The Columbia Encyclopedia, Sixth Edition. 2001-07.
rhythm
the basic temporal element of music, concerned with duration and with stresses or accents whether irregular or organized into regular patternings. The formulation in the late 12th cent. of the rhythmic modes—basic recurrent patterns that were adhered to in composition—began the development of the Western system of meter and its notation. Most rhythms are metrical, i.e., the values are multiples of a temporal unit, or beat, usually associated with some particular note value. Free rhythm, such as occurs in much Asian music, has no meter (i.e., its temporal values are not derived from a basic unit). The degree of rhythmic complexity and the types of rhythms used are major considerations in analysis of the style of a composer or a period. The rhythmic tension of music is of value in eliciting emotional response from the hearer. African music and some 20th-century composers employ polyrhythm, the simultaneous use of several rhythmic patterns whose accents do not coincide. See syncopation and metronome.
