In music, the absence of specific instruction concerning a significant element of a composition. A mobile piece is unspecific in terms of the order of sections; a graphic score is indeterminate in notation or timing. All music is indeterminate to some degree, since no two live performances can be totally alike.
Indeterminacy as an esthetic goal of the avant-garde c. 1950–70 aims, by stripping away the means of achieving an exact performance, to reestablish extemporization as an element of virtuosity, and to provoke new discoveries. With the aid of multichannel tape recording, pop musicians in the 1970s developed an art of composing by experiment from taped initial ideas. Composers of indeterminate music include Berio, Stockhausen, and the Polish composer Roman Haubenstock-Ramati (1919– ). After 1970, indeterminacy became a music education cause, aimed at releasing repressed creativity.