The telephone

An account of experiments connecting speech acoustics and electricity, beginning with investigations into the vocal mechanism and vowel pitch that revealed resonances of mouth and pharynx, followed by study of Helmholtz’s work and attempts to reproduce his synthesis of vowel tones. The author describes inventing electrically driven tuning-forks and conceiving a multiplexing scheme whereby different pitches sent over a single wire would be received by matching electromagnets, outlines practical telephony experiments and the varieties of electrical currents and apparatus that produce audible sounds, and traces the development from musical-electrical ideas to methods for transmitting speech electrically.