Additive Rhythm and Divisive Rhythm - Additive Rhythm

Additive Rhythm

Additive, as opposed to divisive, rhythm, features nonidentical or irregular durational groups following one another at two levels, within the bar and between bars or groups of bars (Agawu 2003, 86). This type of rhythm is also referred to in musicological literature by the Turkish word aksak, which means "limping" (Braïloiu 1951; Fracile 2003, 198). In the special case of time signatures in which the upper numeral is not divisible by two or three without a fraction, the result may alternatively be called irregular, imperfect, or uneven meter, and the groupings into twos and threes are sometimes called "long beats" and "short beats" (Beck and Reiser 1998, 181–82).

The term additive rhythm is also often used to refer to what are also incorrectly called asymmetric rhythms and even irregular rhythms – that is, metres which have a regular pattern of beats of uneven length. For example, the time signature 4/4 indicates each bar is eight quavers long, and has four beats, each a crotchet (that is, two quavers) long. The asymmetric time signature 3 + 3 + 2/8, on the other hand, while also having eight quavers in a bar, divides them into three beats, the first three quavers long, the second three quavers long, and the last just two quavers long. These kinds of rhythms are used, for example, by Béla Bartók, who was influenced by similar rhythms in Bulgarian folk music, and in some music of Philip Glass, and other minimalists, most noticeably the "one-two-one-two-three" chorus parts in Einstein on the Beach. They may also occur in passing in pieces which are on the whole in conventional metres.