aleatory music (āˈlēətôrˌē) [key] [Lat. alea = dice game], music in which elements traditionally determined by the composer are determined either by a process of random selection chosen by the composer or by the exercise of choice by the performer(s). At the compositional stage, pitches, durations, dynamics, and so forth are made functions of playing card drawings, dice throwings, or mathematical laws of chance, the latter with the possible aid of a computer. Those elements usually left to the performers' discretion include the order of execution of sections of a work, the possible exclusion of such sections, and subjective interpretation of temporal and spatial pitch relations. Also called "chance music," aleatory music has been produced in abundance since 1945 by several composers, the most notable being John Cage, Pierre Boulez, and Iannis Xenakis.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.