Tremolo is the rapid repetition of a single note or the rapid alternation between two notes. On string instruments it is produced by quick up-and-down bow strokes; on the piano by rapid alternation of the hands or fingers; on other instruments by analogous techniques.

The effect can create tension, excitement, or a shimmering texture. Composers use measured tremolo, in which the exact rhythm is specified, or unmeasured tremolo, left to the performer’s discretion. In orchestral writing, string tremolo often underpins dramatic or atmospheric passages.

Executing an even, controlled tremolo requires relaxed yet precise muscle control. Uneven tremolo can sound nervous rather than expressive. The technique appears in music from the Baroque period to the present and remains a standard part of instrumental vocabulary.

• Rapid repetition or alternation of notes
• Used for tension or shimmering effect
• Produced by different techniques on different instruments
• Can be measured or unmeasured