High-Level Psychophysical Tuning Curves Forward Masking in Normal-Hearing and Hearing-Impaired Listeners Research Article
EDITOR'S AWARD
Research Article  |   December 01, 1991
High-Level Psychophysical Tuning Curves
 
Author Affiliations & Notes
  • David A. Nelson
    Hearing Research Laboratory Departments of Otolaryngology and Communication Disorders University of Minnesota Minneapolis, MN
  • Requests for reprints should be sent to David A. Nelson, PhD, Hearing Research Laboratory, 2630 University Avenue, SE, Minneapolis, MN 55414.
Article Information
Hearing / Research Articles
Research Article   |   December 01, 1991
High-Level Psychophysical Tuning Curves
Journal of Speech, Language, and Hearing Research, December 1991, Vol. 34, 1233-1249. doi:10.1044/jshr.3406.1233
History: Received September 9, 1990 , Accepted January 31, 1991
 
Journal of Speech, Language, and Hearing Research, December 1991, Vol. 34, 1233-1249. doi:10.1044/jshr.3406.1233
History: Received September 9, 1990; Accepted January 31, 1991

Forward-masked psychophysical tuning curves (PTCs) were obtained for 1000-Hz probe tones at multiple probe levels from one ear of 26 normal-hearing listeners and from 24 ears of 21 hearing-impaired listeners with cochlear hearing loss. Comparisons between normal-hearing and hearing-impaired PTCs were made at equivalent masker levels near the tips of PTCs. Comparisons were also made of PTC characteristics obtained by fitting each PTC with three straight-line segments using least-squares fitting procedures. Abnormal frequency resolution was revealed only as abnormal downward spread of masking. The low-frequency slopes of PTCs from hearing-impaired listeners were not different from those of normal-hearing listeners. That is, hearing-impaired listeners did not demonstrate abnormal upward spread of masking when equivalent masker levels were compared. Ten hearing-impaired ears demonstrated abnormally broad PTCs, due exclusively to reduced high-frequency slopes in their PTCs. This abnormal downward spread of masking was observed only in listeners with hearing losses greater than 40 dB HL. From these results, it would appear that some, but not all, cochlear hearing losses greater than 40dB HL influence the sharp tuning capabilities usually associated with outer hair cell function.

Acknowledgments
This research was supported in part by NIDCD grants DC00110 and DC00149. The author wishes to thank N. Markman, R. Pavlov, and A. Schroder for their assistance in collecting and analyzing the data, and J. Van Essen for developing and modifying the data-collection and data-analysis software. The author is also grateful to B. C. J. Moore and an anonymous reviewer for helpful comments.
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