Aleatoricism

Aleatoricism or aleatorism, the noun associated with the adjectival aleatory and aleatoric, is a term popularised by the musical composer Pierre Boulez, but also Witold Lutosławski and Franco Evangelisti, for compositions resulting from "actions made by chance", with its etymology deriving from alea, Latin for "dice". It now applies more broadly to art created as a result of such a chance-determined process. The term was first used "in the context of electro-acoustics and information theory" to describe "a course of sound events that is determined in its framework and flexible in detail", by Belgian-German physicist, acoustician, and information theorist Werner Meyer-Eppler. In practical application, in compositions by Mozart and Kirnberger, for instance, the order of the measures of a musical piece were left to be determined by throwing dice, and in performances of music by Pousseur (e.g., Répons pour sept musiciens, 1960), musicians threw dice "for sheets of music and cues". However, more generally in musical contexts, the term has had varying meanings as it was applied by various composers, and so a single, clear definition for aleatory music is defied. Aleatory should not be confused with either indeterminacy, or improvisation.