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Glossary of Audio Terms: D - E



DAISY CHAIN: Term used to describe serial electrical connection between devices or modules.

DAMPING: In the context of reverberation, damping refers to the rate at which the reverberant energy is absorbed by the various surfaces in the environment.

DASH: Digital Audio Stationary Head. An open reel digital recording format. Such as Sony 3348

DAT: Digital Audio Tape. Recording medium

DATA: Information stored and used by a computer.

DATA COMPRESSION: A system used to reduce the amount of data needed to represent an audio signal, usually by discarding audio information that is being masked by more prominent sounds.

DAW (Digital Audio Workstation): Computer system used to aid the creation of music and the demise of recording studios.

dB: deciBel. Unit used to express the relative levels of two electrical voltages, powers or sounds.

dBm: Variation on dB referenced to 0dB = 1mW into 600 Ohms.

dBv: Variation on dB referenced to 0dB = 0.775 volts.

dBV: Variation on dB referenced to 0dB = 1 volt.

dB/Octave: A means of measuring the slope of a filter. The more dBs per octave, the sharper the filter slope.

DATA COMPRESSION: A system for reducing the amount of data stored by a digital system. Most audio data compression systems are so-called lossy systems as some of the original signal is discarded based on psychoacoustic principles designed to ensure that only components which cannot be heard are lost.

DC: Direct Current.

DCC: Stationary head digital recorder format developed by Philips. Uses a data compression system to reduce the amount of data that needs to be stored.

dbx: A commercial encode/decode tape noise reduction system that compresses the signal during recording and expands it by an identical amount on playback.

DCO: Digitally Controlled Oscillator.

DDL: Digital Delay Line.

DE-ESSER: Device for reducing the effect of sibilance in vocal signals ( the ESSS and SHH sounds) There was a number of manufactures that made hardware De-essers. Examples such as DBX 901, BSS did a range of De-esser equipped units and a classic unit, Audio Design Compex. Plugins have pretty much taken over the duty of De-essing, Waves De-esser, Sonnox and the standard pro-tools De-esser being very good examples of this.

DECAY: The progressive reduction in amplitude of a sound or electrical signal over time.

DECCA TREE: Microphone technique developed in the early 50’s by DECCA engineers for stereo orchestral recordings. The technique uses 3 spaced omni-directional microphones ( Usually Neumann M50 ) in a upside down “T” formation. The L+R are spaced 2m apart and the C microphone 1.5m. The DECCA tree is positioned around 10ft above the conductors head using a high quality heavy duty mic stand from someone like Manfrotto. Check out some of the DECCA records from that period, superb sounding records. 

DEFRAGMENT: The process of rearranging the files on a hard disk so that all the files are as contiguous as possible, and that the remaining free space is also contiguous.

DETENT: Physical click stop in the centre of a control such as a pan or EQ cut/boost knob.

DI:  Direct Inject, where a signal is plugged directly into an audio chain without the aid of a microphone.

DI BOX: Device for matching the signal level impedance of a source to a tape machine or mixer input. Industry standard was the BSS AR116 . Some very good ones now available from Radial and the Rolls Royce of DI’s the Avalon U5.

DIGITAL: Electronic system which represents data and signals in the form of codes comprising 1s and 0s.

DIGITAL DELAY: Digital processor for generating delay and echo effects. Studio standards. AMS 1580, Roland SDE 3000, Lexicon PCM42, TC Electronic 2290

DIGITAL REVERB: Digital processor for simulating reverberation. Studio standards. Lexicon making the majority of them. Also AMS RMX15, TC Electronic, Yamaha

DIN CONNECTOR: Consumer multipin signal connection format, also used for MIDI cabling. Various pin configurations are available.

DIRECT COUPLING: A means of connecting two electrical circuits so that both AC and DC signals may be passed between them.

DITHER: Addition of low level random noise to reduce quantization distortion in digital sytems

DISK: Abbreviation of Diskette, but now used to describe computer floppy, hard and removable disks.

DISTORTION: The unwanted change in waveform which can occur between two points in a transmission equipment or system

DMA: Direct Memory Access :Part of a computer operating system that allows peripheral devices to communicate directly with the computer memory without going via the central processor or CPU.

DOLBY: Noise reduction system named after its inventor. Dr Ray Dolby

DOS: Disk Operating System. Part of the operating system of PC and PC compatible computers

DSP: Digital Signal Processor. A powerful microchip used to process digital signals.

DROP IN/OUT: Going into record and then out of record. 

DRIVER: Piece of software that handles communications between the main program and a hardware peripheral, such as a soundcard, printer or scanner.

DRY: A signal that has had no effects added.

DUBBING: Adding further material to an existing recording. Also known as overdubbing.

DUCKING: A system for controlling the level of one audio signal with another. For example, background music can be made to 'duck' whenever there's a voice over. 

DYNAMIC MICROPHONE: A type of microphone that converts audio into electrical signal by a small induction coil attached to a diaphram which moves inbetween two magnets. This movement in the magnetic field of the magnets causes a varying current in the coil through elecctro magnetic induction.   Shure SM57 /SM58 probably the worlds most popular microphone

DYNAMIC RANGE: The range in dB between the highest signal that can be handled by a piece of equipment and the level at which small signals disappear into the noise floor.

DYNAMICS: Way of describing the relative levels within a piece of music. 



EARLY REFLECTIONS: The first sound reflections from walls, floors and ceilings following a sound created in an acoustically reflective environment.

EBU: European Broadcasting Union

EFFECT (FX): Device used to manipulate audio signal in a creative or uncreative way. Such effects are usually made up of delay circuits or reverb

EFFECTS LOOP: Connection system that allows an external signal processor to be connected into the audio chain.

EFFECTS RETURN: Additional mixer input designed to accommodate the output from an effects unit.

ELECTRET MICROPHONE: Type of capacitor microphone utilizing a permanently charged capsule.

ENHANCER: A device designed to brighten audio material using techniques such as dynamic equalization, phase shifting and harmonic generation.

ENGINEER: The person/s used to under take all of the technical aspects of a music recording session, also the person to blame by the producer when the session goes wrong, the engineer subsequently blames the assistant engineer. 

ENVELOPE: The way in which the level of a sound or signal varies over time.

ENVELOPE GENERATOR: A circuit capable of generating a control signal which represents the envelope of the sound you want to recreate. This may then be used to control the level of an oscillator or other sound source, though envelopes may also be used to control filter or modulation settings. The most common example is the ADSR generator.

EQUALISER (EQ): Equipment used to boost or cut selected frequency.

ERASE: To remove data.

EXCITER: Used to enhance audio signal by means of dynamic equalization, harmonic distortion, high frequency enhancement and phase shift. Aphex Aural Exciter being one of the first to be developed in the mid 70’s and was horrendously expensive to hire. Now available as a plugin. SPL and BBE also manufactures of exciter products.

EXPANDER: A devise designed to decrease the level of low level signals and increase the level of high level signals, thus increasing the dynamic range of the signal.

EXPANDER MODULE: Synthesizer with no keyboard, 19” rack mountable or in some other compact format. 

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