SignalProcessing.Compute.AudioRelated.SignalEnvelope
$x'[n] = \mathrm{A}[n] \, x[n]$
The parameters attack, decay,
sustain time, and release
are given as percentages of the total envelope length. Together with the
sustain level input, these parameters control
the shape of the envelope:
$A[n]$
$n$
Attack
Decay
Sustain Time
Sustain Level
Release