A : The left-hand part of a stereo signal. Also known as L.
A&R : Artists and Repertoire. The department of a record company that selects the performing groups or artists who will be signed to the label, what songs or compositions each artist will record, and who will work with the artist in the production, arranging, and performance of the material in the production of master tapes.
A-2 See Voice of the Theater.
A-3 : Dolby laboratories low-bit-rate codec system used in its Dolby Digital format film, in both broadcast and consumer video formats.
A-4 : See Voice of the Theater.
A-7 : See Voice of the Theater.
A-chain : The part of the motion picture reproduction system in a theater that contains the sound transducer (such as an
optical analog track reader or digital sound format decoder), preamp, noise reduction and matrix decoding, where applicable. The A-chain equipment decodes the sound in preparation for the B-chain and loudspeakers.
A-DAM : Akai Digital Audio Multitrack. A format developed by Akai in 1987 for recording twelve tracks of digital audio data on a standard Video-8 cassette and which allows the synchronization of multiple decks for 24- or 36-track recording. The tape runs at four times the normal Video-8 speed and gives about 15 minutes of recording time at 44.1kHz.
A-roll : Film footage used to introduce or provide backup material for a live video broadcast.
A-track : The primary dialog track cut by the picture editor. The B-track and subsequent tracks would be used for overdubs.
A-type : See Dolby noise reduction.
A-weighting : An equalization curve first applied to sound level meters in an attempt to make their measurements
correspond better to the perceived loudness of sounds, decreasing the sensitivity of the meter to frequencies below 1kHz. An important note is that the bottom octave (32Hz) is attenuated by almost 40dB; the second octave (63Hz) by 26dB, and the third octave (125Hz) by 16dB. See B-weighting, C-weighting, equal loudness curves, SPL.
A.I.R. : Always In Record. The practice in a recording session to record virtually everything on the off-chance that something which was not formally recorded as a take will be useful.
A/B : A comparison between two recordings of the same material; pre- and post-equalization, or pre- and post-effects, or any other comparison between two similar audio devices.
A/D : See analog-to-digital converter.
A440 : See concert pitch.
AAC : Advanced Audio Coding. A flexible streaming format that supports multichannel audio including subwoofer and embedded data channels, using a variety of sample rates up to 96kHz. AAC is being developed as a successor to MPEG-2.
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Aachen Head : A binaural microphone developed by Head Acoustics.
AAF : Advanced Authoring Format. A cross platform interchange format used in the creation, editing, and distribution of media content in an all-digital environment.
AB recording : In the US, this means recording with a spaced pair. In Europe, this means recording with a coincident pair.
AB-reel : Term for a 23-minute or 2,050’ maximum reel of film specially made for theater screening. The AB-reel may originally have been made from two 1,000’ edit reels; "Projection reel 1AB" would have been originally been reel #1 and reel #2 during editing and mixing. (In the event that the total footage of the first three editing/mixing reels added up to less than 2,050’, there may be a projection reel "1ABC," but this is rare.) It is becoming more commonplace to edit films in AB reel format as the magnetic film units are gradually replaced with DAWs. AB-reels are also known as "big reels" or "2,000-foot reels." AB-reels are not the same as A/B-rolls, in which the camera negative is checker boarded into two strands, allowing for simple optical effects such as fades and dissolves to be made when making original-negative prints (see EK Negative) called interpositives. This latter process is not limited to two (A, B) rolls, but can involve as many rolls of film as desired, e.g., a camera negative cut in four strands would have a "D-roll."
ABS : Absolute time. Timecode which is the actual running/recording time in HH:MM:SS, where 00:00:00 is the head of the tape. For example, DATs use ABS timecode. See also feet/frames.
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Absorption coefficient : The ability of a material to absorb, rather than reflect, sound waves. A higher absorption coefficient means better acoustical damping. See bass trap, boundary effect, standing wave, Sabins.
AC : Alternating current. The current flows in both directions.
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AC bias : See bias.
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AC coupling : Coupling between electronic circuits that passes only time-varying signals (i.e., alternating current),
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AC-1 : A form of ADPCM (Adaptive Delta (Differential) Pulse Code Modulation). It was first used in 1985 for digital radio (sound-only) applications and since adopted for other DBS (direct broadcast satellite) services, including soundtrack-with-video, satellite communication networks, and digital cable radio systems. AC-1 has a data rate between 220 kbps and 325 kbps.
AC-2 : A transform encoding/ decoding scheme for audio compression developed by Dolby labs which uses 256-band transform coding at a data rate of 128 kbps or 192 kbps on two channels. Used in the Dolby Fax System and also DP5xx encoding.
AC-3 : A multichannel, digital, split-band, perceptual coding scheme developed by Dolby Labs. It produces a 5.1 channel format, using lossy compression. Designed to be the matrixing format for DVD and surround-sound with HDTV broadcasts. Versatile, in that parameters such as bit-rate and number of channels can be tailored to particular applications, unique in that AC-3’s data bits are distributed dynamically among the filter bands as needed by the particular frequency spectrum or dynamic nature of the program. Data rates vary from 32 kbps for a single mono channel to as high as 640 kbps for 5.1 format. See Dolby Digital.
