Relation between Loudness and Duration of Tonal Pulses. III. Response in Cases of Abnormal Loudness Function

Abstract

Previously determined relations between time-threshold and loudness were investigated in humans with abnormal loudness response. The following principles concerning the nature of the altered function were established in pathologic cases with complete recruitment by time-threshold measurement and by binaural loudness matching: (1) at a constant level above threshold, the hearing loss in db is related to the log. of the pathologic degree of loudness increment as determined by L/I values; (2) for a given hearing loss, the L/I value of the loudness-increment degree decreases linearly with the logarithmic increase of the level above threshold; (3) the graphic results of time-threshold determination appear directly continuous with those of loudness matching. Experimentally induced abnormal loudness response under conditions of masking confirms the results. In cases of mixed impairment, with incomplete recruitment, the receptive component of hearing loss can be determined in dbs from the measured degree of loudness increment. The results of such determinations are similar to those obtained by bone-conduction measurements. The significance of time-threshold determinations and the limitations in their practical applicability for loudness measurements are discussed.