tremolo

Tremolo is a volume modulation effect in which the guitar signal gets louder and quieter in a repeating pattern¹. It works by changing the volume of an input signal at a certain rate, and tremolo pedals rely on an LFO, or low-frequency oscillator, to cycle the volume². Virtually all tremolo pedals share rate and depth controls³. Tremolo is different from vibrato, which changes the pitch of the guitar rhythmically⁴. The effect has been included in guitar amps built as early as the 1940s⁵.