thermophone

== English == === Etymology === From thermo- +‎ -phone. === Noun === thermophone (plural thermophones) A form of transducer that generates sound waves of precise power. (historical) A portable telethermometer, using a telephone in connection with a differential thermometer. (historical) 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.