1 meaning the signals are identical, but completely out of phase, +1 meaning they are identical, and 0 meaning they have no correlation at all.
interface – (1) A device or system that allows one unit to work, drive, or communicate with another device. (2) To communicate between two devices. (3) Short for audio interface.
interface protocol – a set of rules and/or standards for an interface that allows devices to communicate with one another. The protocol defines the rules of syntax, semantics, synchronization, and sometimes methods for error correction. Protocols may be implemented using hardware, software, or a combination of both. The main types of interfaces encountered in the recording studio are USB, Thunderbolt, and FireWire, although Apple essentially abandoned FireWire in 2008. Sometimes called an interface standard.
interference – (1) The process in which two or more sound waves of the same frequency combine to reinforce or cancel each other, with the resulting amplitude being equal to the sum of the amplitudes of the combining waves. Sometimes called acoustic interference. (2) Hum, static, buzzes, and other noises in audio equipment caused by the equipment or cables picking up stray electromagnetic fields. See electromagnetic interference (EMI). (3) A process that competes with another in an adverse way, such as noise interfering with a sound signal. (4) Anything that disrupts a radio signal as it travels from a transmitter to a receiver, such as someone using the same or a nearby frequency, as well as interference from sources like those listed in definition #2 above.
interference resistance – a thin film of oxidation that forms on the cathode of a vacuum tube, especially when operated for long periods with no anodecurrent. This coating increases the resistance, increases noise, and reduces the amount of gain of the tube. The condition is irreversible.
interlaced video – a technique for doubling the perceived frame rate of a video display without consuming extra bandwidth. The interlaced signal contains two fields of a video frame captured at two different times, with one field being used for all odd-numbered lines on the screen and a second field being displayed on the even-numbered lines. This enhances motion perception to the viewer, and reduces flicker.
intermodulation (IM) – frequencies produced by the combinations (sums and differences) of other frequencies that creates new unwanted frequencies, usually in the gain stage prior to the mixer stage of a receiver or in any non-linear device. Note: Although frequently used interchageably, intermodulation distortion usually refers to audio signals, while intermodulation often refers to radio signals.
intermodulation distortion (IMD) – distortion caused by the sum and difference of the frequencies of two or more audio signals that creates new unwanted frequencies that are not harmonics of any of the original signals. Note: Although frequently used interchageably, intermodulation distortion usually refers to audio signals, while intermodulation often refers to radio signals.
International Association for Broadcast & Media Technology Suppliers (IABM) – a non-profit trade organization, formerly known as International Association of Broadcasting Manufacturers. IABM facilitates networking and interaction between suppliers and the broadcast and media technology industry.
International Business Machines Corporation (IBM) – a multinational technology, computer, and consulting company headquartered in Armonk, New York. IBM manufactures and markets computer hardware and software and provides consulting services in computers and other technologies. It was founded in 1911 as the Computing Tabulating Recording Company (CTR). It later merged with three other companies, Tabulating Machine Company, the International Time Recording Company, and the Computing Scale Company. It took the name International Business Machines in 1924, a name it already used in several other countries.
International MIDI Association (IMA) – the organization that developed MIDI, and became the MMA in 1985.
International Songwriting Competition (ISC) – an annual song contest open to amateur and professional songwriters in a large variety of genres from all over the world. The winners are awarded cash and prizes and the opportunity for songwriters, musicians, and performers to further their music careers, and gain recognition and exposure in the music industry.
International Standard Musical Work Code (ISWC) – a unique and permanent identifier for musical works issued in accordance with international standard ISO 15707. ISWC codes are issued in the form T-123.456.789-Z, where the separators are for ease of reading and are not required, but no other separators are allowed. The codes are issued in numerical sequence and contain no information about the author, title, country of origin, or publisher. The first ISWC was T-000.000.001-0 issued in 1995 for the song “Dancing Queen” by ABBA.
International Standard Name Identifier (ISNI) – an ISO specification for assigning a 16-digit identification number used to uniquely identify the names of performers, producers, engineers, and other creative participants in audio recordings and other media content that can be used in metadata without releasing any personal information.
