Some experiments have been conducted to determine the effect of intense high frequency airborne sound on mice and a variety of insects. The sound source was a high frequency siren. The frequency used was about 20 kc, and its acoustic level, in the region where the subjects were placed, was between 160 and 165 db (relative to 10−16 watt/cm2). With sufficient exposure—from 10 seconds for flies and mosquitoes to 3 or 4 minutes for roaches and caterpillars—the sound proved lethal in all cases. More detailed work was performed on mice and the roach, Periplaneta americana. In both cases it was definitely established that the heating produced by sound absorption was sufficient to cause death. In addition to the heating there are other effects, notably tissue rupture, as evidenced by the almost complete distruction of the wings on flies and mosquitoes and the rapid deterioration and final disappearance of the external pinna of a mouse who had received a sublethal dose. During observations it has been impossible to completely avoid personal exposure to the sound field, and some of the effects observed under these conditions will be described. These included momentary dizziness, and heating of exposed parts of the hand.

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