Sound Engineer's Glossary

Attack The first part of a sound. On a compressor/limiter, a control that affects how that device will respond to the attack of a sound.

Attenuation A decrease in level.

Automation A system that memorizes, then plays back the position of all faders and mutes on a console.

Bandwidth The number of frequencies that a device will pass before the signal degrades. A human being can supposedly hear from 20Hz to 20kHz, so the bandwidth of the human ear is 20 to 20kHz.

Bass Management A circuit which utilizes the subwoofer in a 5.1 system to provide bass extension for the five main speakers. The Bass Manager steers all frequencies below 80Hz into the subwoofer along with the LFE (see LFE) source signal.

Bass Redirection Another term for Bass Management.

Bit Rate The transmission rate of a digital system.

Bit Splitter In order to record a signal with a 20-bit word length onto a recorder that is only 16-bit, the digital word is "split" across two tracks instead of one.

Buss A signal pathway.

Chamber (Reverb) A method to create artificial reverberation using a tiled room with a speaker and several microphones placed in the room.

Chorus A type of signal processor where a de-tuned copy is mixed with the original signal which creates a fatter sound.

Comb Filter A distortion produced by combining an electronic or acoustic signal with a delayed copy of itself. The result is peaks and dips introduced into the frequency response. This is what happens when a signal is flanged (see Flanging).

Cut Pass A playback of the song in which the engineer programs the mutes only into the automation computer in order to clean up the mix.

Cut To decrease, attenuate or make less.

Data Compression Takes multiple data streams (as in 6-channel surround sound) and compresses them into a single data stream for more efficient storage and transmission. Supposedly some of what is normally recorded before compression is imperceptible, with the louder sounds masking the softer ones. As a result, some of this data can be eliminated since it's not heard anyway. This selective approach, determined by psychoacoustic research, is the basis for "lossy" compression. It is debatable however, how much data can actually be thrown away (or compressed) without an audible sacrifice. Dolby AC-3 and DTS are both lossy compression schemes.

DAW A Digital Audio Workstation. A computer with the appropriate hardware and software needed to digitize and edit audio.

DDL Digital Delay Line. Same as a digital delay processor.

Decay The time it takes for a signal to fall below audibility.

Delay A type of signal processor that produces distinct repeats (echoes) of a signal.

Dolby Digital® A data compression method, otherwise known as AC-3, which uses psychoacoustic principles to reduce the number of bits required to represent the signal. Bit rates for 5.1 channels range from 320kbps for sound on film to 384kbps for digital television and up to 448kbps for audio use on DVD. AC-3 is also what's known as a "lossy" compressor (see Lossy Compression) that relies on psychoacoustic modeling of frequency and temporal masking effects to reduce bits by eliminating those parts of the signal thought to be inaudible. The bit rate reduction achieved at a nominal 384kbps is about 10:1.

Down-mix To automatically extract a stereo or mono mix from an encoded surround mix.

DTS A data compression method developed by Digital Theater Systems using waveform coding techniques that takes six channels of audio (5.1) and folds them into a single digital bit stream. This differs from Dolby Digital® in that the data rate is a somewhat higher 1.4Mbs, which represents a compression ratio of about 4:1. DTS is also what's known as a "lossy" compression (see Lossy Compression).

DTV Digital Television. Element A component or ingredient of the sound or groove.

Elliptical EQ A special equalizer built especially for vinyl disc mastering that takes excessive bass energy from either side of a stereo signal and directs it to the center. This was to prevent excessive low frequency energy from cutting through the groove wall and destroying the master lacquer.

Equalizer A tone control that can vary in sophistication from very simple to very complex (see Parametric Equalizer).

Exciter An outboard effects device that uses phase manipulation and harmonic distortion to produce high frequency enhancement of a signal.

5.1 A speaker system that uses three speakers across the front and two stereo speakers in the rear, along with a subwoofer.

Flanging The process of mixing a copy of the signal back with itself, but gradually and randomly slowing the copy down to cause the sound to "whoosh" as if it were in a wind tunnel. This was originally done by holding a finger against a tape flange (the metal part that holds the tape on the reel), hence the name.

Fletcher-Munson Curves A set of measurements that describes how the frequency response of the ear changes at different sound pressure levels. For instance, we generally hear very high and very low frequencies much better as the overall sound pressure level is increased.

Groove The pulse of the song and how the instruments dynamically breathe with it.

HDCD High-Definition Compatible Digital® is a process which encodes 20 bits of information onto a standard 16-bit CD, while still remaining compatible with normal CD players.

