Photoelectric sound generation
The photoelectric sound production is a kind of sound production, which is the photoelectric effect takes advantage. The light from a light source hits a photocell through a screen . This photocell generates a voltage that depends on the intensity of the light radiation. These voltage changes can be made audible via an amplifier and a loudspeaker. This technique was of some importance in the development of electronic music and sound film .
The "super piano"
Emerich Spielmann developed his so-called “Superpiano” in 1928, which systematically used photoelectric sound generation for the first time. In doing so, he placed rotating disks containing transparent holes between the light source and the photocell. Depending on the speed of the discs and the number of holes, the resulting alternating voltage changed. For each of the twelve notes of the chromatic scale , the super piano required a separate disc. The operation took place via a keyboard . The brightness of the light source changed with the strength of the keystroke, so that dynamic differences were possible as with a normal piano. Because of the complicated construction - since the discs were operated by a single motor, a separate gear ratio was necessary for each one - the "Superpiano" never went into series production. The optical sound organ developed by Edwin Welte was more successful in the 1930s .
The optical tone method
The development of photoelectric sound generation also made the optical sound process possible . When recording film material, the opposite approach is initially chosen: sound vibrations are converted into changes in light intensity, which are recorded on the film next to the image. When the film is played back, these light fluctuations are then translated into sound vibrations using the method described above. This technique played an important role in the development of the sound film.
literature
- André Ruschkowski: Electronic sounds and musical discoveries , Reclam, Stuttgart, 1998, ISBN 3-15-009663-4
- Peter Donhauser: Electrical sound machines , Böhlau, Vienna, 2007