Comps 20th Century Terms

music in whcih the composer employs elements of chance, either in fashioning the composition itself or in prescribing conditions of performance, or both; also referred to as indeterminancy. The term "chance music" is preferred by many composers. The indeterminanate aspect may affect the act of composition, the performance, or both. In the first instance, some random process, such as throwing dice (the original meaning of aleatory being "according to the throw of a die"), is used to fix certain compositional decisions; e.g., the choice of pitches or rhythmic values. In the second, the performer makes certain compositional decisions in a given realization of a piece: e.g., the number of segments played or the order in which they are played or the specific pitches or durations used. Principally a phenomenon of the later 20h century, the music of John Cage is a notable example of aleatoric music. Music of Changes, a piano piece composed in 1951, was the first composition to be largely degermined by random procedures. Other important composers of this style include Earle Brown, Karlheinz Stockhausen, and Robert Morgan.