International Steering Committee(ISC) – a committee set up by the RIAA, RIAJ, the IFPI to set standards for new audio recording formats.
internet – a global computer network that provides for the connection and exchange of data with computers worldwide. Commercial, educational, governmental, and other networks can all be connected using the same communications protocols. Sometimes spelled Internet.
internet protocol (IP) – the set of rules defining the format of data and how it is sent over the internet or other networks. Among other things, it uses IP addresses placed in headers to route data to the correct destination.
internet radio – broadcasting audio over the internet. Internet radio is sent to listeners as a continuous stream of audio that usually cannot be paused or replayed, in a similar fashion to that of traditional radio broadcasting (terrestrial radio). In this respect, it differs from on-demand file serving and podcasting, which involve downloading rather than streaming. Also called web radio, net radio, streaming radio, e-radio, online radio, or webcasting.
internet service provider (ISP) – a business that provides access to the internet and other related services.
Interoperable Master Format (IMF) – an international standard developed by SMPTE and DPP for the file-based interchange of multi-version, finished audio-visual works, and supports multi-language, multi-reel, subtitles/closed captions, video inserts, and after-the-fact delivery of content with supplemental packages. IMF uses a core framework that includes essence containers, audio and timed text essence formats, basic descriptive metadata, complex playlists, delivery, etc., that is supplemented by incremental applications specific to particular domains. A typical application will specify video codecs and image characteristics, and can specify additional descriptive metadata. By sharing the core framework across applications, IMF is designed adapt to evolving industry requirements while maintaining much of its commonality across implementations and practices.
interrupted foldback (IFB) – an audio system that provides on-air personalities (talent) with the regular program audio plus verbal cues from the director and his or her assistants through headphones or in-ear monitors. Also called talent cueing.
interval – the difference in pitch between two tones or musical notes. For example, the interval between two adjacent keys on a piano is a semitone. The interval between strings on a guitar is normally a fourth. Other intervals are shown in the table below. A melodic interval is the interval between two notes that are played one after the other, while a harmonic interval is the interval between two notes that are played simultaneously. See also interval number.
interval number – the number of staff positions on a music staff that an interval includes, counting both lines and spaces, and including the positions of both notes forming the interval. For example, the interval C to E is a third because the notes from C to E occupy three consecutive staff positions, including the positions of C and E.
in-the-box (ITB) – a slang term that refers to audio production in which all mixing and effects processing takes place entirely within a computer-based DAW, as opposed to out-of-the-box (OTB) in which external hardware processors are used.
in the pocket – slang used to describe a manner of playing music with a solid “groove” or “swing” having a great “feel.” It is used to describe drummers, bass players, and other musicians playing rhythm parts. It does not necessarily mean playing exactly on the beat, but rather playing with a consistent pattern that may be slightly ahead or behind the beat. For example, the kick drum may be struck on the beat and the snare slightly behind the beat. To be in the pocket, the bass player would have to be playing a similarly consistent pattern or groove.
intranet – a closed (not accessible by the public) computer network that uses internet protocols, usually located at a single site, such as a business location. It is basically, a private internet.
intrinsic noise – the noise that is inherent in the device or system itself, as opposed to noise induced by an external source. See self noise.
intro – the beginning of a song, which is sometimes unrelated to the remainder of the piece in either key or tempo. Short for introduction. The opposite of outro.
in tune – being tuned to the same reference pitch, or all instruments in a group being tuned alike. Opposite of out of tune.
inverse square law – in an open area the amplitude of a point sourcesound wave will decrease at a rate inversely propotional to the square of the distance from its source. Stated another way. every time the distance from the sound source is doubled, the sound pressure level (SPL) is reduced by 6 dB. In practice, sound rarely behaves in this theoretical manner as sounds are not usually in open spaces and do not emanate from a point source.
iPod™ – a portable digital media player containing a hard drive made by Apple Computer that can store and play music and video files. The original iPod was about the size of a deck of playing cards, with a monochrome screen, and a 5-gigabyte capacity. iPods can be now be purchased in a variety of sizes with color screens, and up to 120 GB of storage capacity, capable of playing movies, videos, and TV shows.
ips – the normal abbreviation for inches per second, although current formatting practices dictate that it should be in/s. See also tape speed.
IRCAM – Institute de Recerche et de Coordination Acoustique/Musique. An organization headquatered in Paris that organizes and provides facilities for research into music and acoustics as well as composition and performance.
IRT cross – a surround sound microphone technique used for the pickup of ambience, developed by the German-based IRT (Institut für Rundfunktechnik — Institute of Radio Technology). It consists of four cardioidmicrophones placed in a square formation, angled at 90 degrees from one another, 45 degrees off axis from the sound source, and 20 to 25 cm (8 to 10 in) apart. The outputs from these mics are routed to left, right, left surround, and right surround at an appropriate level compared to the front mic array. The main disadvantage of this approach is that it has a significant amount of direct sound. This technique resembles back-to-back near-coincident stereo pairs. Although some people have called it a double ORTF, it does not use the ORTF angle of 110 degrees and it is slightly larger.
