The physical process by which a sound gradually dissappears from the audible spectrum until it no longer exists. Simply put, decay is the time that it takes for a note to die away once the musician has stopped producing the sound. The sound waves dissapate in much the same manner as waves produced by tossing a stone in a pond. Decay is a basic component of how a sound is defined. See envelope.<br><br>The rate of reduction of the audio signal generated in synthesizers from the peak level.