Auditory Pain Thresholds for Intermittent,“Beat” and Steady Signals

Abstract

Eight Ss were given audiograms and ear examinations to insure normality and then presented with a series of tones at either 1000 cps or 2500 cps. For each frequency the sounds were presented as constant tones, as interrupted pulses, or as “beats,” the pulses and beats being given at repetition rates of either 3, 6, or 15 per sec. For each condition the intensity of the sound was increased by a series of steps. S was to indicate when the tone was “just noticeably unpleasant” (JNU) and when it was “just noticeably painful” (JNP). These thresholds were measured in terms of the db attenuation from a given maximum of 130 ± 2 db. It was found that individual pain thresholds varied from about 100 db to over 130 db, with unpleasantness thresholds about 8 to 10 db below pain thresholds. The 2500-cps signal, irrespective of whether it is presented as a steady stimulus, a series of pulses, or a series of beats, is reacted to as “unpleasant” or as “painful” at a slightly, but consistently lower intensity level than the corresponding 1000-cps tone. At each frequency used, intermittent tones are judged as “unpleasant” or “painful” at lower intensity levels than steady tones. The differences are slight but consistent. Repetition rates of three pulses or beats per second were fairly consistently found to have a lower unpleasantness and pain threshold than either 6 or 15 per sec. In general, pain thresholds seemed to be related primarily to power per pulse, rather than total energy in a series of pulses.