rca means radio corporation of America it was founded in 1919 it was taken over by General electric co. in 1986 its most notable projects were the infamous gramaphone, Rca photophone, Rca televisions.

Sound-on-film has existed since 1927, but it has only been in a digital format since around 1992. Disney films created before then (like all other sound films) recorded the sound effects and music on analog media. It was synchronized onto the film strips using either magnetic (just like a cassette tape) or optical (usually the RCA Photophone) formats. Most 35mm films still include an RCA Photophone track, in case the theater is not equipped to run digital sound or the digital equipment fails.

the photophone

He invented the telephone, the photophone, and the original audiometer.