Recreating The RCA Photophone

The pallophotophone was an early audio recorder created by GE researcher Charles Hoxie (seated in the photo) in 1922. Rather than using magnetic wire or lacquer disks, the device captured audio waveforms on sprocketless 35 mm film as a series of 12 parallel tracks reflected from a vibrating mirror. It was used to record some of the world's oldest surviving radio broadcasts on Schenectady, New York radio station WGY between 1929 and 1931.

The machine -- eventually branded the RCA Photophone -- failed to catch on, in part because 35 mm film was expensive and required time-consuming photographic processing before it could be played back. The device lost out to competing technologies and was eventually abandoned.

However, a small collection of Photophone film canisters survived in the basement of the Schenectady Museum. The only clue to their contents were handwritten notes on the cans identifying them as radio programs from the 1920s. They remained shelved and forgotten until rediscovered by the museum's curator, Chris Hunter. He was intrigued, but there was no way to replay the material using modern equipment.

Luckily, Hunter was introduced to Russ DeMuth, a GE engineer, who rose to the challenge and built a modern version of the pallophotophone based upon Charles Hoxie's original design sketches. After considerable effort, DeMuth was able to retrieve the long-forgotten sound from the films. The recordings include Thomas Edison, Herbert Hoover and Henry Ford at the “Edison Light’s Golden Jubilee,” broadcast in October, 1929, and perhaps the oldest known recording of the NBC chimes.

Let's hope the Schenectady Museum creates an online exhibit that allows people from around the world to experience these 80 year-old recordings in all their dusty glory.

Edison speaks! Cracking the pallophotophone code [thanks, Neural Gourmet!]