Distortion-Product Emissions and Auditory Sensitivity in Human Ears With Normal Hearing and Cochlear Hearing Loss Distortion product emissions (DPEs) at 2f1 – f2 frequencies were measured in 53 human ears; 21 of them exhibited cochlear hearing loss. DPEs were obtained as a function of stimulus level (DPE growth curves) at seven frequency regions between 707 Hz and 5656 Hz. Several distinctly different shapes or patterns ... Research Article
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Research Article  |   October 01, 1992
Distortion-Product Emissions and Auditory Sensitivity in Human Ears With Normal Hearing and Cochlear Hearing Loss
 
Author Affiliations & Notes
  • David A. Nelson
    Department of Otolaryngology University of Minnesota Minneapolis
  • Barry P. Kimberley
    Department of Otolaryngology University of Minnesota Minneapolis
  • Contact author: David A. Nelson, PhD, Department of Otolaryngology, University of Minnesota, Box 396 UMHC, Minneapolis, MN 55455.
Article Information
Hearing & Speech Perception / Acoustics / Hearing Disorders / Hearing / Research Articles
Research Article   |   October 01, 1992
Distortion-Product Emissions and Auditory Sensitivity in Human Ears With Normal Hearing and Cochlear Hearing Loss
Journal of Speech, Language, and Hearing Research, October 1992, Vol. 35, 1142-1159. doi:10.1044/jshr.3505.1142
History: Accepted January 1, 1991 , Received June 3, 1991
 
Journal of Speech, Language, and Hearing Research, October 1992, Vol. 35, 1142-1159. doi:10.1044/jshr.3505.1142
History: Accepted January 1, 1991; Received June 3, 1991

Distortion product emissions (DPEs) at 2f1 – f2 frequencies were measured in 53 human ears; 21 of them exhibited cochlear hearing loss. DPEs were obtained as a function of stimulus level (DPE growth curves) at seven frequency regions between 707 Hz and 5656 Hz. Several distinctly different shapes or patterns of DPE growth curves were observed. These included single-segment monotonic growth curves with and without saturation at moderate and high stimulus levels, diphasic growth curves with nulls at moderate stimulus levels, and nonmonotonic growth curves with negative slopes at high stimulus levels. Low-level, irregularly shaped segments were more frequent in normal-hearing ears, suggestive of normal low-level active nonlinearities from the outer-hair-cell subsystem. High-level, steeply sloped segments were frequent in hearing-impaired ears, suggestive of residual nonlinearities from a cochlear partition without functional outer hair cells. The stimulus level at which the DPE could just be distinguished from the noise floor, the DPE detection threshold, demonstrated moderate positive correlations (r's from 0.50 to 0.81) with auditory thresholds when all ears, both normal and impaired, were considered together. Those correlations were not strong enough to quantitatively predict auditory thresholds with any great accuracy. However, DPE thresholds were able to predict abnormal auditory sensitivity with some precision. DPE thresholds correctly predicted abnormal auditory sensitivity 79% of the time in the present study, and up to 96% of the time in previous studies. These results suggest that DPE thresholds may prove useful for hearing screening in cases where cooperation from the subject is limited or where corroboration of cochlear hearing loss is required. Different patterns of DPE growth curves suggest underlying micro-mechanical differences between ears, but the differential diagnostic value of those patterns remains to be determined.

Acknowledgments
This research was supported in part by grants from the NIDCD, the American Otologic Society, and the Lions 5M International Hearing Center. The authors wish to thank Brenda Lonsbury-Martin, Martin Whitehead, and Anna Schroder for generous comments on earlier versions of this manuscript. Special appreciation goes to John Van Essen, whose programming talents made this project possible, and to Nancy Markman and Anna Schroder for their assistance during data analysis.
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