Science on Saturday: Saving the Sonorine, an early 20th-century form of voice mail

Feb 18, 2023, 9:30 am11:00 am
Online via Zoom & in-person at PPPL
General Public



Event Description

Professor Adam Finkelstein, Princeton University

Abstract: In 1905, about two decades after Thomas Edison patented the cylinder phonograph, an affordable new device was first marketed in France that allowed people to record a one-minute voice message inscribed on a specially coated postcard, called a Sonorine, to be sent through the mail. While this technology remains largely forgotten today, Princeton University Professor Thomas Y. Levin has been amassing the largest known collection of Sonorine postcards (more than two hundred to date). The question remains, what is recorded on those cards? While a handful of the recording machines have survived, one would not want to risk using the rather crude original apparatus for playback of these recordings, for fear that it would damage the fragile surface grooves etched into the thin, century-old plaster coating on the extremely rare cards.

The goal of our project is to recover and study the audio material captured in these recordings without damaging the Sonorines themselves. This requires developing a method of "playing" the cards without in fact touching them, so we rely on a strictly optical (non-tactile) technique. Using only an off-the-shelf flatbed scanner, our method is able to reveal the unique topography of a recorded card by combining four scans at 90-degree rotations. Once aggregated into a single model, the sensitivity of these hi-resolution scans allows us to capture the "hills and dales" that encode audio in the grooves of a recorded Sonorine. We then algorithmically "unwind" the spiral and decode an audio waveform for playback. Over the course of this project, we have been able to listen to examples of these voices from the turn of the last century, to begin to decipher their words, and thereby come to an understanding of an entirely forgotten chapter of media history.

This week's SOS speaker has declined to be recorded.