I came across an interesting article from the December 1928 issue of Popular Mechanics. It goes into some amount of detail into the movie industry at the time. They make reference to Orthophonic records used for the movie soundtrack. In additional, an exponential horn is shown on one page of the article.
I attached a pdf that contains the entire article.
Enjoy,
Kevin

The purchase of a Genuine Victrola closes the Avenue of Future Regret.
- ANNOUNCEMENT The Victrola Shortage Today (New Castle News, Friday, December, 20, 1918)