Elec. computers have so far been used in two ways by composers: (a) to aid pre‐compositional calculations and (b) to produce elec. sound. They have also been used to analyse works, to study comp. styles, and to prod. systems of notation. Among the first composers to use a computer was the Amer. Lejaren Hiller, who used the Illiac computer to ‘compose’ a piece of mus. by feeding into it a program comprising Fux's rules for 16th‐cent. modal counterpoint and others relating to 20th‐cent. serialism. The result was the Illiac Suite for String Quartet (1957). Excluded from the program were all notes that broke the rules, so the computer chose at random from the remaining possibilities. In later Hiller works, such as Computer Cantata (1963), notes and intervals were not chosen at random but according to weighted probabilities, e.g. a note was chosen according to the implications of the previously chosen note. Another composer, Xenakis, used the computer for sound effects rather than for comp. processes. In his Metastaseis for orch. (1953–4) the computer calculates glissandi at different speeds.
(a) to aid pre‐compositional calculations and (b) to produce elec. sound. They have also been used to analyse works, to study comp. styles, and to prod.
A computer works musically by producing ‘waveforms’. Developments involving the ‘digital analogue converter’ meant that waveforms could be created which perfectly simulate instr. sounds. The present tendency is to use computers in assoc. with synthesizers as a memory bank, capable of producing any required sounds, memorizing the composer's sequence of events, and playing the finished work whenever required. This information is fed to the computer by a teletype kbd. or special manual controller, as in certain works by Stockhausen and Boulez.