Description courtesy Monoskop:

9 Evenings: Theatre and Engineering was conjured up by Robert Rauschenberg and Billy Klüver and was originally intended to be presented as part of the Stockholm Festival of Art and Technology in 1966. But when the festival’s negotiations fell through, Billy Klüver moved the event to the 69th Regiment Armory and called it 9 Evenings: Theatre and Engineering. The participants consisted of 10 artists and some 30 engineers to create a blend of avant-garde theatre, dance and new technologies.

9 Evenings was the first large-scale collaboration between artists and engineers and scientists. The two groups worked together for 10 months to develop technical equipment and systems that were used as an integral part of the artists’ performances. Their collaboration produced many “firsts” in the use of new technology for the theater, both with specially-designed systems and equipment and with innovative use of existing equipment. Closed-circuit television and television projection was used on stage for the first time; a fiber-optics camera picked up objects in a performer’s pocket; an infrared television camera captured action in total darkness; a Doppler sonar device translated movement into sound; and portable wireless FM transmitters and amplifiers transmitted speech and body sounds to Armory loudspeakers.

Artists involved with 9 Evenings include: John Cage, Lucinda Childs, Öyvind Fahlström, Alex Hay, Deborah Hay, Steve Paxton, Yvonne Rainer, Robert Rauschenberg, David Tudor, and Robert Whitman.