
Polyrhythm is the simultaneous use of two or more conflicting rhythms, that are not readily perceived as deriving from one another, or as simple manifestations of the same meter. The rhythmic conflict may be the basis of an entire piece of music (cross-rhythm), or a momentary disruption. Polyrhythms can be distinguished from irrational rhythms, wh...
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http://en.wikipedia.org/wiki/Polyrhythm

the simultaneous combination of contrasting rhythms in a musical composition. Rhythmic conflicts, or cross-rhythms, may occur within a single metre ... [1 related articles]
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http://www.britannica.com/eb/a-z/p/91

several rhythms at the same time.
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https://education.ket.org/resources/music-glossary/
No exact match found.