What is "phonomotor"

Phonomotor \Pho`no*mo"tor\, n. [Phono- + -motor.] (Physics) An instrument in which motion is produced by the vibrations of a sounding body.

n. (context physics English) An instrument in which motion is produced by the vibrations of a sounding body.

The phonomotor or "vocal engine" was a device invented by Thomas Edison in 1878 to measure the mechanical force of sound. It converted sound energy or sound power into rotary motion which could drive a machine such as a small saw or drill. It derived from his work on the telephone and phonograph.