Sound-on-disc is a class of sound film processes using a phonograph or other disc to record or play back sound in sync with a motion picture. Early sound-on-disc systems used a mechanical interlock with the movie projector, while more recent systems use timecodes.
During the 1920s and early 1930s, films in the United States were subject to censorship by state and city censor boards, which often required cuts of scenes before a film would be licensed for exhibition. While films using the sound-on-film process could accommodate a patch for a requested cut with ease, a film using sound-on-disc would require an expensive retake.[2] If the cost of compliance with a censor board was too high, the film would not be shown in that state or city.