AC-M : A newly developed codec based on a soft data compression ratio of between 2:1 and 3:1. Used in the Dolby Digital Dubber, it is designed specifically to record eight tracks of 20-bit material on removable media, including Iomega Jaz and MO drives. AC-M is said to be optimized for multiple record/replay generations. Initial tests have reported as many as 14 codec processes being possible with no audio degradation.
ACA : Active Combining Amplifier. See combining amplifier.
Academy centerline : See optical track.
Academy curve/Academy sound : The name of the standard mono optical track that has exsisted since the beginning of
sound on film. Standards were codified in 1938, although the standard has changed somewhat through the years. The standard specifies a flat response throughout the range of 100Hz-1.6 kHz and is down 7dB at 40 Hz, 10dB at 5 kHz, and 18 dB at 8 kHz. Also called an N-Curve. See also X-Curve."
Academy leader : The visual countdown that precedes the first program frame of a motion picture. Symbols and numbers on the academy leader are used for aligning the various film reels and the optical track for composite printing, for aligning the workprint and edited soundtracks for mixing, and for timing the change-over from one reel of film to another during projection. Academy leader contains one number per foot following the Picture Start, with 11, 10, etc., leader to three. (As projected, these numbers appear upside-down.) Named after the Academy of Motion Picture Arts and Sciences, which sets all film format standards. See also leader, SMPTE Universal leader, plastic leader, fill leader, LFOP.
Academy Theater : Specifically, the Samuel Goldwyn Theater at the Academy of Motion Pictures Arts and Sciences on Wilshire Boulevard in Los Angeles, considered the best-sounding theater in the world. Academy members screen films at the Academy Theater prior to voting on them for the Oscar awards.
Accelerando : An indication that the tempo of a piece of music should gradually be increased.
Accent Miking : A recording technique using a midfield mike to add more room presence. Accent pickup should sound natural and not overly present.
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acceptance angle : The usable working area in front of a microphone is defined by the polar pattern and is called the acceptance angle.
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Accidental : In a musical scale, the accidentals are the extra sharp and flat notes that are not part of the diatonic series. For example, in the key of C on the piano, the accidentals are the black keys.
Acmade : The British manufacturer of edgecoding machines.
Acoustic baffle : See baffle.
Acoustic feedback : A squealing sound when the output of an audio circuit is fed back in phase into the circuit’s input. See feedback.
Acoustic intensity : See sound pressure level.
Acoustic labyrinth : (1) A type of design for the housing of highly directional microphones that enhances the rejection of off-axis sources. Two or more concentric tubes in front of (and sometimes around) the capsule create a compact series of folded pathways through which all sounds approach the diaphragm. Those arriving on-axis reach the capsule via these paths in phase coherence. Off-axis sounds, due to the different lengths of the passways, reach the diaphragm and are partially or fully removed due to phase cancellation. (2) A type of speaker enclosure in which sound waves emanating from the rear of the woofer cone travel through a long, folded interior path before coupling with the outside. This extends bass response considerably."
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Acoustic lens : A device placed in front of a high-frequency speaker that disperses or directs the sound in a desired pattern. Normally used to increase the angle of dispersion, either horizontally, vertically, or both.
Acoustic suspension : A loudspeaker designed for, or used in, a sealed enclosure. Typically, a low-frequency loudspeaker baffle where most of the damping of the cone is the result of the elasticity of the air in the sealed cabinet.
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Acoustics : The science or study of sound and its interaction with the human hearing mechanism.
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active : (1) An audio device which requires a power source such as from an AC line or battery, as opposed to passive. Sometimes amplifying components such as transistors or ICs are called active circuit elements. (2) See MIDI patchbay.
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Active crossover : See crossover network.
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Active equalizer : An equalizer that employs active components such as transistors or ICs in its processing circuits. A pre-amplifying circuit generally follows each stage of actual equalization, boosting the signal level to restore unity gain. See also passive equalizer.
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Active monitor : A type of loudspeaker which has amplification circuitry built-in. In addition, a true active monitor system utilizes active equalization and active crossovers to precisely contour the system sound. If there is only one amplifier driving all transducers, and/or there is no active equalization or crossover circuitry, the terms powered speaker or powered monitor are preferred.
Active sensing : A MIDI system message that carries no note data or control instructions, but simply indicates to a receiving device that the MIDI line is in working order.
adagio : A slow or leisurely tempo: 66-76 bpm.
ADAT : Alesis Digital Audio Tape. A second-generation (1992) MDM. An 8-track, S-VHS-based digital audio recorder. Like the Tascam DA-88, ADAT systems record digital audio on consumer video casette formats and provide for interlocking up to 16 8-track, rack-mount recorders in sample-accurate (48kHz) sync for up to 128-track recording. ADAT is a 16-bit format, currently supported as well by Panasonic, using T-180 S-VHS tape. ADAT-II is a newly proposed 20-bit S-VHS format used by newer Alesis and Studer 8-track recorders. See also DTRS.
ADB : Apple Desktop Bus. The original serial interface for the keyboard, mouse, and other "desktop" peripherals on Apple computers. ADB has recently been replaced by USB.
