John Cage made Variations V in 1965 for the Merce Cunningham Dance Company. He  and David Tudor settled on two systems for the sound to be affected by movement. For  the first, my colleagues and I set up a system of directional photocells aimed at the stage  lights, so that the dancers triggered sounds as they cut the light beams with their  movements. A second system used a series of antennas. When a dancer came within four  feet of an antenna a sound would result. Ten photocells were wired to activate tape recorders and short-wave radios. Cecil Coker designed a control circuit, which was built  by my assistant Witt Wittnebert. Film footage by Stan VanDerBeek and Nam June Paik’s  manipulated television images were projected on screens behind the dancers. In this  photograph Variations V is performed for a television taping session in Hamburg. The  photocells were located at the base of the five-foot antennas placed around the stage.  Cage, Tudor, and Gordon Mumma operate equipment to modify and determine the final  sounds.