Audiometer
or AUDIMETER, an instrument devised by Professor Hughes, the inventor of the microphone. Originally its object was to measure with precision the sense of hearing. Among its constituent parts are an induction coil, a microphone key and a telephone. The audiometer has been materially modified, and is now principally used for obtaining a balance of induction from two electric coils acting upon a third one. A scale is provided to show the extent of the movement.