ISB – Independent SideBand. A single-sideband mode of AM transmission used by some AM radio transmitters. While each sideband usually carries identical information, ISB modulates two different input signals with one on the upper sideband and another other on the lower sideband. This technology (also called the Kahn system) is sometimes used to broadcast AM stereo. Other uses are prohibited in the US by the FCC.
ISO – International Standards Organization. An international standards organization, founded in 1947 and headquartered in Geneva, Switzerland, that sets standards for a variety of disciplines. It is composed of representatives from 196 national standards organizations.
isobaric loudspeaker – a type of speaker design for subwoofers and bass drivers that uses a small, sealed enclosure with woofers (bass drivers) placed face-to-face and wired out of phase or one behind the other in phase. This design was develped by Harry F. Olson in the early 1950s, to improve low-end frequency response without increasing cabinet size, although at an increase in cost and weight.
isolation booth – a space, usually a small room, treated in such a manner as to reduce reverberation in a vocal recording or to provide separation in order to minimize leakage between the vocalist and other instruments. Sometimes called an iso booth for short. See also vocal booth.
isolation pad – a mat made of foam, rubber, or other sound absorbent material that is placed between the speaker and a table, desk, or stand upon which it rests to prevent vibrations from passing through. See mechanical decoupling.
isolation transformer – a transformer used to provide electric power from an alternating current (ac) power source to a device while isolating the device from the power source, usually to provide safety (protection from electric shock), to suppress electrical noise, or to isolate two circuits that should not be connected. Isolation transformers usually output the same voltage as the input, and sometimes have increased insulation between primary and secondary windings to provide additional isolation.
isolator – (1) A device that provides mechanical decoupling to reduce the transmission of physical vibrations between objects, such as an isolation pad. Also called a decoupler. (2) A mechanical switching device that, when open, provides galvanic isolation between a source and a destination in order to eliminate ground loops.
iterative quantization – a version of quantization available in some DAWs and plug-ins that adjusts rhythms toward the beat by a specified percentage rather than exactly on the beat. This procedure tightens up the music without making it sound robotic. British spelling iterative quantisation.
ITT Corporation – a global diversified manufacturing company based in the United States involved in a number of industries including electronics, flow control, security, and military defense. The company was founded in 1920 as the International Telephone & Telegraph (IT&T). It became ITT Corporation in 2006 when IT&T spun it off.
ITT Interconnect Solutions – a company formerly known as ITT Cannon that is headquartered in Santa Ana, California, and designs and manufactures connectors and connector assemblies. Now a division of ITT Corporation, it was founded in 1915 as the Cannon Company by James H. Cannon. Cannon was instrumental in developing some of the first equipment for sound films in the early years of the movie industry. In the 1930s, Cannon developed connectors for the aircraft industries. The D-subminiature connector was developed for military and aerospace applications in the 1950s. Also in the 1950s, Cannon developed a connector for use in military communications equipment called the XLR, that went on to be used in professional recording studios. The XLR is sometimes called a “Cannon connector.” In 2007, ITT Cannon changed its name to ITT Interconnect Solutions.
ITU – International Telecommunications Union. An international organization headquartered in Geneva, Switzerland, that coordinates global telecommunication networks and services. It was founded as the International Telegraph Union in 1865, but merged with CCIR and other organizations in 1932 to become the International Telecommunication Union. The ITU is divided into three sectors: radiocommunications (ITU-R), telecommunications development (ITU-D), and telecommunications standards (ITU-T).
iTunes – an application developed by Apple, Inc.. It is used to download, play, and organize digital media on computers, tablets, and smart phones. It can be used as a media player, media library, media management tool, and internet broadcaster. iTunes allows users to purchase and download music, music videos, television shows, audiobooks, podcasts, movies, and other digital content.
ITU-R BS.775 – a recommendation of the International Telecommunications Union (ITU) for speaker placement for a multi-channel surround standard for a 5.1 configuration, sometimes called a 3/2 format referring to three front speakers and two surround speakers. It recommends the front speakers be placed on the arc of a circle. When the front speakers must be placed on a straight line, such as when the center speaker cannot be placed behind the screen, it recommends that the sound be delayed so that all sound reaches the listener at the same time. For the rear surround speakers, a compromise of 110 degrees is recommened. While 90 degrees (directly on either side of the listener) produces the best ambience or envelopment, 135 degrees produces the best localization in the rear, and hence the compromise. Often shown as simply ITU-775.
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 8,300 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. 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.