An envelope is a time-based controller used most commonly to map the volume of an instrument. There are four common controls associated with an envelope. These are Attack, Decay, Sustain and Release. Whilst envelopes are most commonly encountered to control amplitude, they can also be used to great effect on the filter cutoff and pitch.

The below diagram demonstrates the effect of an envelope on the amplitude of a signal.

© Nathan Boddy 2006 unauthorised copying or duplication prohibited.

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