Optical Sound Examples
The major commercial use of optical sound on film started in the late 1920s. In its simplest form, optical sound is just flickering the light from a light bulb, similar to waving a hand in front of a flashlight. The light being modulated by the recording is turned into electrical sound signals via a phototube or photodiode. Although seemingly crude, optical sound is at the core of motion picture sound and saw decades of intense research and development. From the first optical sound feature in 1927 through the stereo prints of Star Wars, over a dozen different optical sound formats have been used with incredible results. Each optical format, though, has its own unique sound attributes and challenges.
Release Formats
Variable-density
Unilateral variable-area
Bilateral variable-area
Duplex variable-area
Duo-lateral variable-area
Multi-area (35mm) / Mauer (16mm)
Mono dual-bilateral variable-area
Stereo dual-bilateral variable-area
Studio Tracks
Wester Electric Licensed Equiptment
Push-pull variable-density 100mil
Push-pull variable-density 200mil
ERPI push-pull variable-area 200mil
Push-pull variable-density offset 200mil
RCA Photophone Licensed Equipment
Push-pull variable-area
Class A
Push-pull variable-area
Class B
Push-pull variable-area
Class AB
Push-pull variable-area
Class A direct positive