
The letters A, D, S &R are the first letters of: Attack, Decay, Sustain and Release. These are the various elements of volume changes in the sounding of a keyboard instrument.
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http://www.encyclo.co.uk/local/20447

Attack, Decay, Sustain, and Release are the four parameters found on a basic synthesizer envelope generator, and they match the physical attributes of naturally occurring sound. An envelope generator is sometimes called a transient generator. The Attack, Decay, and Release parameters are rate or time controls. Sustain is a level. When a key is ...
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http://www.encyclo.co.uk/local/20532

Attack/decay/sustain/release, the four segments of a common type of 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. See envelope.
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http://www.encyclo.co.uk/local/22285

Attack, Decay, Sustain, Release. The four sections of every sound's envelope. (WW)
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http://www.encyclo.co.uk/local/22286

Attack, Decay, Sustain, Release
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http://www.encyclo.co.uk/visitor-contributions.php

Simple envelope generator with Attack, Sustain, Decay and Release parameters.
Found on
http://www.songstuff.com/glossary/A

Attack, Decay, Sustain and Release are the four stages of an envelope that describe the shape of a sound over time. Attack represents the time the sound takes to rise from an initial value of zero to its maximum level. Decay is the time for the initial falling off to the sustain level. Sustain is the time during which it remains at this level. Rele...
Found on
http://www.traditionalmusic.co.uk/music%20tech%20glossary/Music%20Tech%20Gl
No exact match found.