High Frequency Sound Waves 1925
SOUNDS TOO HIGH TO HEAR
SOUND-WAVES of too high a pitch to affect the ear have been produced and are likely to prove useful, we are told by an editorial writer in The Electrical World. Such waves, of course, are not sound in the strictest sense, for sound-waves are due to vibrations within the audibility range of human beings. This audibility ceases, for purely physiological reasons, at somewhere between 10,000 and 20,000 cycles per second, but there is no reason why such longitudinal vibrations of much higher frequencies could not be produced, propagated and received by means of suitable detectors. We read:
In La Revue Hydrographique for November, 1924, there is a description of complete apparatus for sending and receiving such supersound-waves under water at frequencies between 40,000 and 100,000 cycles per second. The apparatus is purely electrical, quartz and a three-electrode oscillating vacuum-tube being utilized.
Probably in time such ultra-audible waves will become of increasing scientific and practical value, and engineers should turn their attention to possible useful applications. As such, the following are within possibility: (a) Sounding of the ocean-bottom and of river-beds for geological and hydrographic purposes, navigation, laying of cables, etc.; (b) location of other vessels, icebergs, shore-line, etc., in fog or at night; (c) killing of fish, with possible extension of the method of extermination of insect pests; (d) improvement in hearing of deaf persons while the ear-drum is being agitated by ultra-audible waves; (e) extension of the range of oral communication by using supersounds as carrier waves; (f) determination of the speed of a rapidly moving object, for example, a motor-vehicle, for proving a speed law violation, etc.
Source: The Literary Digest for September 12, 1925
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