ADC : See analog-to-digital converter.
Additive synthesis : The generation of complex musical waveforms in electronic synthesizers by the linear addition of sine wave components whose frequency relationship is a harmonic series. See sample synthesis, sound synthesis, subtractive synthesis.
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Address track : A control/timing track on the edge of videotape (1", C, and 3/4" formats) that contains control data for quick and accurate location of program material, recorded at the same time as the picture. See control track.
adjustable turnover : A variable tone control in a preamplifier that allows the adjustment of the boost/cut and the frequency below or above which the gain/attenuation is applied (turnover), but not the rolloff slope of the shelving equalizer. If it were possible to adjust the rolloff slope, the result would be a fully parametric tone control.
ADL : Audio Decision List. ADL is also known as AES 31. It is an edit data exchange format for audio mixing and workstation. This ASCII based design provides sample-accurate editing. It also includes file locators within a structure to support exchange between disk based audio systems The ADL or AES31 is officially titled: "AES standard for network and file transfer of audio — Audio-file transfer and exchange Part 3: Simple project interchange.”
ADPCM : Adaptive Delta (Differential) Pulse Code Modulation. A type of split-band, time-domain audio compression algorithm for 16-bit digital audio based on describing level differences between adjacent samples. Different from conventional linear PCM by coding only level differences between samples, rather than the absolute level of each sample. According to the characteristics of the audio signal, ADPCM adapts the step size represented by each quantizing interval to accommodate rapid changes in level caused by high frequencies or transients, thereby providing an overall reduction in bit rate; the compression ratio is 4:1. There are at least two ADPCM standards: Microsoft and IMA/ADPCM, the latter popular for multimedia applications. See delta modulation, split-band, sub-band, transform coding.
ADR : Automatic Dialogue Replacement. Recording of dialog for a scene after it has been shot, usually to replace location sound that is unusable because of street noise, camera noise, etc. The workprint and sync magnetic film transfer for the scene are spliced into continuous loops and projected in a sound studio so that the actors can recreate the phrasing and feeling they had on the set. New takes are recorded on a separate mag film loop and/or other synchronous tape until an acceptable performance is obtained. Also see virgin looping, looping, and lip sync.
ADSL : Asymmetric Digital Subscriber Line. A high-speed Internet connection that’s called “asymmetric” because it’s capable of much faster download speeds than upload speeds. It is faster than ISDN but cheaper than T-1.
ADSR : Attack/Decay/Sustain/Release, the four segments of a common type of sound synthesizer envelope. The controls for these four parameters determine the duration (or in the case of sustain, the height) of the segments of the envelope. Two additional parameters, D (Delay Time) and H (Hold Time) are available on some synthesizers. See envelope, envelope generator.
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ADT : Auto Double Tracking. An effect produced by taking a track and copying the material onto another track, delayed by a few ms, then mixing it with the original. Like chorusing, but with a shorter delay. See also double-tracking.
AES : Audio Engineering Society. The professional organization whose members report on new technological developments in audio, and bring together designers, manufacturers, and users of various audio equipment to establish international standards.
AES/EBU : Audio Engineering Society/European Broadcast Union. A standard for encoding multiple channels of digital audio along a serial cable, officially named AES3-1985. The standard specifiesUsually uses 3-pin XLR jacks and balanced line cables, usually running at +4dBm. Originally designed as a self-clocking system, a subsequent addendum to the specification permitted master clock systems. Two channels of digital audio data are multiplexed on a single conductor within the cable, with a maximum bit depth of 24 bits. Data are transmitted at 64 times the sample rate, allowing the possibility of sending two channels of 24-bit audio (plus ECC) to play the resulting stereo signal in real-time. AES/EBU does not carry the SCMS copy code, and is a self-clocking protocol. It has been adopted by the EIAJ, which calls it the CP-340, Type 1. See also S/PDIF.
AES/EBU null clock : See null clock.
AES31 : Standard for network and file transfer of audio: Audio-file transfer and exchange. A file format that can be converted to AAF lossless-ly. However, this file structure is not as deep as that of AAF and file transfers from AAF to AES31 are lossy.
AF : Audio Frequency. This refers to frequencies within the audible range, usually taken to be 20Hz-20kHz. This frequency range is an average; many people hear tones below 20Hz, although most people are virtually deaf above 15kHz or 16kHz. See Hz (Hertz).
AF : Alternative Frequency. See RDS.
AFM : (1) Audio Frequency Modulation. A processing scheme used for recording high-quality analog audio in videocassette recorders equipped with "Hi-fi" stereo audio.
(2) American Federation of Musicians. The union that represents professional musicians in all their client and employer relations.
After-fader listen : (AFL) On many recording and mixing consoles, there is an option labeled AFL, or after-fader listen. This allows the listener to hear the audio after the channel fader has effected the audio signal. The AFL is also known as post-fader listen. The oposite of AFL is pre-fader listen.
Aftertouch : A type of MIDI controller data, generated by pressing down on one or more keys after they have reached and are resting on the keybed. Also called pressure. See channel pressure, poly pressure.
