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Optical sound
A system in which the photographic (optical) sound track on a film is scanned by a horizontal slit beam of light that modulates a photoelectric cell. The voltages generated by the cell produce audio signals that are amplified to operate screen speakers.
A sound track in which the sound record that takes the form of density, or area, variations in a photographic image. An optical recorder or sound camera transfers sound to an optical image.
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The main advantage of optical sound is that it can be printed on the same film at the same time as the picture. By contrast magnetic film requires a separate process. This process is now supplemented by digital, which also prints onto the same film.
The National Film and Sound Archive of Australia acknowledges Australia’s Aboriginal and Torres Strait Islander peoples as the Traditional Custodians of the land on which we work and live and gives respect to their Elders both past and present.