from The Century Dictionary.
- noun An instrument having the functions of both an ear-trumpet and a speaking-trumpet.
- noun An apparatus invented by Edison for increasing the intensity (amplitude) of sound-waves, as those from spoken words.
from the GNU version of the Collaborative International Dictionary of English.
- noun A form of combined speaking and ear trumpet.
- noun An instrument, proposed by Edison, for greatly intensifying speech. It consists of a phonograph diaphragm so arranged that its action opens and closes valves, producing synchronous air blasts sufficient to operate a larger diaphragm with greater amplitude of vibration.
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