AFTRA : American Federation of Television and Radio Artists.
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AGAC : American Guild of Authors and Composers. A third performing rights organization similar to ASCAP and BMI but much smaller. AGAC primarily represents modern classical composers.
AGC : Automatic Gain Control. See AVC.
AGP : Advanced Graphics Port. A dedicated high-speed interface between PC memory and a graphics card and monitor. Before AGP existed, graphics cards were fitted into standard PCI slots and could cause audio clicks and pops if they didn’t correctly release the PCI buss for other duties when requested, thereby preventing audio data from reaching a PCI sound card. Nowadays all PCs use AGP graphics technology, which provides faster graphics performance and avoids such audio interference problems. As an aside, music applications don’t use 3D graphics, so musicians don’t need an expensive state-of-the-art graphics card. Far more useful is a good-quality 2D dual-head model that supports two monitor screens, since most music software will let you place the song’s arrange page on one screen, and the software mixing desk on the other, which makes working with complex multi-track songs far more pleasurable.
Aharmonic : See inharmonic.
AIFF : Audio Interchange File Format. A common Macintosh audio file format. It can be mono or stereo, at sampling rates up to 48kHz. AIFF files are QuickTime-compatible and support uncompressed mono, stereo, and multichannel audio at many different resolutions and sampling rates, including the CD standard. It was designed to serve as a universal interchange format that allows any program to open a digital recording created by any other program. AIFF is high-quality audio, used in pro-level Mac and PC audio software. As AIFF is a standard for uncompressed audio, Apple introduced AIFF-C which can use MACE and IMA/ADPCM compression with ratios as high as 6:1, but the audio sound quality suffers.
AIM : Amplitude Intermodulation Distortion. Intermodulation distortion where one signal will cause amplitude modulation of another signal.
Air pressure or Velocity Mic converts sound waves traveling in air into an audio signal traveling in the mic cable.
Air suspension : An acoustic suspension loudspeaker.
Airline version : A remixed and possibly re-edited version of a film that has any objectionable material removed. The airline film standard is more stringent even than those of the broadcast networks, and is often used as a benchmark for TV viewing.
Algorithmic composition : A type of composition in which the large outlines of the piece, or the procedures to be used in generating it, are determined by the human composer while some details, such as pitches or rhythms, are created by a computer program.
Alias : A file on a Mac that serves as a pointer to another file. The most common use for an alias is to sit on a desktop or in a top-level folder, where the real document or application file is nested deep within the file system. This is similar to a shortcut file on a PC-type computer.
Aliasing : Distortion that is produced when higher harmonic components of the input audio signal sampled by a digital recording device, or generated within a digital sound source, lie above the Nyquist frequency. This happens when the sampling rate is less than twice the frequency of the signal being sampled. The effects of aliasing differ from some other types of distortion in that its pitch changes radically when the pitch of the intended sound changes. Also called foldover. See anti-aliasing filter.
alignment : (1) In tape recording, the process of adjusting all parameters of the position and orientaton of the tape heads and guides with respect to the tape path. See azimuth. (2) The adjustment or calibration of any parameter of an electronic circuit or device, e.g., program level, bias level, to bring this parameter into conformance with an industry standard. (3) The process of matching mixer and recorder meters so that only one meter needs to be watched during recording. When the mixer and (analog) recorder are both peaking about 0VU, this minimizes the noise and distortion in both units. Ideally, both units would be matched with a steady tone (the C or B two octaves above middle-C, or about
2kHz, for example.) See line-up tone.
Alignment recording : See biased noise.
All-Notes-Off : A MIDI command, recognized by some but not all synthesizers and sound modules, that causes any notes that are currently sounding to be shut off. The panic button on a synth or sequencer usually transmits All-Notes-Off messages on all 16 MIDI channels.
All-pass filter : See all-pass network.
All-pass network : An all-pass network, also called an all-pass filter, is an electrical circuit with a uniform amplitude response versus frequency response, but with a phase-shift which does not vary in a linear relationship with frequency. (A pure time-delay device such as a digital delay line will have a phase-shift which is directly proportional to frequency, i.e., its phase-shift increases at a constant rate with frequency.) Complex filters often have significant phase distortion because they are not phase linear, and an all-pass network can be designed to correct phase anomalies without affecting the amplitude response.
Alla breve : A term historically related to mediæval note lengths, in which the breve was one of the shortest notes. In modern usage, the term is usually used to denote 2/2 (cut-time). In commercial and popular music, it is frequently used to mean half-time, i.e., play twice as fast. See time signature.
Allegro : A lively to reasonably fast tempo: 116-150 bpm. Allegretto is a slightly slower tempo than allegro.
alternating current (AC) : An electrical current that periodically changes in direction. The rate of alternation is called the frequency and is measured in cycles per second, or Hertz. Audio signals are always alternating, the frequency corresponding to the pitches of the sounds the signals represent. See Appendix B.
AM suppression : The ability of an FM tuner or receiver to reject amplitude modulation of the received signal and be sensitive only to frequency modulation. Much of the interference and noise in broadcasting appears as amplitude modulation, so a tuner with good AM suppression will have less distortion and noise than a tuner with poorer suppression. Also called AM rejection.
