Vibrato

A periodic fluctuation or oscillation in the frequency of a tone, thereby being a type of frequency modulation. It is also usually accompanied by a pulsation of intensity which affects the timbre or colour of the tone. Instrumentalists and singers use the effect to enrich their tone, and usually regulate the speed of the vibrato to the range of seven cycles per second.

Compare: Flutter, Grain, Modulation, Tremolo, Trill, Wow.