The pallophotophone was an optical sound system which could record and play back audio tracks on a strip of 35 mm black-and-white photographic film.
[2] In 1923, celebrities including Thomas Edison, Pope Pius XI, General Pershing and child star Jackie Coogan made pallophotophone recordings for later playback over the air.
Instead of beaming the light onto photographic film, the vibrating mirror reflected it directly into a photoelectric cell, generating an electronic audio signal which was amplified and used to drive the side-to-side motions of the recording stylus as it engraved a spiral groove into the rotating wax master disc.
Unlike the first-generation recorder, in these variants the tiny mirror was not vibrated directly by sound waves, but by an electromagnetic audio signal originating from a conventional microphone.
Schneiter contacted his former colleague Russ DeMuth, a mechanical engineer at GE Global Research, to help decipher the mysterious films.
Hunter, Schneiter and DeMuth studied the patents and photographs of the original pallophotophone and built a new player from scratch, using modern components, with which they were able to recover the audio from the reels.