Ambience : Ambience refers to the acoustical qualities of a listening space, such as reverberation, echoes, background noise, etc. On most music recordings, some of the ambience is recorded along with the music and are, to a certain extent, reproduced in the listening environment, e.g., an organ in a cathedral. See room tone, walla, NC Curve.
ambience track : An edited roll of magnetic film, or one track of multitrack tape, assembled by the sound editor in preparation for the final mix of a motion picture or video production, containing the series of room tones or ambient sounds of the various sets and locations in which a scene was shot.
Ambient noise : Ambient sound which is environmental in nature, such as traffic noise coming through walls, heating or air conditioning, or other extraneous sounds which cannot be turned off or removed.
Ambient sound : Sounds such as reverberation, room tone, walla and atmospherics that form a background to the main sound, usually in the context of a film soundtrack of a motion picture, taking place at any given moment. The lack of ambient sound is noticeable because the human hearing system expects it. See also ambient noise.
Ambisonics : A system for the reproduction of a three-dimensional sound field, using two or more transmission channels and four or more loudspeakers. See Soundfield microphone.
AMEI : Association of Music Electronics Industries. A group that works with MMA on MIDI standards, among other things.
amp/speaker simulator : A filter circuit that mimics the amplifier and loudspeaker voicing of an electric guitar and amplifier system.
ampere (A) : The unit of measurement for electrical current in coulombs (6.25 x 10^18 electrons) per second. There is one ampere in a circuit that has one ohm resistance when one volt is applied to the circuit. One should not speak of the "flow of current." The current exists; the charge flows. This is analogous to the current in a river, which consists of the flow of water.
AMPEX : A former manufacturer of videotape recorders, analog audio tape recorders, and associated magnetic tape media. For the historic trivia fan, AMPEX is an acronym based on the founder’s name, Alexander M. Poniatoff Excellence.
Amplifier : An electrical circuit or device designed to increase the current, voltage, or power of an applied signal. An amplifier is an active device and, strictly speaking, should always increase the power of a signal; some amplifiers, such as certain distribution amplifiers, may only reduce the impedance level of the signal for the purpose of driving long lines.
Amplifier gain : The amount of amplification that an amplifier provides is called its gain. The gain is a ratio of the input signal level to the output signal level and is simply a number. Commonly expressed in dBindB, one should not express the voltage gain of an amplifier in dBindB unless the input and output impedances are matched as the gain of a typical amplifier is not related to its power output capability. For instance, if an amplifier has a voltage gain of 10, it might be said that it has a gain of 20dB because it actually would raise the power level of a signal by 20dB if the input and output impedances were matched. In practice, however, this is very seldom the case, and the true power gain is usually very much different from what would be predicted by the voltage gain. See impedance matching.
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Amplitude : The relative strength (amount) of a signal, without regard to its frequency content. Amplitude is measured by determining the amount of fluctuation in air pressure (of a sound), voltage (of an electrical signal), or numerical data (in a digital application). When the signal is in the audio range, amplitude is perceived as loudness. Amplitude is the measurement of how much energy the sound has, i.e., the total change in air pressure during a single cycle of the sound wave. Amplitude, or sound pressure, is measured in a scale called decibels (dB). An increase of 3dB is equal to a doubling of a sound’s pressure. Amplitude can be expressed as either a negative or positive number, depending on the signals being compared. See also magnitude, SPL.
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Amplitude errors : See frequency response errors, jitter.
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Amplitude Modulation (AM) : The instantaneous amplitude modulation of one signal by another. This results in the formation of sidebands which contain the same information as the original signals, but translated upwards and downwards in frequency. In AM radio transmission, the audio signal is combined with a very high-frequency sine wave, called a carrier, in such a way that the amplitude of the carrier is varied in exact response to the amplitude and frequency of the signal. This is called the amplitude modulation of the carrier. The modulated carrier is transmitted at high power where it is received by radio sets that are tuned to the carrier frequency. The modulated carrier is then demodulated by a process called detection, recovering the original signal. In radio, a circuit that does amplitude modulation is also called a heterodyne.
Anacrusis : See beat.
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Analog : Capable of exhibiting continuous fluctuations. An audio signal is an electrical replica, or analog, of the waveform of the sound it represents. The voltage of the signal varies up and down (negatively and positively, in electrical terminology) the same way as the sound pressure varies up and down at the microphone. In an analog synthesizer, such parameters as oscillator pitch and LFO speed are typically controlled by analog control voltages rather than by digital data, and the audio signal is also an analog voltage. Compare with digital.
analog recording : Any method of recording in which the recorded waveform is a continuous representation of the original signal, e.g., conventional magnetic tape recording.
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Analog sequencer : A sequencer into which sounds for storage and playback are fed as analog signals, via analog potentiometers.
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Analog synthesis : See subtractive synthesis.
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Analog-to-digital converter : Commonly abbreviated A/D converter or just A/D. A device that changes the continuous fluctuations in voltage from an analog device (such as a microphone) into digital information that can be stored or processed in a sampler, DSP, or digital recording device.
