When the Sustain Time (rise) slider is set to its center value, the Sustain (S) Level slider behaves like the sustain parameter of a standard synthesizer ADSR envelope.
In this position, the Sustain (Level) slider defines the level that is sustained while the key remains depressed, following completion of the Attack time and Decay time phases.
The Sustain Time slider defines the time it takes for the level to rise from the Sustain level back to its maximum level—or to fall to zero:
Settings in the lower half of the Sustain Time slider range (fall) determine the time required for the level to decay from the sustain level to zero. The lower the slider position, the faster the sound level decays.
Settings in the upper half of its range (rise) determine the time required for the level to rise from the sustain level to its maximum value. The higher the slider position, the faster the sound level rises.
Set up a modulation routing as follows: modulation target Env3Dec, source Kybd.
Make sure the Intensity slider is set to a negative value.
Adjust Env3 settings.
This routing simulates the behavior of pianos and plucked instruments, where high notes decay faster than low notes.