Another early voice effect using the same principle of the throat as a filter was the Sonovox. Instead of a throat microphone modulating a guitar signal, it used small loudspeakers attached to the performer's throat.Found at Uncertain Times.
It was used in films such as A Letter to Three Wives (1949), The Secret Life of Walter Mitty (1947), the voice of Casey Junior the train in Dumbo (1941) and The Reluctant Dragon (1941), the instruments in Rusty in Orchestraville, the piano in Sparky's Magic Piano, and the airplane in Whizzer The Talking Airplane (1947).
The Sonovox was also used in many radio station IDs produced by PAMS of Dallas and JAM Creative Productions. Lucille Ball made one of her earliest film appearances during the 1930s in a Pathé Newsreel demonstrating the Sonovox.