An “envelope” refers to a voltage-controlled signal generator that creates a time-varying voltage shape, which is typically used to modulate various parameters of a synthesizer, such as amplitude, filter cutoff frequency, or modulation depth. Envelopes are a crucial component in shaping the dynamic and expressive characteristics of synthesized sounds.
Envelopes have different stages that define the shape of the voltage curve over time. The most common type of envelope is the ADSR (Attack, Decay, Sustain, Release) envelope, but there are other types as well, such as AD (Attack, Decay), AR (Attack, Release), and more complex forms like DADSR (Delay, Attack, Decay, Sustain, Release) and AHDSR (Attack, Hold, Decay, Sustain, Release).
