Photoliptophone: A virtually unknown ancestor of optical audio systems to reproduce printed sound on plain paper

The Photoliptophone was a system developed by Argentinean inventor Fernando Crudo in the 1930s. The system allowed recording audio waveforms on radiographic plates, so that they could be printed on paper. The aim of the system was reducing the distribution cost of audio copies by including the printed waveforms in magazines and newspapers. The Photoliptophone obtained patents in thirty countries. National and international reports evaluating the operation of the prototype describe the Photoliptophone as a system with good audio quality. The system remained in operation for two decades, although it never managed to successfully enter the market as an alternative to mechanical recording systems. In the same period of time, a recording system known as Selenophone was developed in Austria. It used 7mm film to record audio and which could be printed on reels of paper to be later reproduced as sound. The aim of the system was to record over longer time periods than mechanical systems allowed for, as well as printing copies on paper to reduce the cost of film as physical support. This paper describes the operational principles of the Photoliptophone and compares it to the Selenophone. Original documents related to the Photoliptophone have been analyzed for this study. Such documents include patents, inventor’s personal letters, official use permits, business plans and audio waveforms printed on either paper or radiographic film. An evaluation of the audio quality of the Photoliptophone is also reported in this paper. Original printed audio waveforms that remained untouched for the last eighty years have been scanned. The associated audio was retrieved by means of numerical processing of the scanned images.