ABSTRACT
We know light is able to transmit signals of audible frequencies. This is how sound recorded on the tracks of the ancient “optical sound” movies is made audible. In the photosonic process, sound is generated in a similar way, by communicating audible frequency modulations to light beams, having them pass through a rotating disk which is alternately opaque or transparent. These pulsated light beams are received by a photoelectric sensor, which transforms their variations of luminosity into variations of electric current, directly amplified by an ordinary audio amplifier connected to a speaker. The photosonic disk then works very much like a siren that uses light instead of air pressure, except that photosonic instruments are necessarily electric, needing amplification and speakers. A disk never plays the same sounds either because its sounds totally depend on the way it is played. Speed, radius, light disk distances, and the presence or absence of optical filters will dramatically shape the output timbre.
