Envelope thumb|A signal and its envelope marked with red The timbre of a sound is also greatly affected by the following aspects of its envelope: attack time and characteristics, decay, sustain, release (ADSR envelope) and transients. Thus these are all common controls on professional synthesizers. For instance, if one takes away the attack from the sound of a piano or trumpet, it becomes more difficult to identify the sound correctly, since the sound of the hammer hitting the strings or the first blast of the player's lips on the trumpet mouthpiece are highly characteristic of those instruments. The envelope is the overall amplitude structure of a sound.
Envelope thumb|A signal and its envelope marked with red The timbre of a sound is also greatly affected by the following aspects of its envelope: attack time and characteristics, decay, sustain, release (ADSR envelope) and transients. Thus these are all common controls on professional synthesizers. For instance if one takes away the attack from the sound of a piano or trumpet, it becomes mor,e difficult to identify the sound correctly, since the sound of the hammer hitting the strings or the first blast of the player's lips on the trumpet mouthpiece are highly characteristic of those instruments. The envelope is the overall amplitude structure of a sound.