Cross-beat

In music, a cross-beat or cross-rhythm is a specific form of polyrhythm. The term cross rhythm was introduced in 1934 by the musicologist Arthur Morris Jones (1889–1980). It refers to when the rhythmic conflict found in polyrhythms is the basis of an entire musical piece.

The term "cross rhythm" was introduced in 1934 by the musicologist Arthur Morris Jones (1889–1980), who, with Klaus Wachsmann, took-up extended residence in Zambia and Uganda, respectively, as missionaries, educators, musicologists, and museologists.

African cross-rhythm is most prevalent within the greater Niger-Congo linguistic group, which dominates the continent south of the Sahara Desert. (Kubik, p. 58) Cross-rhythm was first identified as the basis of sub-Saharan rhythm by A.M. Jones. Later, the concept was more fully explained in the lectures of Ewe master drummer and scholar C.K. Ladzekpo, and in the writings of David Locke. Jones observes that the shared rhythmic principles of Sub-Saharan African music traditions constitute one main system. Similarly, Ladzekpo affirms the profound homogeneity of sub-Saharan African rhythmic principles. In Sub-Saharan African music traditions (and many of the diaspora musics) cross-rhythm is the generating principle; the meter is in a permanent state of contradiction.

The cross-rhythmic ratio three-over-two (3:2) or vertical hemiola, is the most significant rhythmic cell found in sub-Saharan rhythms. The following measure is evenly divided by three beats and two beats. The two cycles do not share equal status though. The two bottom notes are the primary beats, the ground, the main temporal referent. The three notes above are the secondary beats. Typically, the dancer's feet mark the primary beats, while the secondary beats are accented musically.

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