Hearing by Electricity

Radio Record, Volume III, Issue 30, 7 February 1930, Page 6

Hearing by Electricity

Demonstration in New York Y hearing with an eardrum vibrated by electricity, instead of by sound waves, a man in New York recently listened to music inaudible to other members of the audience witnessing the demonstration. The inventor was electrically connected to a powerful audiofrequency amplifier, and when he placed a finger tip against one ear of a member of the audience, using a sheet of paper as insulation, the effect was to produce a condenser type loudspeaker y | with the finger tip as one pole and the eardrum and surrounding flesh as the other. This vibrated the drum of the stopped-up ear just as though sound waves were reaching it. The experiment, which appears to have no practical value at present, demonstrated a novel way in which sound may be directly transmitted to the eardrums other than ‘by ordinary sound waves. Every sound ordinarily heard, from the humming of a gnat to the crashing of thunder, reaches the ear through vibrations of gases or solid substances. Light, heat, and radio waves pass through the ether. Sound waves cannot travel through a vacuum. They require gases or solid substances as a medium of travel. Vibrations that create sound are produced mechanically in several ways. In the phonograph, the needle, following the up-and-down or the side-to-side waves in the groove on the recor, 1, moves the diaphragm of the insiTtment. In the telephone the diaphragm of the receiver is vibrated by electrical impulses coming over the wire. In talking pictures, light and dark bands on the film allow varying amounts of light to reach a photo-electric cell. This transforms the variations of light intensity into électrical impulses which move a diaphragm as in a telephone.. One of the latest uses for the last method was also demonstrated recently in the form of an instrument that makes audible the numbers called on a dial telephone. When a number is dialed the operator hears it announced vocally. Small reels of talking film containy~ .a voice record of the numerical units from zero to ten. These reels turn automatically to the numbers corresponding to those dialed by the calk . ° By a mechanism similar to that used in talking movies the numbers are made audible.