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Anamorphic : The camera/projector lens system which squeezes an image, usually originally in a 2:1 aspect ratio) onto film during shooting and "unsqueezes" it during projection. The resulting viewed image has an aspect ratio twice as wide as what was originally recorded on the film, e.g., if the image on the print is 2.2:1, the screen image will be 2.4:1. See also CinemaScope, flat(4), ‘scope.
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Andante : At a "walking" speed: 76-94 bpm. Andantino can mean either a little faster or a little slower than andante, although it more commonly denotes a little faster.
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Anechoic : Without echo. Said of an acoustic which is free-field, and specifically of a room which is designed to produce no reverberation or other echo effects. This is achieved by giving the walls very irregular surfaces of considerable and varying depths so that, in theory, all sound waves which strike them are completely absorbed and not reflected. Anechoic chambers are used to test audio equipment and for other types of acoustic and electromagneticelectro-magnetic research.
anharmonic : See inharmonic.
Anhysteretic : See hysteresis.
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Anode : The anode in any electronic component, such as a silicon diode or a vacuum tube, is the electrode normally connected to the positive voltage.
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Answer print : The first composite print made from the edited picture negative in 35mm film, or the A- and B-rolls of a motion picture in 16mm. Each shot is exposed, color-balanced, and otherwise processed. Further changes and corrections can be made in a second or third answer print, if necessary. In many contracts, the delivery of the answer print is specified because it means that post has ended and release printing can begin, although the release print is usually made from an internegative, not the answer print. The answer print is not the same as a black-track answer print which contains no soundtrack.
Anti-aliasing filter : Before a signal is subjected to the process of A/D conversion, it must be passed through a lowpass brick-wall filter to remove any components that are higher than the Nyquist frequency. This is because it requires at least two samples per cycle to determine the existence and strength of a frequency component or the A/D process will
create aliased signals. See reconstruction filter, decimation, FIR, IIR.
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Anti-imaging filter : See reconstruction filter.
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Antinode : A place of minimum sound pressure level in a standing wave, as opposed to a node, which is a maximum level.
Antiphase : See out-of-phase, phase reversal.
Antiphonal : A term used to describe music that is played or sung in alternating sections by two separate groups of performers, widely separated.
AOR : Album-Oriented Rock or Adult Oriented Rock. A tendency of some FM radio stations to play longer album tracks.
Aperture time errors : In an A/D converter, the sample-and-hold circuit would ideally take zero time to determine the level of the signal waveform and to hold this level until the next sample is called for. However, it takes a finite time to charge the holding capacitor in the sample-and-hold circuit, and this is called the aperture time. Because the time required to establish a new value of charge depends on the amount of change in the signal level from one sample to the next, the aperture time will vary with the rate of change in signal level, increasing for high-level, high-frequency signals. The starting time of the sampling aperture is also slightly uncertain, and this is called jitter. In other words, lack of precision in the sampling time leads to amplitude errors in rapidly changing signals. The errors involve aperture time, uncertainty in aperture time, and jitter. The result is a distortion of the sampled signal which rises with frequency.
Apple menu : The main menu on a Mac, used to access system utilities (such as Keycaps), applications, files, and control panels. This is the equivalent of the Start menu on a PC-type system.
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AppleScript : A system-wide macro facility on Macs which gives operating system-level control for compatible applications.
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APPV : Audio Post-Production for Video. The process of preparing the individual soundtracks and the final mix for a videotaped production.
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APRS : Association of Professional Recording Studios. An industry body set up to ensure a uniform standard of service and practice in the area of sound recording.
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APRS Tape-Label System : The APRS has decided on a standard color-code for tape labelling:
APT x100 : See ISDN.
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Aria : Italian for air (song). Generally indicates a composition for solo voice with accompaniment, also by extension, a lyrical instrumental piece.
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Arpeggio : The playing of chord patterns by sounding each note in a sequence, rather than simultaneously. An arpeggiator is a device which will automatically produce arpeggiation, given the parameters which control Direction (up or down or random), a Hold button which allows note patterns to be triggered which keep playing when the keys are released, and a Range control which sets the group of notes to be played over.
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Arrangement : (1) A version of a piece of music for resources other than those originally intended. This may be an instrumental version of a vocal number, a piano reduction of an orchestral piece, or may involve altering other parameters of the original, such as its harmony, rhythm, or structure. (2) In sequencers, a term sometimes used for the general layout of tracks, channels and patches, rather than a complete song. This template can often be saved as a separate file.
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Articulation : The way of characterizing notes (usually in a melody) by the precise control of their individual lengths to produce or eliminate gaps between them. The terms staccato and legato reflect the two extremes of articulation. It is one of the most important ways by which music can be shaped into phrases.
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ASCAP : American Society of Composers, Authors, and Publishers. The first performing-rights organization formed in 1908, ASCAP collects fees for broadcast of recorded compositions on radio and television, and for live public performances of music and distributes payments to the copyright holders of these compositions.
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ASCII : American Standard Code for Information Interchange. The most common encoding for transmitting text data digitally. The code employs 8-bit binary words, by which each letter of the English language, numeral, and symbol is uniquely designated.
