Abstract:

The present study assesses the ability of four listeners with high-frequency, bilateral symmetrical sensorineural hearing loss to perform horizontal localization of a click train in the presence of a white noise masker. The speaker array and stimuli are identical to those described in the preceding abstract. The localization performance of hearing-impaired listeners is inferior to that of normal-hearing listeners in all conditions. Both groups of listeners show the same pattern of performance when noise is presented straight ahead: Performance is not affected by noise when the signal-to-noise ratio (S/N) is greater than 0 dB; below this value, performance degrades when S/N decreases. When noise is presented at the side, the performance of impaired listeners starts to worsen at higher S/N's (6 to 12-dB S/N) than normal-hearing listeners and reaches a lower level. The normal-hearing listeners in the low-pass conditions reproduce the general form of the effects of noise on hearing-impaired listeners, but not the absolute level of performance. Parallel measures of clicks detectability are available to assess the extent to which audibility is responsible for the lower absolute level of performance observed in impaired listeners.