History of Sound Recording - Recording On Film

Recording On Film

The first attempts to record sound to an optical medium occurred around 1900. In 1906 Lauste applied for a patent to record sound on film, but was ahead of his time. In 1923 Lee de Forest applied for a patent to record to film; he also made a number of short experimental films, mostly of vaudeville performers. William Fox began releasing sound-on-film newsreels in 1926, the same year that Warner Brothers released Don Juan with music and sound effects recorded on discs, as well as a series of short films with fully synchronized sound on discs. In 1927 the sound film The Jazz Singer was released; while not the first sound film, it made a tremendous hit and made the public and the film industry realize that sound film was more than a mere novelty.

The Jazz Singer used a process called Vitaphone, a process that involved synchronizing the projected film to sound recorded on disk. It essentially amounted to playing a phonograph record, but one that was recorded with the best electronic technology of the time. Audiences used to acoustic phonographs and recordings would, in the theatre, have heard something resembling 1950s "high fidelity."

In the days of analog technology, however, no process involving a separate disk could hold synchronization precisely or reliably. Vitaphone was quickly supplanted by technologies which recorded a sound track optically directly onto the side of the strip of motion picture film. This was the dominant technology from the 1930s through the 1960s and is still in use as of 2004.

There are two types of synchronised film soundtrack, optical and magnetic. Optical sound tracks are visual renditions of sound wave forms and provide sound through a light beam and optical sensor within the projector. Magnetic sound tracks are essentially the same as used in conventional analog tape recording.

Magnetic soundtracks can be joined with the moving image but it creates an abrupt discontinuity because of the offset of the audio track relative to the picture. Whether optical or magnetic, the audio pickup must be located several inches ahead of the projection lamp, shutter and drive sprockets. There is usually a flywheel as well to smooth out the film motion to eliminate the flutter that would otherwise result from the pull-down mechanism. If you have films with a magnetic track, you should keep them away from strong magnetic sources, such as televisions. These can weaken or wipe the magnetic sound signal. Magnetic sound on an acetate base is also more prone to vinegar syndrome than a film with just the image.

For optical recording on film there are two methods utilized. Variable density recording uses changes in the darkness of the soundtrack side of the film to represent the soundwave. Variable area recording uses changes in the width of a dark strip to represent the soundwave.

In both cases light that is sent through the part of the film that corresponds to the soundtrack changes in intensity, proportional to the original sound, and that light is not projected on the screen but converted into an electrical signal by a light sensitive device.

Optical soundtracks are prone to the same sorts of degradation that affect the picture: e.g. scratches, copying.

Unlike the film image that creates the illusion of continuity, sound tracks are continuous. This means that if film with a combined soundtrack is cut and spliced, the image will cut cleanly but the sound track will most likely produce a cracking sound. Fingerprints on the film may also produce cracking or interference.

In the late 1950s the cinema industry, desperate to provide a theatre experience that would be overwhelmingly superior to television, introduced wide-screen processes such as Cinerama, Todd-AO, and CinemaScope. These processes at the same time introduced technical improvements in sound, generally involving the use of multitrack magnetic sound, recorded on an oxide stripe laminated onto the film. In subsequent decades, a gradual evolution occurred with more and more theatres installing various forms of magnetic-sound equipment.

In the 1990s, digital systems were introduced and began to prevail. In many of them the sound recording is, as in Vitaphone, again recorded on a separate disk; but now, digital processes can achieve reliable and perfect synchronization.