Impaired auditory functions underlying degraded speech perception in noise

Hearing-impaired people often experience great dif culty with speech communication when background noise is present. In most cases, the problem persists even if reduced audibility has been compensated for by hearing aids. Clearly, other impairment factors besides reduced audibility must be involved. In order to minimize confounding effects, the subjects participating in this study consisted of groups with homogeneous, symmetric audiograms. The perceptual listening experiments assessed the speech intelligibility in the presence of stationary as well as uctuating interferers, the individual’s frequency selectivity and the integrity of temporal fine-structure processing. The latter was addressed by measuring the lateralization threshold for low-frequency tones with ongoing interaural phase delays. In addition, this lateralization threshold was measured in a stationary noise background in order to assess the persistence of the ne- structure processing to interfering noise. This may play a crucial role for the ability to listen into the dips of fluctuating background interferers.