aleatoric music
Aleatoric music, stochastic music or random music leaves some aspect of its creation to chance, or to be determined by its performer(s). Although the term aleatoric music was first used in the 1950s, Charles Ives and Henry Cowell were using these techniques much earlier, and in fact Mozart was interested in music created using dice (or alea, in Latin), creating a dice game to create fragments of music at random.
A selection of articles about aleatoric music
Echoes of Oblivion by Robert McCarney - Randomness Run Riot
Classical music news. Edward Chilvers - Idiosyncratic pianist Edward Chilvers has devised a dice and mathematical chart system 'to follow nature not convention'
Classical music news. Obituary - Georg Katzer (1935-2019)
CD Spotlight. Compositional Thought - Piano music by John Corigliano, recommended by Karen Haid. 'Oppens and Lowenthal give strong performances of this music.'
Ensemble. Museum Culture? - Experimental music by Cage, Cowell, Feldman, Rzewski, Satie and Wolff, heard by Malcolm Miller
Provocations - Alistair Hinton and Chad Wozniak discuss Patric Standford's recent 'Provocative Thoughts'