A Comparison of the Benefit Provided by Well-Fit Linear Hearing Aids and Instruments With Automatic Reductions of Low-Frequency Gain In this clinical study, 110 patients seen at three different clinical facilities were fit binaurally with linear, in-the-canal (ITC) hearing aids. All patients were new hearing aid users. Each of the hearing aids was equipped with an adjustable control that could be set by one of the audiologists (Audiologist A) ... Research Article
Research Article  |   June 01, 1997
A Comparison of the Benefit Provided by Well-Fit Linear Hearing Aids and Instruments With Automatic Reductions of Low-Frequency Gain
 
Author Affiliations & Notes
  • Larry E. Humes
    Department of Speech and Hearing Sciences Indiana University Bloomington
  • Laurel A. Christensen
    Department of Communication Disorders LSU Medical Center New Orleans, LA
  • Fred H. Bess
    Division of Hearing and Speech Sciences Vanderbilt University School of Medicine Nashville, TN
  • Andrea Hedley-Williams
    Division of Hearing and Speech Sciences Vanderbilt University School of Medicine Nashville, TN
Article Information
Hearing Disorders / Hearing Aids, Cochlear Implants & Assistive Technology / Hearing / Research Articles
Research Article   |   June 01, 1997
A Comparison of the Benefit Provided by Well-Fit Linear Hearing Aids and Instruments With Automatic Reductions of Low-Frequency Gain
Journal of Speech, Language, and Hearing Research, June 1997, Vol. 40, 666-685. doi:10.1044/jslhr.4003.666
History: Received July 10, 1996 , Accepted January 10, 1997
 
Journal of Speech, Language, and Hearing Research, June 1997, Vol. 40, 666-685. doi:10.1044/jslhr.4003.666
History: Received July 10, 1996; Accepted January 10, 1997

In this clinical study, 110 patients seen at three different clinical facilities were fit binaurally with linear, in-the-canal (ITC) hearing aids. All patients were new hearing aid users. Each of the hearing aids was equipped with an adjustable control that could be set by one of the audiologists (Audiologist A) at each site to convert it from a linear instrument to an experimental nonlinear one with automatic reduction of low-frequency gain at high input levels (or base increase at low levels, BILL). Both the patient and the audiologist performing the outcome testing at each site (Audiologist B) were blind as to the present setting of the hearing aid. Each participant was enrolled in the study for a total of 12 weeks, with the hearing aid set to either the linear or BILL-processing mode of operation for the first 8 weeks and the opposite setting for a subsequent 4-week period. In summary, this was a prospective, doubleblind, crossover study of 110 new hearing-aid users. Outcome measures focused on hearing-aid benefit and included both objective and subjective measures. Objective measures were derived from scores on the Northwestern University Auditory Test No. 6 (NU-6) and the Connected Speech Test (CST) obtained for all possible combinations of two speech presentation levels (60 and 75 dB SPL), two types of background noise (cafeteria noise and multitalker babble), and two signal-to-noise ratios (+5 and +10 dB). Subjective outcome measures included magnitude estimation of listening effort (MELE), the abbreviated form of the Hearing Aid Performance Inventory (HAPI), and estimations of hearing-aid usage based on daily-use logs kept by the participants. All of these measures were used to evaluate the benefit provided by linear amplification and the benefit resulting from the experimental BILL processing. Participant preferences for the experimental BILL-processing scheme or linear processing were also examined by using a paired-comparison task at the end of the study. Results were analyzed separately for three subgroups of patients (mild, moderate, severe) formed on the basis of their average hearing loss at 500, 1000, 2000, and 4000 Hz. In all three subgroups, significant improvement in performance was observed for linear amplification and for BILL processing when compared to unaided performance. There were no significant differences in aided performance, however, between linear processing and the experimental BILL processing.

Acknowledgments
This work was supported, in part, by research contracts provided by Dahlberg, Inc. to the investigators at each of the clinical sites. The first author was not one of the clinical investigators for the study, but was hired by the study sponsor as a paid consultant while the study was underway to oversee the data collection, analyses, and internal reporting. The authors would like to express appreciation for their support to all those involved in this project at Dahlberg, Inc.—especially Melanie Raska and Tom Scheller (presently with another hearing-aid company); those at Bausch & Lomb Incorporated—especially Eric Ankerud, Heather Bornemann, and To m Crescuillo; and those involved at the participating clinical sites—especially Tara Thomas. In addition, two individuals at the University of Iowa deserve special mention for their significant contributions to this project. First, Don Schum, presently working for another hearing-aid manufacturer, played a major role in the design and development of the clinical protocol used in this study. Second, Aaron Parkinson, who assumed Don’s on-site responsibilities at the University of Iowa when Don left Iowa. Finally, preparation of this work for publication was supported, in part, by a grant from the National Institute on Aging to the first author and, in part, by the Retirement Research Foundation.
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