Polyrhythm
Two or more different equal divisions of the same span of time sounding together
Related
Polyrhythm divides the same span of time into different equal parts in different voices, as in three against two or five against four. Each layer is even, and their least common multiple sets the cycle. Slow, the attacks are clear; fast, the result is more a colour or groove.
It can be notated with tuplets, or with one layer on the beat and another in triplets or quintuplets. West African drumming, jazz and metal use it for drive; performers find a common denominator and align the layers to it.
Polyrhythm is not a synonym for cross-rhythm. Polyrhythm stresses different equal divisions sounding together; cross-rhythm stresses a conflict of accent grouping with the metre, and can occur in a single line. Nor is it a composite metre, where one bar contains two metres, not two simultaneous divisions.
Sources
- 定义、记谱与实例参 The New Grove Dictionary of Music and Musicians, "Polyrhythm"；本文为原创表述
Used for fact-checking only; all prose is original.