The soundman (1950)

This short on movie sound men starts with a short history of sound in the movies. We then see how the different jobs in the sound department contribute to the finished film. They start with the technicians, who record the original sounds, and end with the re-recording mixer who takes several different tracks and blends them into a single soundtrack. Preserved by the Academy Film Archive in partnership with Library of Congress Motion Picture, Broadcasting, and Recorded Sound Division in 2012.