Decay

On a synthesizer, decay is the time it takes for the sound to fade from its highest level, determined by the attack stage, to the sustain level. It regulates the amplitude envelope of the sound and is typically found in the envelope section of a synthesizer. The four stages of the amplitude envelope—a graph that depicts how a sound’s volume changes over time—are attack, decay, sustain, and release.

The decay stage, which follows the attack stage in the amplitude envelope, determines how long the sound will fade from its peak level to the sustain level. A sound will diminish more quickly with a shorter decay time than it will more gradually with a longer decay time.

The decay parameter can produce various effects and is particularly helpful for modifying the sound of percussive instruments like drums and plucked instruments. Longer decay times can create more natural and smooth sounds, while shorter decay times can produce sharp and percussive sounds.