metric modulation
A technique where a note value from the current tempo becomes the basis for a new tempo, creating a precise, mathematically related tempo change.
In Depth
Metric modulation (a term coined by composer Richard Wuorinen, though the technique is most associated with Elliott Carter) uses a shared note value as a bridge between two tempos. For example, if the current tempo is quarter note = 120 and the composer establishes that the previous triplet eighth note equals the new eighth note, the new tempo is mathematically determined. This creates tempo changes that are precise, perceptible, and structurally meaningful rather than arbitrary.
Elliott Carter developed metric modulation into a sophisticated compositional language, using it to create works where different instrumental parts appear to exist in independent temporal worlds that periodically align. His String Quartets Nos. 1–5 are landmarks of the technique. The concept has spread beyond classical music: progressive rock bands like Tool use metric modulations extensively, and the technique appears in jazz (particularly in the work of drummer Vinnie Colaiuta) and in film scoring, where mathematically precise tempo transitions create subliminal structural coherence.
Elliott Carter was still composing works with complex metric modulations in his late 90s, completing his last piece at age 103 — making him the longest-lived major composer in history.