A Comparison of the Aided Performance and Benefit Provided by a Linear and a Two-Channel Wide Dynamic Range Compression Hearing Aid The aided performance and benefit achieved with linear and two-channel wide dynamic range compression (WDRC) in-the-canal (ITC) hearing aids were established in 55 individuals. Study participants had been wearing either linear or adaptive-frequency-response (Bass Increase at Low Levels, BILL) ITC hearing aids for approximately one year before participation in this ... Research Article
Research Article  |   February 01, 1999
A Comparison of the Aided Performance and Benefit Provided by a Linear and a Two-Channel Wide Dynamic Range Compression Hearing Aid
 
Author Affiliations & Notes
  • Larry E. Humes
    Department of Speech and Hearing Sciences Indiana University-Bloomington
  • Laurel Christensen
    Department of Communication Disorders LSU Medical Center Baton Rouge, LA
  • Tara Thomas
    Department of Communication Disorders LSU Medical Center Baton Rouge, LA
  • Fred H. Bess
    The Vanderbilt Bill Wilkerson Center Vanderbilt University School of Medicine Nashville, TN
  • Andrea Hedley-Williams
    The Vanderbilt Bill Wilkerson Center Vanderbilt University School of Medicine Nashville, TN
  • Ruth Bentler
    Department of Speech Pathology and Audiology The University of Iowa Iowa City
  • Contact author: Larry E. Humes, PhD, Department of Speech and Hearing Sciences, Indiana University, Bloomington, IN 47405. Email: humes@indiana.edu
Article Information
Hearing Aids, Cochlear Implants & Assistive Technology / Hearing / Research Articles
Research Article   |   February 01, 1999
A Comparison of the Aided Performance and Benefit Provided by a Linear and a Two-Channel Wide Dynamic Range Compression Hearing Aid
Journal of Speech, Language, and Hearing Research, February 1999, Vol. 42, 65-79. doi:10.1044/jslhr.4201.65
History: Received June 1, 1998 , Accepted October 7, 1998
 
Journal of Speech, Language, and Hearing Research, February 1999, Vol. 42, 65-79. doi:10.1044/jslhr.4201.65
History: Received June 1, 1998; Accepted October 7, 1998

The aided performance and benefit achieved with linear and two-channel wide dynamic range compression (WDRC) in-the-canal (ITC) hearing aids were established in 55 individuals. Study participants had been wearing either linear or adaptive-frequency-response (Bass Increase at Low Levels, BILL) ITC hearing aids for approximately one year before participation in this study. Outcome measures included aided performance and objective benefit in quiet and noise at a variety of speech levels (50, 60, and 75 dB SPL), at various levels of babble background (quiet, signal-to-babble ratios of +5 and +10 dB), and for various types of test materials (monosyllabic words and sentences in connected speech). Several subjective measures of aided performance (sound-quality judgments and magnitude estimates of listening effort) and relative benefit (improvement in listening effort and the Hearing Aid Performance Inventory, HAPI) were also obtained. Finally, self-report measures of hearing-aid use were also obtained using daily logs. Participants completed all outcome measures for the linear ITC hearing aids first, following 2 months of usage, and then repeated all outcome measures for the WDRC instruments after a subsequent 2-month period of use.

In general, although both types of hearing aids demonstrated significant benefit, the results indicated that the WDRC instruments were superior to the linear devices for many of the outcome measures. This tended to be the case most frequently when low speech levels were used. Many of the performance differences between devices most likely can be ascribed to differences in gain, and prescriptive approaches (DSL[i/o] vs. NAL-R), for the fixed volume control testing performed in this study.

Acknowledgments
The research reported in this article was supported at each test site by a contract provided by Dahlberg, Inc. The first author served as a paid consultant on this project and was primarily responsible for the study design, within the manufacturer’s constraints, as well as the analysis and interpretation of the results. The preparation of this work for publication was supported, in part, by a grant to the first author from the National Institute on Aging. The authors would also like to thank the 55 participants who graciously agreed to participate in this clinical trial following completion of the earlier trial. The review of this manuscript by Brian Walden and two anonymous reviewers resulted in significant improvements in its clarity. The authors appreciate their assistance.
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