Effects of Auditory Fatigue upon Intensity Discrimination

Abstract

Although a majority of auditory fatigue studies have utilized the TTS as the primary index of change in functioning of the auditory system, it is clear that the threshold of audibility is not a completely adequate indication of the auditory system's functional status. Indices of discrimination, for example, are not related in any systematic fashion to the threshold of audibility, since various pathological conditions of the auditory system are reflected differentially in measures of the threshold of audibility and measures of differential thresholds. In the present study changes in the intensity discrimination threshold (IDT) as well as in the threshold of audibility have been determined. Significant decreases in the IDT were found to follow fatiguing exposure, such changes being related in a negatively decelerated manner to the TTS. The extent of the change in the IDT as a function of fatigue was found to be inversely related to the SPL of the signal to be discriminated. As a result of these two relationships the range of IDT's as a function of signal strength was markedly decreased for the fatigued ear. In addition, no relationship was found between normal IDT's and size of the recording pen excursions bracketing the threshold of audibility, or in the change in the size of these two measures as a function of fatigue.