Tremolo

A periodic fluctuation or oscillation in the amplitude of a tone, thereby being a type of amplitude modulation, and a limited version of a vibrato. It is used in various forms by instrumentalists but the optimum speed is usually regarded as being seven cycles per second. Tremolo is often heard with the vibraphone and certain types of electronic organ sounds.

Compare: Beats, Grain, Modulation, Trill, Vibrato.