The technology of synthesizing sound from light is a curious combination of research from the realms of mathematics, physics, electronics and communications theory which found realization in the industries of motion picture films, music, surveillance technology and finally digital communications. As such, it's history is an interesting cross section of 20th century history, reaching from the euphoria of the late 19th Century and early 20th Century inventors (who often struggled between "scientific" and "supernatural" explainations of their work) through the paradigm-smashing experiments of the Soviet avant-garde in the 1920's and 1930's to the cynical clash of ideologies of the Post-war years and finally to the dawn of the digital era in the 1970's.
This history has its fair share of eccentric and fascinating characters, such as Lev Theremin, Arseny Abraamov and Daphne Oram--the first woman to create and run a sound studio, as well as the first woman to "design and build an entirely new sound recording medium" (Jo Hutton in Organized Sound). There is quite a bit of work left to do, particularly in recognizing and translating the legacies of the Russian avant-garde artists such as Boris Yankovsky, Evgeny Scholpo, Nikolai Voinov and the forementioned Abraamov, whose works are largely unknown outside the former Soviet Union. A forthcoming article on "Russian Graphical Sound" for the Computer Music Journal by Andrei Smirnov could be one of the biggest English-language breakthroughs in this area.
Quite clearly, the connection with filmmaking is very close. Optical sound technology was developed first solely for recording soundtracks for early "speakies", and every one of the Russian innovators used their graphical sound techniques to provide music scores for the kino. But the connection with the "Visual Music" movement in cinema is also very close, with perhaps the works of Norman McLaren providing the strongest bridge. But the "direct cinema" techniques of many filmmakers from the 1920's and 1930's on through the 1960's and 1970's show more than a casual relationship with the techniques of direct optical sound synthesis. The works of Oskar Fischinger, Len Lye, Stan Brakhage, John Whitney, Hy Hirsch, Harry Smith, Jordan Belson, Larry Cuba and many others all reflect an ongoing lineage of this "visual music" tradition. (The "Kinetica" screening programs, available from the iotaCenter of Los Angeles, provide the most comprehensive overview of this fascinating film history, and the Visual Music website gives an excellent synopsis and timeline as well.)