Wiktionary
pallophotophone
n. A device that records sounds on photography film.
Wikipedia
Pallophotophone
The pallophotophone was a photographic sound recording and playback system developed by General Electric researcher Charles A. Hoxie circa 1922. Hoxie created its name from the Greek words for "shaking light sound". The RCA Photophone sound-on-film system for motion pictures was later derived from it.