Differential Sensitivity to Duration of Acoustic Signals

Experiments were conducted to assess differential sensitivity to acoustic signal duration under various combinations of reference duration, sensation level, and signal frequency, and to determine whether hearing impairment, ostensibly due to cochlear pathology, affects such discrimination. The absolute DL (difference limen) was linear as a function of reference duration at both 10 dB and 50 dB sensation levels in normal subjects and in those with presumed cochlear pathology. When a 10 dB SL signal was used, the mean absolute DL increased at the rate of 2.63 msec per 100-msec increase in reference duration. A concomitant increase of 2.38 msec per 100-msec increase in reference duration was observed when a 50 db SL signal was employed. Neither the signal frequency nor the presence of sensorineural hearing loss affected the duration DL, whereas a sensation level effect was exhibited by both types of subject. A smaller limen was obtained at 50 dB SL than at 10 dB SL.