On This Day in Telephone History April 14TH 1877 Emile Berliner filed a variable-pressure transmitter caveat. Berliner discovered that the minute atmospheric vibrations due to sound waves would cause a diaphragm to vibrate, which vibrations, by varying the pressure between the point of contact between metallic electrodes, in constant contact, produced variations of electrical resistance whereby speech may be transmitted.

On This Day in Telephone History April 14TH 1877

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On This Day in Telephone History April 14TH 1877 Emile Berliner filed a Variable-Pressure Transmitter Caveat.

Berliner discovered that the minute atmospheric vibrations due to sound waves would cause a diaphragm to vibrate, which vibrations, by varying the pressure between the point of contact between metallic electrodes, in constant contact, produced variations of electrical resistance whereby speech may be transmitted.