organum

organum (ôr`gənəm), in music, compositional technique, developed in Europe during the 10th cent., in which each note of Gregorian chant melody was doubled by another note. In the earliest examples, called parallel organum, the doubling interval was constant, usually the lower fourth or fifth. In the 12th cent., composers began to apply a rapidly moving voice against the slow moving chant melody; the resulting compositions had two or more independent melodies and can be considered the beginning of polyphonic music.

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organum

Early polyphonic setting of plainchant (see Gregorian chant), the earliest form of counterpoint. The oldest written organum (c. 900), which evidently reflects a prevailing improvisational practice, consists of two lines moving simultaneously, note against note, the added line often paralleling the chant line a fourth or a fifth below. Later the added line acquired greater melodic individuality and independence. Organum consisting of more than one note against each chant note (florid or melismatic organum) appeared by the early 12th century. Three- and four-voice organum were first composed by the Notre-Dame school. Organum died out with the advent of the 13th-century motet.