Page "Vibrato" Paragraph 3

There are some instances where one of the terms ( vibrato, tremolo ) is used to describe the effect normally associated with the other term.

For example, vibrato is sometimes referred to as tremolo, notably in referring to the vibrato arm of an electric guitar as a " tremolo arm ", which produces variations of pitch.

Conversely, the so-called vibrato unit built in to many guitar amplifiers produces what is known as tremolo in all other contexts.

See vibrato unit for a detailed discussion of this terminology reversal.