Effects of subtle mid-frequency auditory dysfunction upon speech discrimination in noise.

Earlier studies have indicated mid-frequency auditory dysfunction and depressed ability to discriminate speech in noise among noise-exposed listeners with high-frequency hearing loss. The present study was designed to determine whether mid-frequency dysfunction contributed to the depressed speech discrimination performance. Normal listeners, and noise-exposed and older listeners with high-frequency hearing loss listened to word lists presented in competing 'cocktail party' noise under unfiltered and low-pass filter conditions. In the low-pass filter condition the performance of the noise-exposed listeners was superior to that normal listeners, indicating that mid-frequency auditory dysfunction on the part of noise-exposed listeners does not contribute to their difficulties discriminating unfiltered speech in noise. The performance of the older listeners was below that of the two other groups in both filtered and unfiltered conditions, indicating greater difficulty discriminating speech than would be predicted only on the basis of high-frequency hearing loss.