Meaning of thermophone | Babel Free

Definitions

1. A form of transducer that generates sound waves of precise power.
2. A portable telethermometer, using a telephone in connection with a differential thermometer.
   historical
3. A telephone involving heat effects, as changes in temperature (hence in length) due to pulsations of the line current in a fine wire connected with the receiver diaphragm.
   historical

CEFR level