Abstract:
Presbycusic listeners are reported to have difficulty hearing speech in noisy sound fields. To resolve the issue of whether this difficulty is central or peripheral, an experiment, in which the spectrum of a masking noise was manipulated to replace acoustics that a listener's peripheral hearing loss filtered out of the input, was conducted. The experimental listeners were 12 people with high-frequency hearing loss who were 65 years of age or older (5 women/7 men) and the controls were 12 young adults with normal hearing (8 women/4 men). When PB words (200 words/condition) were presented at 65 dB SPL in a flat noise (S/N = 0 dB) at zero azimuth, the controls scored 53.9% correct and, when the speech and noise were separated by 90(degrees), their score was 70.2% correct, an increase of 16.3% Under the same experimental conditions, the experimental listeners scored 44.8% correct for signal and noise at zero azimuth and 53.4% correct for 90(degrees) separation, an increase of only 8.6% When the noise presented to the experimental listeners was filtered to match their equal-loudness contours (high-frequency boost), however, their speech recognition improved to 59.5%, an increase of 14.7% over their mean score for no separation of signal from noise, evidence that their difficulty is of peripheral origin. [Work supported by DC 00174-11.]