Alex Hay wanted to pick up body sounds: brain waves, muscle activity and eye  movements. Pete Kaminski, Fred Waldhauer and Cecil Coker built a battery-driven  differential amplifier which had a peak gain of 80 db from 1/2 Hz to 10 Hz. The whole  unit, batteries and all fit into a 1 by 3 by 5 inch box, no mean feat to do this in 1966. The  signal from the differential amplifier was fed into a voltage-controlled oscillator, then to a  transmitter, which sent the sound to the speakers.  
 Electrodes were placed on Alex’s head and body and all the equipment was attached to a  plastic plate fastened on Alex’s back. Here Alex is sitting in front of a television camera  and the image of his face is projected on the screen behind him as Robert Rauschenberg  
 picks up numbered cloths Alex had carefully laid on the Armory floor during the first  part of his piece.