In Ottoman musical theory, aksak is a rhythmic system in which pieces or sequences, executed in a fast tempo, are based on the uninterrupted reiteration of a matrix, which results from the juxtaposition of rhythmic cells based on the alternation of binary and ternary quantities, as in 2+3, 2+2+3, 2+3+3, etc. The name literally means "limping", "stumbling", or "slumping", and has been borrowed by Western ethnomusicologists to refer generally to irregular, or additive meters.
In Turkish folk music, these metres occur mainly in vocal and instrumental dance music, though they are found also in some folksongs. Strictly speaking, in Turkish music theory the term refers only to the grouping of nine pulses into a pattern of 2+2+2+3. Some examples are shown below.[additional citation(s) needed]
|5||2+3||Türk Aksağı [Bulg: Paidushko]|
|7||2+2+3||Devr-i Turan [Bulg. Račenica]|
|3+2+2||Devr-i Hindi  [Bulg. Lesnoto, Četvorno]|
|9||2+2+2+3||Aksak [Bulg. Daychovo]|
|13||2+2+2+2+2+3||[Bulg. Elenino horo]|
|2+2+2+3+2+2||[Bulg. Krivo Sadovsko horo]|
|3+4+4+2||Şarkı Devr-i Revâni|
|18||(3+2+2) + (2+2+3+2+2)||[Bulg. Jove Malaj Mome]|
|25||(3+2+2) + (3+2+2) + (2+2+3) + (2+2)||[Bulg. Sedi Donka]|
The Belgian experimental rock group Aksak Maboul take their name from this rhythm.
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