Indeterminacy in music

Indeterminacy in music is a compositional approach that leaves some musical choices to chance or performer discretion. It ranges from chance operations during composition to open scores that permit varied performances.

Aleatoric music: Music in which chance or uncontrolled factors determine some compositional or performance outcomes. This closely related term describes music shaped by chance, though usage overlaps with indeterminacy.
John Cage: American composer whose works and writings made chance procedures and performer freedom central to experimental music. His chance-based compositions became major models for indeterminate music.
4′33″: John Cage's 1952 work in which performers remain silent while ambient sounds become the event of the performance. It shifts attention from prescribed notes to sounds no score can fully control.
Serialism: A compositional method that organizes musical parameters through ordered series of values. Serialism tightly predetermines relationships that indeterminate methods may leave open.
Chance music: Music whose elements are selected or arranged through random procedures. Chance procedures can determine decisions before a score reaches performers.
Chance operations: Procedures that use random or chance-based selection to make compositional decisions. Cage used chance operations to relinquish choices during composition.
Music of Changes: John Cage's 1951 piano work composed using chance procedures derived from the I Ching. It demonstrates chance determining details fixed in a composed score.
Total serialism: Serial composition that applies ordered series to multiple musical parameters, such as duration and dynamics. It systematizes musical decisions rather than delegating them to chance or performers.
Graphic notation: A musical notation system using visual forms, symbols, or spatial layouts beyond conventional staff notation. Nontraditional scores can leave performers to interpret visual instructions.
I Ching: An ancient Chinese divination text organized around sixty-four hexagrams. Cage used its coin-based method to generate decisions in some compositions.

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