Aleatoric music

The term became known to European composers through lectures by acoustician Werner Meyer-Eppler at the Darmstadt International Summer Courses for New Music in the beginning of the 1950s.

(Such dice games are attributed to Carl Phillip Emanuel Bach, Franz Joseph Haydn, and Wolfgang Amadeus Mozart.)

[clarification needed] One of these, Erratum Musical, written with Duchamp's sisters Yvonne and Magdeleine[5] for three voices, was first performed at the Manifestation of Dada on 27 March 1920,[6] and was eventually published in 1934.

Two of his contemporaries, Francis Picabia and Georges Ribemont-Dessaignes, also experimented with chance composition,[clarification needed] these works being performed at a Festival Dada staged at the Salle Gaveau concert hall, Paris, on 26 May 1920.

[citation needed] American composer John Cage's Music of Changes (1951) was "the first composition to be largely determined by random procedures",[7] though his indeterminacy is of a different order from Meyer-Eppler's concept.

[9] Later American composers, such as Alan Hovhaness (beginning with his Lousadzak of 1944) used procedures superficially similar to Cowell's, in which different short patterns with specified pitches and rhythm are assigned to several parts, with instructions that they be performed repeatedly at their own speed without coordination with the rest of the ensemble.

[10] Some scholars regard the resultant blur as "hardly aleatory, since exact pitches are carefully controlled and any two performances will be substantially the same"[11] although, according to another writer, this technique is essentially the same as that later used by Witold Lutosławski.

[14] In Europe, following the introduction of the expression "aleatory music" by Meyer-Eppler, the French composer Pierre Boulez was largely responsible for popularizing the term.

[16] A form of limited aleatory was used by Witold Lutosławski (beginning with Jeux Vénitiens in 1960–61),[17] where extensive passages of pitches and rhythms are fully specified, but the rhythmic coordination of parts within the ensemble is subject to an element of chance.

In John Cage's Music of Changes (1951), for example, the composer selected duration, tempo, and dynamics by using the I Ching, an ancient Chinese book which prescribes methods for arriving at random numbers.

However, "open form" in music is also used in the sense defined by the art historian Heinrich Wölfflin[23] to mean a work which is fundamentally incomplete, represents an unfinished activity, or points outside of itself.

[28][page needed] Examples of extensive aleatoric writing can be found in small passages from John Williams' score for the film Images.