This movie flyer is from California's first drive-in theater which opened on September 9, 1934. This drive-in would eventually be called the Pico Drive-in Theater named after the streets it was built by. The Pico Drive-in was just the 4th drive-in theater to be built! The Weymouth Drive-In Theatre in Weymouth, Massachusetts was the 5th drive-in and wasn't even opened until May 6, 1936. So this flyer is extremely rare having been printed well before the 5th drive-in theater was ever constructed. Eventually almost 5,000 drive-ins would be built nationwide.
As with most early drive-in theaters, the speaker system that was used was mainly two or three large speakers mounted at or near the screen tower. The sound was then, "blasted," back at the cars on the theater lot. This of course would anger nearby neighbors because the sound would travel for sometimes miles. Because of the sound system that was in place at the time, local ordinances were changed to force the Pico Drive-in theater to comply with how sound would be contained at the drive-in.
The movie flyer below is dated June 30, 1935 and announces the "New Individual Sound Sensation," starting on July 1, 1935. When reading the flyer below, note the explanation given for the new sound system. Also note that the price of the movie was just 30¢ with reduced admission for children.