Glossary of Audio Terms: A - C
ABSORBTION: Damping of sound wave on passing through a medium or hitting a surface. Also, property possed by materials, objects or media of absorbing sound energy.
AC: Alternating Current.
A/D ( A to D) CONVERTER: Analogue to Digital Converter. Converts signal from the analogue domain into in to discrete digital numbers.
ACTIVE: Equipment which contains circuitry that needs power.
ACETATE Also called Lacquer disc. A disc for mechanical or electromechanical recording, usually made of metal, glass or fibre then coated with lacquer compound.
ADAT (ALESIS DIGITAL AUDIO TAPE) Developed by Alesis, ADAT is a eight-channel optical digital audio interface.
ADSR: Attack,Decay,Sustain, Release. Parameters found on envelope generators used in analogue synths
AES: Audio Engineering Society.
AES/EBU: Two channel digital audio interface developed by Audio Engineering Society and European Broadcasting Union. Usually connected via 3 pin XLR on a balanced cable of 110 Ohm impedance, it carries 2 digital signals and embedded clocking data.
AFL: After Fade listen. Generally found on mixing consoles which allows you to monitor the signal level set by the fader
AGC: Automatic Gain Control. Compression that brings up low level passages.
AIFF: A Type of audio file format
ALIASING: A form of intermodulation distortion caused when the sampling frequency is not at least twice the highest frequency component of the input signal
AMBIENCE: The combination of reverberation and background noise which characterizes the sound in a given hall or studio.
AMP: (Ampere) Unit of electrical current.
AMPLIFIER: Device that increases the level of an electrical signal.
AMPLITUDE: Magnitude of strength of signal or wave.
ANALOGUE: Electronic signal whose waveform resembles that of the original sound.
ANECHOIC CHAMBER: A chamber with no echo. Used to calibrate microphones.
ANTI-ALIASING FILTER: Used in A/D converters. A Filter used to limit the frequency range of an analogue signal prior to A/D conversion so that the maximum frequency does not exceed half the sampling rate.
ASRC: Asynchronous sample rate converter. A converter from one sample rate to another which can work with a wide relationship of input to output frequency, thus can deal with vari-speed rates.
ATTACK: In compressors and gates, the time taken to produce the necessary gain change.
AUDIO FREQUENCY: The sound audible to the human ear. 20 to 20,000 Hz
AUTO LOCATOR: Stored time points on tape machine or hard disk recorder for fast location.
AUX: (Send) Control on a mixing console channel used to send proportion of the signal to external device such as a effect unit or to create a separate monitor mix.
AUX RETURN: Where the output, usually from a effect unit, returns back into the console with its own designated section of level and mute controls.
AZIMUTH: The angle between the gap in a tape head and the longitudinal axis of the tape (should be 90 degrees)
BACKUP: A safety copy
BAFFLE: Used to separate sound radiations
BALANCE: The relative levels of instruments and vocals within a mix.
BALANCED LINE: Cable which uses two out-of-phase conductors and a common screen to reduce the effect of interference.
BANDPASS: A filter that only passes frequencies of a specified range.
BANDWIDTH: Frequency span passed by an electronic circuit.
BETA VERSION: Software which is not fully tested and may include bugs.
BI-DIRECTIONAL: Type of microphone which has a figure of eight direction pattern.
BIAS: In analogue tape recording bias is a very high frequency which is mixed with the audio signal at the record head of the machine, generally a sine wave of 100Khz and above, this makes the tape work more in its linear operating range. If this is not applied the tape will retain very little magnetism and distort.
BINARY: Counting system based on only two states, 1s and 0s.
BIOS: Part of a computer operating system held on ROM rather than on disk. This handles basic routines such as accessing the disk drive.
BIT: Binary digit, which will either be 1 or 0.
BITRATE: Speed in number of bits per second
BLUMLEIN: Two Bi-directional ( Fig 8) microphones placed in the same point and angled 90 degrees to each other to create a stereo image. Developed by Alan Blumlein an English gentleman who was also heavily involved with the development of radar.
BOOST/CUT CONTROL: Found on equalizers, the selected frequency can either be amplified ( boost) or attenuated ( Cut)
BOUNCING: The process of mixing two or more recorded tracks together and re-recording these onto another track.
BPM: Beats Per Minute.
BUFFER: Temporary storage area for data to be transported to either another system, or to somewhere else within the same system.
BUSS: Where multiple signals are brought together. For example, a buss bar in a console is where all the individual grounds paths are brought together.
BYTE: A binary word that is 8 bits long.
CANS: Slang term for headphones
CARDIOID: Heart shaped polar response of a microphone
CAPACITANCE: The capability of a circuit to store electrical charge.
CAPACITOR: Electrical component exhibiting capacitance.
CAPACITOR ( OR CONDENSER ) MICROPHONE: Type of microphone in which a electrical signal is generated due to the variation in capacitance between the diaphragm and fixed plate. Too many to list but the most popular Neumann U87
CD-R: Compact Disk Recordable
CD-R BURNER: Equipment used to record data or audio to a CD-R.
CHANNEL: On a mixing console. A strip of controls usually EQ, Dynamics, Aux controls, routing etc.
CHANNEL: In MIDI, Channel refers to one of 16 possible data channel over which MIDI data may be sent. The organisation of data by channels means that up to 16 different MIDI instruments or parts may be addressed using a single cable.
CHASE: Where a slave device syncs to a master device. Usually using timecode as the sync.
CHIP (IC): Integrated circuit.
CHORUS: Effect created by doubling a signal and adding delay and pitch modulation.
CLICK TRACK: Metronome pulse which sometimes assists musicians in playing in time.
CLIPPING: Severe form of distortion which occurs when a signal attempts to exceed the maximum level which a piece of equipment can handle.
CLONE: Exact duplicate. Often refers to digital copies of digital tapes.
COMMON MODE REJECTION: A measure of how well a balanced circuit rejects a signal that is common to both inputs.
COMPRESSOR: Device used to reduce the dynamic range of audio signals.
COMPUTER: A device for the storing and processing digital data. Also used to put recording studios out of business.
CONDUCTOR: Material that provides a low resistance path for electrical current.
CONSOLE: Also known as mixing desk. A device that combines all the separate instruments and voice’s to produce a finished song. Usually the most impressive piece of equipment in a studio. Used to be found in recording studios. Popular mixing desks, Neve, SSL, API etc.
CONVOLUTION: Technique used in DSP design that is a mathematical way of combining two signals to form a third signal. The two signals consist of the input and the impulsive response which allows the third ( the output) to be calculated.
COPY PROTECTION: Method used by software manufacturers to prevent un-authorised copying, that doesn’t really work.
CRASH ( SHIT!): Slang term relating to a malfunction of computer program and maybe the loss of 10 hours work due to not saving.
CUT AND PASTE EDITING: The ability to copy or move sections of a recording to new locations.
CUTOFF FREQUENCY: The frequency above or below which attenuation begins in a filter circuit.
CYCLE: One complete vibration of a sound source or its electrical equivalent. One cycle per second is expressed as 1Hertz (Hz).
CV: Control voltage used in analogue synthesizers, to control oscillator or filter frequency. The old school way of controlling analogue synths before MIDI.