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ASIO : Audio Stream Input/Output. Steinberg’s protocol for communication between audio hardware and software. Used in Cubase. It bypasses the operating system’s standard multimedia audio drivers to provide multi-channel support, improve audio timing, and reduce monitoring latency. ASIO runs at a lower level (it bypasses much of the Windows OS) and typically manages lower latencies than both MME and DirectSound.
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Aspect ratio : The width-to-height ratio of an image. Specifically in film, the format that the film image is intended to be shown in, most commonly expressed as width relative to height, where the height parameter has been scaled to represent 1 unit. Standard TV screens are 1.33:1, films shown in U.S. theatres are 1.85:1, anamorphic films are 2.4:1. Ratios may also be expressed as integers, e.g., the TV ratio may be expressed as 4x3, and widescreen TVs are 16x9, or an aspect ratio of 1.78:1.
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Asperity : A small irregularity or imperfection in the surface of a magnetic tape. Low-frequency noise in analog tape recordings caused by asperities produce asperity noise in the recording, a type of modulation noise in that the noise is manifested in the band immediately above or below the program signal. See calendering, dropout.
assemble editing : Editing of an audio or video program by making a master copy of the various takes, rather than physically splicing pieces of tape together. Virtually all digital editing is done this way. The opposite of insert editing.
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Assembly : See copyediting.
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Assigns : Push-buttons on the input modules of a control console that connect, or assign, that particular input to any of the output busses of the console. The signal is routed to the desired tape track of the destination device usually by a matrix of switches in each module of the mixing and/or recording console. This routing process is known as assignment.
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Asynchronous : Not according to a fixed rate of repetition. An asynchronous signal can occur at intervals which do not necessarily coincide with a fixed-rate system or master clock pulse.
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ATA : See IDE.
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ATF : Automatic Track Following. The system used by R-DAT players to ensure that the rotary heads follow the recorded track. This uses a set of signals that is recorded along with the digital data and which are passed to the servo controls to ensure that the tape is correctly positioned with respect to the heads.
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ATM : Asynchronous Transfer Mode. A high-speed cell-switching transport standard favored by WAN architects. Used as a LAN networking solution. ATM is capable of getting the job done, but inability to guarantee delivery, tiny fixed frame length and sizeable transmission overhead mean that it is best used for enterprise backbones and WANs.
Atmospherics : See backgrounds.
ATR : Audio Tape Recorder. This is the analog version. A digital audio tape recorder is called a DTR.
ATRAC : Adaptive TRansform Acoustic Coding. A lossy, 5:1-formatsplit-band perceptual coding and compression scheme for reducing data to be written on a MiniDisc. ATRAC offers a 5:1 data reduction ratio in the case of MiniDisc, employing the equivalent of 52 filter bands for spectral analysis and requantization. Later versions of ATRAC vary the size of the sample blocks dynamically between 11.6ms and 1.45ms according to the input signal to allow for temporal masking, providing extremely good resulting sound.
Attack : The first part of the sound of a note. In a synthesizer envelope, the attack segment is the segment during which the envelope rises from its initial value (usually zero) to the attack (peak) level (often the maximum level for the envelope) at a rate determined by the attack time parameter. See ADSR.
Attack time : (1) The rate of attack of a note. (2) The time it takes for a compressor or limiter to reduce its gain after a strong signal is applied to it. See release time.
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Attack transient : The actual attack waveform. See transient.
Attenuation : The reduction, typically by some controlled amount, of an electrical signal.
Attenuator : A potentiometer (pot or pad) that is used to adjust the amplitude of the signal passing through it. The amplitude can usually be set to any value between full (no attenuation) and zero (infinite attenuation). Pots can be either rotary or linear (sliders), may have discrete dentents (more often in older equipment), and can be either hardware or virtual sliders on a computer screen.
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AU (.AU) : An audio file format developed by Sun Microsystems, supported by some PC and Mac audio programs. This format supports stereo and mono files with either 8-bit or 16-bit resolution. It can encode linear files, or use µLaw or ADPCM compression.
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Audio : "I hear" in Latin. The term pertains to any signal, sound, waveform, etc., that can be heard, as opposed to subsonic or ultrasonic sound, radio-frequency signals or video signals.
Audio Blank Skip : Usually accompanies track search and allows the user to skip from the end of one track to the beginning of the next missing out any blank or unrecorded passages on the tape.
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Audio coding mode : A parameter in Dolby Digital surround-sound format which refers to the number of channels and their location in for form F/R, where F is the number of front channels and R is the number of rear channels. For example, 5-channel surround is called 3/2 mode, stereo is 2/0, and mono is designated 1/0.
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Audio enhancer : Any dynamic signal processing device that in some sense improves a dull or lifeless sound. It can be a simple as EQ or a complex DSP algorithm. Examples of exciters are the Aphex Aural Exciter, BBE Sonic Maximizer, or SPL Vitalizer. Enhancers combine dynamic equalization with either harmonic synthesis or phase manipulation.
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Audio frequency : See AF.
