D/A converter
Short for "digital/analog converter"; a device that changes an analog signal into a digital signal that represents equivalent information via sampling.

DAT
Digital Audio Tape. A tape-based digital audio recording and playback system, developed by Sony, which use a sampling rate of 48 kHz (slightly higher than CDs, which use 44.1 kHz).

data dump
A packet of memory contents being transmitted from place to place (usually in the form of MIDI system-exclusive data) or stored to a RAM card.

dB
Short for "decibel"; a numerical expression for the relative (a logarithmic value) loudness of a sound. Different measures of dB such as dB u or dB V are used depending on the application and nominal value.

Decay
The period of an envelope during which a sound's attribute (such as volume) stabilizes after the attack has completed. When the sound attribute reaches the end of it's decay, it has reached the sustain period.

Delay
An effect that is used to add depth or space to an audio signal by repeating the input one or more times after a brief pause of a few milliseconds to a few seconds; also often referred to as echo.

Decoding
The process of converting a compressed audio format, like MP3, back into a form that can be played back.

Default
A selection automatically used by a computer program in the absence of a choice made by the user.

Destructive
"Destructive audio processing" means that the actual audio data in an audio file is changed as opposed to just editing peripheral or playback parameters.

Detune
Noun: A control that allows one oscillator to sound a slightly different pitch than another.
Verb: To change the pitch of one oscillator relative to another, producing a fuller sound.

Digital
Relating to an audio recording method in which sound waves are represented digitally (as on magnetic disk) so that in recordings wow and flutter are eliminated and background noise is reduced; also see analog.

digital-to-analog converter (DAC)
A device that changes the sample words put out by a digital audio device into analog fluctuations in voltage that can be sent to a mixer or amplifier. All digital synthesizers, samplers, and effects devices have DAC at their outputs to create audio signals.

digital signal processing (DSP)
Broadly speaking, all changes in sound that are produced within a digital audio device, other than changes caused by simple cutting and pasting of sections of a waveform, are created through DSP. A digital echo is a typical DSP function.

Digital Audio
Audio that has been sapled to get a number of data points that apporximate the original analog sound waves. Digital audio must be converted back to analog form for playback.

Digital Audio Extraction (DAE)
Reading digital audio directly from a CD, as opposed to playing it back and sampling the analog signal. DAE is also called 'ripping'.

Digital Rights Management (DRM)
A system that can track and manage listening and ownership of digital content.

DIMM
Short for "Dual In-line Memory Module"; board equipped with RAM memory components; it is plugged into appropriate slots on the mainboard.

DirectX
Sometimes incorrectly associated with ActiveX. A collection of  low-level hardware drivers and free package of software interfaces for developers (API -Application Programming Interface) that enables programs direct (=fast) access to hardware functions.
It was developed by Microsoft primarily for game programming, although it can also be used as a soundcard interface in audio programs, if the requisite drivers are available, and as an interface to your digital audio program's plug-in architecture.

DirectX Plug-In
A program that uses Microsoft's DirectX technology to obtain digital audio samples which are then manipulated by applying reverb, compression or some other type of audio signal effect. The output signal may be rendered off-line or generated in real-time while the plug-in's host program performs playback. See Plug-In for more details.

Disk At Once
CD-R recorder mode: All tracks are written to the CD-R without interruption. This mode is generally required to write CD audio format (Red Book audio). Not all CD-R recorders can operate in this mode (see Track At Once).

DMA
Short for "Direct Memory Access" - Here data transport operations between system components are executed without the help of the CPU (see Busmaster cards).

DMCA
Digital Millenium Copyright Act. Legistation that modified copyright law to make provisions for digital audio, including Webcasting.

DSP
1) Short for "Digital Signal Processor", a computer chip designed specifically for computing audio data. This type of chip is installed in some soundcards for computing effects and related data without the help of the CPU.
2) Digital Signal Processing uses mathmatics to operate on a digital signal (such as a digital audio stream) to generate some type of altered output. DSP is used heavily in software and hardware effects processing.

Dump
> data dump.

Duplex
This term goes way back to the days of the telegraph. Today in the context of soundcards, duplex mode refers to parallel operation of audio inputs and outputs. Half-duplex means that a soundcard does not support simultaneous recording and playback operation. Full-duplex means that you can use inputs and outputs simultaneously.

DVD
Short for "Digital Versatile Disk", a format that is the designated successor to contemporary CDs (see CD audio). These disks hold video and audio data. With massive storage capacity of seventeen gigabytes (equivalent to 25 conventional CDs); the projected format for audio DVD will be 24 bits/96 kHz, although the decision hasn't finalized by the powers that be.

dynamic voice allocation
A system found on many multitimbral synthesizers and samplers that allows voice channels to be reassigned automatically to play different notes (often with different sounds) whenever required by the musical input from the keyboard or MIDI.early reflections: A reverb algorithm whose output consists of a number of closely spaced discrete echoes, designed to mimic the bouncing of sound off of nearby walls in an acoustic space.