INART 55

History of Electroacoustic Music

Polytopes and CEMAMu


In 1967, Iannis Xenakis took a position as Professor of Music at Indiana University at Bloomington. While his heart did not lie in teaching, he took the job due to its potential for realizing a research center in mathematics and music. The center, however, was not to be, as funding for higher education was increasingly diverted to the Vietnam War. The added stress of being away from his family, who remained in Paris, also took its toll, and he resigned in 1972.

In the meantime, he embarked on a series of multi-media, site-specific works that he called polytopes (poly = many; tope = place), to refer to large-scale performances involving compositions of sound and light. His first polytope was at the French Pavilion at the Montreal Expo of 1967 (the building remains intact, today housing the Casino de Montreal). The pavilion had a large central space, through which a series of steel cables went from floor to ceiling. Five networks of cables outlined curved geometrical shapes. The cables had 1200 flash bulbs that were triggered in a pattern that reflected changes in the music, although the light and music were not directly synchronized. The music was written for four instrumental ensembles, and was played through a series of loudspeakers.


The next polytope occurred outdoors at the Shiraz Festival of Arts and Music in Iran in 1971, at the ruins of Persepolis. An array of 59 loudspeakers played an eight-channel musique concrète score, while 92 spotlights and 2 lasers were directed at the sky and at the hills in the distance that contained the tombs of the classical heroes Darius II and Artaxerxes. There, bonfires could be seen burning, and constantly changing light patterns were created on the hills by processions of torch-bearing children walking up the hillsides.

Le Diatope was created for the inauguration of Paris' Pompidou Centre in 1978. Xenakis also was able to design the space for this work, which at a glance bears some resemblance to the Philips Pavilion. Like the Polytope de Cluny, Le Diatope also featured strobe lights, colored lasers and programmable mirrors. But this was on a larger scale, with more of them, a longer musical work, and a light program that was updated every 1/25 of a second.

In 1972, after leaving his position at the University of Indiana at Bloomington, Xenakis began his next polytope in Paris at the Roman Baths of Cluny. This was digitally controlled, with a computer determining the operations of 600 strobe and three colored lasers that were projected on the walls and enhanced by 400 adjustable mirrors. The lights created patterns such as circles, spirals, arcs, and emulations of natural phenomena such as rivers, galaxies, or northern lights. The lasers were made to reflect off of the mirrors. Since the laser beams can be reflected without losing any intensity, they were reflected multiple times from a succession of mirrors, forming sharp outlines that traced shapes around the flashing lights. The music was on an eight track tape, occupying seven channels, with channel eight containing control signals for the lights and mirrors. The music featured electronic sounds created with computer-generated stochastic algorithms.

That same year Xenakis formed CEMAMu (Centre d'Etudes de Mathematiques et Automatiques Musicales/Center for Studies in Mathematics and Automated Music) just outside of Paris. With funding from the French Ministry of Culture, he was able to create UPIC (Unite Polyagogique Informatique du CEMAMu), a computer drawing system that allowed shapes to be drawn on a tablet and be mapped to musical parameters. This represented an expansion of the designs that were the basis of sections in his earlier works Metastaseis and Pithoprakta. A graphic shape, or arc, could represent any aspect of a musical sound or event; up to 4000 arcs could be drawn on a single page, and a page could be played forward, backward, at various speeds.


Graphic UPIC score to Mycenae-Alpha
5'16" - 7'16"

Among the pieces he created with UPIC was Mycenae-Alpha in 1978, created for the Polytope de Mycenes in Greece. Mycenae-Alpha was an interlude to be played between the main pieces at the site. The performance also included searchlights shining into the sky and torches on neighboring mountains, as in earlier polytopes. This was a significant project for Xenakis on a personal level, as it was the first time he was able to return to his homeland Greece since he had become a fugitive after World Was II.

The UPIC system was used by a number of composers, and was a popular field trip for classes school children. Xenakis was committed to introducing new approaches for the use of computers in teaching, and enjoyed demonstrating the system for children who then created their own pieces.