Frequency Discrimination as a Function of Signal Frequency and Level in Normal-Hearing and Hearing-Impaired Listeners Frequency difference limens (DLFs) for pure tones were obtained over a wide range of frequencies and levels from 7 normal-hearing subjects and 16 ears of 12 listeners with sensorineural hearing losses. The normal data were fitted with a general prediction equation. Variability of the data around the DLFs estimated by ... Research Article
Research Article  |   December 01, 1991
Frequency Discrimination as a Function of Signal Frequency and Level in Normal-Hearing and Hearing-Impaired Listeners
 
Author Affiliations & Notes
  • Richard L. Freyman
    University of Minnesota, Minneapolis
  • David A. Nelson
    University of Minnesota, Minneapolis
  • Requests for reprints should be sent to Richard L. Freyman, PhD, University of Massachusetts, Department of Communication Disorders, Amherst, MA 01003.
  • Currently affiliated with University of Massachusetts, Amherst.
    Currently affiliated with University of Massachusetts, Amherst.×
Article Information
Hearing / Research Articles
Research Article   |   December 01, 1991
Frequency Discrimination as a Function of Signal Frequency and Level in Normal-Hearing and Hearing-Impaired Listeners
Journal of Speech, Language, and Hearing Research, December 1991, Vol. 34, 1371-1386. doi:10.1044/jshr.3406.1371
History: Received August 27, 1990 , Accepted February 28, 1991
 
Journal of Speech, Language, and Hearing Research, December 1991, Vol. 34, 1371-1386. doi:10.1044/jshr.3406.1371
History: Received August 27, 1990; Accepted February 28, 1991

Frequency difference limens (DLFs) for pure tones were obtained over a wide range of frequencies and levels from 7 normal-hearing subjects and 16 ears of 12 listeners with sensorineural hearing losses. The normal data were fitted with a general prediction equation. Variability of the data around the DLFs estimated by the equation was quantified and used to evaluate the DLFs from the hearing-impaired listeners. The majority of DLFs from impaired listeners were poorer than one standard deviation above the estimates of the normal equation at all frequencies and sensation levels (SLs). The portion of the equation concerned with sensation level was fitted to each listener’s data at each frequency. The slopes of these functions indicated that, on average, the rate of improvement of the DLF with sensation level was similar in the two groups of subjects. These results suggest that it would be reasonable to compare DLFs from normal-hearing and hearing-impaired listeners at equivalent sensation levels. The intercepts of the DLF-intensity functions represent asymptotic values obtained at high SLs. These asymptotic DLFs were abnormal in the majority of hearing-impaired subjects, with more than half the data in excess of two standard deviations above normal. However, among those subjects, the correlation between the DLF deficit and the amount of hearing loss at the test frequency was not strong (r=+.27).

Acknowledgments
This research was supported by NIDCD grant number DC00110 and DC00149, awarded to the second author at the University of Minnesota. Special thanks to John Van Essen for developing all of the data-collection and data-analysis software. We also wish to thank Rosie Pavlov and Nancy Markman for their assistance during data collection and analysis.
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