Novation V-Station - Attack time; Decay time; Sustain level; Release time

Amplifier / Envelopes
When controlling volume, these controls adjust the following phases of the envelope as
shown in the illustration.
Attack time Adjusts the time it takes when a key is pressed for the envelope to
climb from zero to full volume. It can be used to create a sound with a
slow fade in.
Decay time Adjusts the time it takes for the envelope to decay from full volume to
the level set by the Sustain control while a key is held down.
Sustain level Sets the level that the envelope remains at while the key is held down,
after the decay time has expired.
Note : It is important to realise that the SUSTAIN parameter is a level control, not one that sets
time like the other envelope controls.
Release time Adjusts the time it takes when key is released from the sustain level to
zero. It can be used to create sounds that slowly fade away in volume
after you have taken your finger(s) off the keyboard.
17 Synthesis Tutorial