Phonodeik
From Ccpi
The phonodeik is an instrument designed by Dayton Clarence Miller to photographically record the shape of complex sound waves more precisely than previously possible. Sound waves are collected in a resonator horn, on one end of which is attached a thin mica or glass diaphragm. This is connected by wire to a fixed spring. The wire is wrapped once around a spindle, on which is attached a mirror, its surface perpendicular to the axis of the spindle. As sound waves cause the diaphragm to oscillate, the wire rotates the spindle, tilting the plane of the mirror. A focused beam of light, reflected off the mirror's surface, can then trace out the diaphragm's oscillations onto photographic film.
More advanced versions of this device added the ability to project the tracer onto a screen for demonstration purposes.
The name phonodeik, "to show sound", was suggested in December 1909 by Edward W. Morley of the Case School of Applied Sciences, during an American Physical Society (APS) meeting in Boston.
