5 Sound-on-Film: An Art of Time

The appearance of optical sound on film marks a fundamental change in sound-film technology. While precursors to optical sound technology can be traced back to the nineteenth century, the most important developments were made after World War I: prominent early examples are Lee DeForest’s Phonofilm in the United States and the Tri-Ergon system in Germany.^[19] In around 1930, in the course of the conversion of film production and cinemas to the sound film, optical sound asserted itself over needle sound and is used to this day. During the optical sound process, a microphone transforms the barometric fluctuations of the sound into current fluctuations, which in turn modulate a light source enabling the sound to be exposed onto the same medium as the images, the film, as changing optical density. During playback, a light-sensitive component, a photocell, then scans this graphic sound film copied onto the soundtrack of the film and in turn transforms it into current fluctuations that are played back by loudspeakers. While in the older synchronized sound systems mediation had to take place between the movements of the sound and image equipment, the synchrony of optical sound — at least during the showing — is essentially based on the conversion and transmission of sound signals over several entities. A central component of this dematerialization of sound into signal transmission and storage chains are the amplifier tubes developed by DeForest and Robert von Lieben (both 1906).^[20]

The consequence of the incompatibility of the intermittent motion of the image track and the continuous motion of the soundtrack is noticeable in the shifting of the sound to the position of the image on the film by approximately one second. Thus, the film can be transported continuously through one part of the projection device and discontinuously through another and nonetheless be played back simultaneously. Due to the fixed assignment on the film’s surface, using optical sound results in a technical synchrony that is largely independent of the randomness of the respective projection situation. What is more, the optical sound strip (without images) enables cutting and assembling, thus a manipulation of time according to the image editing model, which with needle sound would only be possible through a relatively large amount of effort.^[21] With the comprehensive standardization and technical stabilization of the film speed as a result of the conversion to sound film, the length of the film is associated with a prescribed space of time. Film is no longer measured in meters but in minutes and seconds as the range for images and sounds.^[22] In short: synchronous sound turns the cinema into an art of time.^[23]

Optical sound — at least historically — constitutes the medium of technical and esthetic practices of temporal sound-image coordination that fanned out with the conversion to sound film and subsequent discourses: from the clapperboard to motorized sound-film editing tables, and from asynchronism^[24] to Mickey Mousing. The cartoon Steamboat Willie (1928) by Walt Disney, for example, very early on developed certain aspects of this medium in both a practical as well as a thematic respect.