The phonomotor or "vocal engine" was a device invented by

Thomas Edison Thomas Alva Edison (February11, 1847October18, 1931) was an American inventor and businessman. He developed many devices in fields such as electric power generation, mass communication, sound recording, and motion pictures. These inventions, ...

in 1878 to measure the mechanical force of sound. It converted

sound energy In physics, sound energy is a form of energy that can be heard by living things. Only those waves that have a frequency of 20 Hz to 20 kHz are audible to humans. However, this range is an average and will slightly change from individual t ...

sound power Sound power or acoustic power is the rate at which sound energy is emitted, reflected, Acoustic transmission, transmitted or received, per unit time. It is defined as "through a surface, the product of the sound pressure, and the component of the ...

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 A phonograph, later called a gramophone, and since the 1940s a record player, or more recently a turntable, is a device for the mechanical and analogue reproduction of sound. The sound vibration Waveform, waveforms are recorded as correspond ...

Operation

Sound waves entering a mouthpiece and falling on a diaphragm were conveyed by a piece of rubber tubing and a spring to a pawl, which vibrated against a very fine-toothed ratchet wheel. The diaphragm and mouthpiece were similar to those used on the phonograph. Vibrations caused by the voice caused a shaft and flywheel to rotate. Steady pressure from breath produced no motion, but some voices could produce rapid motion. The speed of rotation depended on the pitch of the sound. It was able to operate a small drill or saw which could bore or cut wood. When a long sustained sound got the flywheel up to an appreciable speed, considerable force was required to stop it.

Impact

The Chicago Tribune in May 1878 predicted that it would be the basis for sound powered toys such as dolls which bow when spoken to, though none are known to have been marketed. Edison described it as a scientific toy. A U.S patent application was filed for the "Vocal Engine" in 1878, and a patent was granted on December 10 of that year. An 1884 ''

Nature Nature is an inherent character or constitution, particularly of the Ecosphere (planetary), ecosphere or the universe as a whole. In this general sense nature refers to the Scientific law, laws, elements and phenomenon, phenomena of the physic ...

'' article on sound mills, similar devices to the phonomotor, reported that Edison's device, "literally accomplished the feat of talking a hole through a deal board." A restored model of the phonomotor is in the Edison Menlo Park laboratory exhibit at the Greenfield Village Museum in

Dearborn, Michigan Dearborn is a city in Wayne County, Michigan, Wayne County in the U.S. state of Michigan. An inner-ring Metro Detroit, suburb of Detroit, Dearborn borders Detroit to the south and west, roughly west of downtown Detroit. In the 2020 United States ...

, and was exhibited in operation for visitors in the 1930s.
Jehl, Francis, "Menlo Park Reminiscences, Part 1," originally published by The Edison Institute, Greenfield Village Museum, 1936. Reprint by Kessinger Publishing, LLC (2002) page 181.. Retrieved October 29, 2010

References

External links

* T.A. Edison,
"Vocal Engine"
US Patent 210,767, Patented December 10, 1878. {{Thomas Edison Thomas Edison Audiovisual introductions in 1878 Sound measurements 19th-century inventions American inventions