The Variophone was an optical synthesizer that utilized sound waves cut onto cardboard disks rotating synchronously with a moving 35mm movie film while being photographed onto it to produce a continuous soundtrack.
The first artificial soundtrack ever created was drawn in 1930 by composer and musical theorist Arseny Avraamov who was working with a hand-drawn technique for producing sound effects.
Many sound films and artificial soundtracks for movies and cartoons were produced by means of the Variophone, including the popular sound-films, often broadcast in 1930-1940s Symphony of the Piece and Torreodor.
Documentation for the Variophones was transferred to the Acoustical Laboratory at Moscow State Conservatory and later, to the Theremin Center.
In 2007, several hours of graphical soundtracks produced with the Variophone were discovered in a Moscow film archive and await publishing.