Stochastic Music

Stochastic music is a method of composition, formulated by *Iannis Xenakis* in the 1950s, in which the laws of probability govern the distribution of musical events. Rather than determining every note, the composer specifies statistical parameters — densities, distributions and limits — from which masses of sound, Xenakis's "clouds" and "galaxies" of glissandi, pizzicati and percussion, are generated. Applied first to orchestral works such as "Metastasis" and "Pithoprakta", and later computed with the ST programme and the UPIC system, the approach was Xenakis's answer to the perceived impasse of serialism, and it extended to electroacoustic music.