";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.
directional photocells aimed at the stage lights, so that the dancers triggered sounds as
they cut the light beams with their movements. and a series of antennae.
When a dancer came within four feet of an antenna a sound would result.
Cage, Tudor, and Gordon Mumma operate equipment to modify and determine
the final sounds." -from mediaartnet.