The early "talkie" movies had the movie soundtrack pressed on to 16" diameter records that were played at 33 1/3 rpm on a turntable that was synchronized with the film projector. Each side has the soundtrack for one reel. The movie was originally issued with sound on film that could be played at theaters with the expensive new projectors capable of reproducing the sound from the film. However, many theaters still had the old style sound on disc machines, so the sound track was dubbed to these 16" discs to be played in sync with the movie. Below are pictures of the soundtrack discs for the 1931 movie "ALOHA" by Rogell Productions, Ltd and released thru Tiffany Productions. The disc were pressed by Columbia. Here is most of a soundtrack for the movie ALOHA made in 1931 recorded from a set of 16" movie discs. Unfortunately, I am missing the disc with reels 2 & 4. In the South Seas, a half-caste island girl refuses to follow tradition and marry a fellow islander, instead falling in love with a white man and heir to an American fortune."
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LISTEN	Reverse of Reel 9 Disc