Clinical Measurement of Temporal Auditory Summation

Abstract

The psychophysical tracking method utilizing a conventional Bekesy audiometer was evaluated as a clinical procedure for measuring temporal auditory summation at the threshold of audibility. It was determined that a number of procedural restraints, involving the relation between the physical parameters of short-duration tones and the psychophysiological operating characteristics of the auditory system, must be observed in order to obtain meaningful results on normal and hearing-impaired listeners. When these restraints are observed, measurement of temporal auditory summation at the threshold of audibility was shown to be a feasible clinical procedure requiring only six minutes to perform. A qualitative screening technique was developed that agreed well with subsequent quantitative determinations of complete temporal summation functions. Results obtained from a listener with normal hearing in one ear and a moderate sensorineural hearing loss in his contralateral ear revealed that while the conventional analysis of threshold-duration functions is appropriate for listeners with normal hearing, it does not seem appropriate for the hearing-impaired listener. Because of this, a revised method of analysis for threshold-duration functions is proposed that appears appropriate for both normal and hearing-impaired listeners. Further analysis of the results on this listener showed that the normal and deviant results which were obtained are consistent with the fundamental theory of temporal auditory summation. They also suggest that threshold-duration functions may be a more sensitive index of a physiological disturbance at the level of the cochlea than the present direct and indirect measures of loudness recruitment.