LFE Low Frequency Effects channel. This is a special channel of 5Hz to 120Hz information primarily intended for special effects such as explosions in movies. The LFE has an additional 10dB of headroom in order to accommodate the required level.

Make-up Gain A control on a compressor/limiter that applies additional gain to the signal. This is required since the signal is automatically decreased when the compressor is working. Make-up Gain "makes up" the gain and brings it back to where it was prior to being compressed.

MDM Modular Digital Multitrack. A low cost 8-track digital recorder that can be grouped together to configure as many tracks as are needed. The Tascam DA-88 and Alesis ADAT are the most popular MDMs.

MLP Meridian Lossless Packing. This is a data compression technique designed specifically for high quality (96kHz/24bit) sonic data. MLP differs from other data compression techniques in that no significant data is thrown away, thereby claiming the "Lossless" moniker. MLP is also a standard for the 96kHz/24bit portion of the new DVD-Audio disc and is licensed by Dolby Labs.

MO Magneto Optical. A re-writeable method of digital storage utilizing an optical disc. Each disc stores from 250MB to 4.3GB and may be double-sided. Its widespread use has been limited by its slow access time.

Modulate The process of adding a control voltage to a signal source in order to change its character. For example, modulating a short slap delay with a .5Hz signal will produce chorusing (see Chorus).

Parametric Equalizer A tone control where the gain, frequency and bandwidth are all variable.

Mute An On/Off switch. To mute something would mean to turn it off.

Phantom Image In a stereo system, if the signal is of equal strength in the left and right channels, the resultant sound appears to come from in between them. This is a phantom image.

Phase Shift The process during which some frequencies (usually those below lOOHz) are slowed down ever so slightly as they pass through a device. This is usually exaggerated by excessive use of equalization and is highly undesirable.

Plate (Reverb) A method to create artificial reverberation using a large steel plate with a speaker and several transducers connected to it.

Pre-delay A variable length of time before the onset of reverberation. Pre-delay is often used to separate the source from the reverberation so the source can be heard more clearly.

Pultec An equalizer sold during the 50's and 60's by Western Electric that is highly prized today for its smooth sound.

Q Bandwidth of a filter or equalizer.

Ratio A control on a compressor/limiter that determines how much compression or limiting will occur when the signal exceeds threshold.

Range On a gate or expander, a control that adjusts the amount of attenuation that will occur to the signal when the gate is closed.

Recall A system that memorizes the position of all pots and switches on a console. The engineer must still physically reset the pots and switches back to their previous positions as indicated on a video monitor.

Release The last part of a sound. On a compressor/limiter, a control that affects how that device will respond to the release of a sound.

Reverb A type of signal processor that reproduces the spatial sound of an environment (e.g., the sound of a closet or locker room or inside an oil tanker).

Punchy A description for a quality of sound that infers good reproduction of dynamics with a strong impact. Sometimes means emphasis in the 200Hz and 5kHz areas.

Return Inputs on a recording console especially dedicated for effects devices such as reverbs and delays. The Return inputs are usually not as sophisticated as normal channel inputs on a console.

SDDS Sony Dynamic Digital Sound. Sony's digital delivery system for the cinema. This 7.1 system features five speakers across the front, stereo speakers on the sides, plus a subwoofer.

Selsync Short for Selective Synchronization. This is the process of using the record head on a tape machine to do simultaneous playback of previous recorded tracks while recording. This process is now called overdubbing.

Sibilance A rise in the frequency response in a vocal where there's an excessive amount of 5kHz, resulting in the "S" sounds being overemphasized.

SMART Content System Management Audio Resource Technique. This feature allows the producer to control the way the multi-channel audio is played back in stereo by saving one of 16 mixdown coefficients as control information to a data channel on the DVD-A.

SPL Sound Pressure Level.

Synchronization When two devices, usually storage devices such as tape machines, DAW's or sequencers, are locked together with respect to time.

Sub Short for subwoofer.

Subwoofer A low frequency speaker with a frequency response from about 25Hz to 120Hz.

Tape Slap A method to create a delay effect by using the repro head of a tape machine (which is after the record head).

Threshold The point at which an effect takes place. On a compressor/limiter for instance, the Threshold control adjusts the point at which compression will take place.

Track Sharing When a single track shares more than one instrument. For instance, when a percussion part is playing on a guitar solo track in places that the guitar has not been recorded.

TV Mix A mix without the vocals so the artist can sing live to the back tracks during a television appearance.