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Audio silence : A type of diagnostic recording made with the recording set-up as planned, but with all faders down. Used to make a reference measurement of the noise floor and/or a tape of biased noise.
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Audio taper : A type of potentiometer designed for use as a volume control in audio equipment where the resistance varies in a logarithmic, rather than a linear, fashion with rotation of the knob. This gives a better correlation between control rotation and the subjective loudness of the signal.
Audio-to-MIDI : Software or hardware that takes a monophonic instrumental or vocal line, analyzes the pitches, amplitude, and timbre, and converts the line to MIDI notes, complete with pitch-bend, MIDI velocity and volume, and possibly additional controller data.
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AudioX : An open MIDI driver specification/standard being promoted by Cakewalk™.
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Auditory masking : See frequency masking, masking.
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Augmentation : (1) The increase of a major or perfect interval by one half-step to make an augmented interval. (2) The appearance of a musical idea in note durations which are longer than those used for its first appearance. This technique was often used in the ployphonic music of the middle ages and renaissance, as well as in contrapuntal music (e.g., fugues) of the baroque and later periods.
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Aural : Of, relating to, or perceived by the ear.
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Auto-assembly : In on-line editing, the process by which the edit-programmer produces the edited video master tape according to the instructions on the EDL, without human intervention. This is only possible where footage is consistently lit and exposed.
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Auto-input : One of the electronic operating modes of a multitrack recorder. When auto-input is selected, all channels will remain in sel-sync playback mode until the machine is placed in record mode. Any channels that are in "ready " status will then begin recording and will automatically pass their input signals direct to their outputs. When recording is stopped, these channels return to sel-sync playback mode. Also called stand-by mode.
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Autolocator : A device for controlling the transport system of a tape recorder, allowing timecodetime code referencing such as SMPTE. Usually a number of locate points can be stored by the device. Some sequencers have an autolocate facility. Also called zero locate.
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Automatic Volume Control : See AVC.
Automation : A system where manual control of a process is replaced or enhanced by computer control, such as mixing desk automation where faders, mutes, and equalization can be controlled in part or in whole by a computer. In write mode, the automation system produces a continuous record of all the actual fader settings and adjustments made by the engineer during a mix. Most systems allow changes on replay, while remembering and recreating previous manipulations of other tracks. The level changes are recorded and recreated by VCAs in each input module of the console. The VCA-produced data can be recorded directly onto a track of the multitrack tape, giving a continuous record of all mixdown fader settings. Or, the VCA outputs can be recorded onto a separate disk. In the latter system, alignment of the fader data with the multitrack master tape is achieve by referring to a common SMPTE timecodetime code recorded on the tape and disk systems. See mute mode, mute-write, null-point, read mode, snapshot automation, update mode, write mode.
Autopanner : A device for processing a signal so that it can be made to appear at various positions in a stereo image via a remote control or MIDI commands.
Autostore : Benefits the long distance driver by scanning the waveband in the area of travel and automatically storing five or six strongest station in order of signal strength.
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Aux or auxiliary : An assignable, line-level input with no dedicated input source. Generally refers to an input connector in a preamplifier or integrated amplifier, signal processor, mixer, effects device, etc. The aux input has no de-emphasis or other special equalization and accepts line-level signals. Tone controls onf a preamp usually also affect signals sent to the aux input.
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Aux section : A smaller, independent mixer within the main mixing console which has an output consisting of a mix of everything going into the channels on which the appropriate effects send been turned up.
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Auxiliary : A bus allowing a signal to be sent from a mixing desk prior to the main output, usually to provide an input to effects. See effects send.
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Auxiliary envelope : An extra envelope in a synthesizer that, instead of being hard-wired to a filter or amplitude, is intended as a modulation source that can be applied to various destinations.
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Auxiliary messages : A classification of MIDI messages which includes Active Sensing, All Notes Off, Local On/Off, and Reset, and which describes whether the particular MIDI device responds to any of thsese messages.
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Auxiliary send : Also called aux send. See effects send, insert point.
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AVC : Automatic Volume Control. A circuit which adjusts the gain of an audio device in inverse proportion to the incoming signal level. An example is a portable tape recorder which is designed for speech recording; when the speaker is close to the microphone, the gain is reduced so as not to overload the tape. Also, a circuit which increases a TV or radio receiver’s gain when it is tuned to weak stations and decreases the gain when it is tuned to strong stations. Called AGC (Automatic Gain Control) in TV.
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AVI : Audio Video Interleaved. Microsoft’s answer to Apple’s QuickTime, and not compatible with Macs.
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Avid : A brand of nonlinear video editing system, which, while not being exactly an industry standard, is the most commonly used digital video editing system.
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Axis : In microphones, the direction of maximum sensitivity, generally perpendicular to the surface of the diaphragm or ribbon. In loudspeakers, the line projecting through the center of the voice coil toward the listening area. This is usually the direction in which the speaker exhibits the best overall frequency response. See acceptance angle, off-axis, directional microphone, polar pattern.
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Azimuth : In a tape recorder, the azimuth is the angle that the gap in the record or playback head makes with the direction of the tape travel, and it must be precisely 90Ëš to ensure proper high-frequency performance.
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