The Objective and Subjective Evaluation of Multichannel Expansion in Wide Dynamic Range Compression Hearing Instruments Purpose The effects of multichannel expansion on the objective and subjective evaluation of 20 listeners fitted binaurally with 4-channel, digital in-the-ear hearing instruments were investigated. Method Objective evaluations were conducted in quiet using the Connected Speech Test (CST) and in noise using the Hearing in Noise Test (HINT) ... Research Article
Research Article  |   February 01, 2007
The Objective and Subjective Evaluation of Multichannel Expansion in Wide Dynamic Range Compression Hearing Instruments
 
Author Affiliations & Notes
  • Patrick N. Plyler
    University of Tennessee, Knoxville
  • Kristy J. Lowery
    University of Tennessee, Knoxville
  • Hilary M. Hamby
    University of Tennessee, Knoxville
  • Timothy D. Trine
    Starkey Laboratories, Inc., Eden Prairie, MN
  • Contact author: Patrick N. Plyler, Department of Audiology and Speech Pathology, University of Tennessee, 578 South Stadium Hall, Knoxville, TN 37996-0740. E-mail: pplyler@utk.edu.
Article Information
Hearing & Speech Perception / Hearing Disorders / Hearing / Research Articles
Research Article   |   February 01, 2007
The Objective and Subjective Evaluation of Multichannel Expansion in Wide Dynamic Range Compression Hearing Instruments
Journal of Speech, Language, and Hearing Research, February 2007, Vol. 50, 15-24. doi:10.1044/1092-4388(2007/002)
History: Received December 12, 2005 , Accepted May 15, 2006
 
Journal of Speech, Language, and Hearing Research, February 2007, Vol. 50, 15-24. doi:10.1044/1092-4388(2007/002)
History: Received December 12, 2005; Accepted May 15, 2006
Web of Science® Times Cited: 8

Purpose The effects of multichannel expansion on the objective and subjective evaluation of 20 listeners fitted binaurally with 4-channel, digital in-the-ear hearing instruments were investigated.

Method Objective evaluations were conducted in quiet using the Connected Speech Test (CST) and in noise using the Hearing in Noise Test (HINT) at 40, 50, and 60 dB SPL. Subjective evaluations were conducted by having each participant (a) rate their satisfaction regarding the amount of noise reduction they perceived daily and (b) indicate which expansion condition they preferred overall after a 2-week trial. Three expansion settings were programmed into the hearing aids: 4-channel expansion, expansion restricted to Channels 1 and 2 only, and expansion off.

Results Listeners performed significantly better in quiet (CST) and in noise (HINT) for the off condition than for either multichannel condition; however, restricting expansion to Channels 1 and 2 improved objective performance in quiet and in noise relative to the 4-channel condition. Conversely, satisfaction ratings were significantly greater for both multichannel conditions than for the off condition; however, satisfaction ratings were similar for the restricted and the 4-channel conditions. Overall, listeners preferred any form of multichannel expansion to no expansion; however, overall preference was similar for the restricted and the 4-channel conditions.

Conclusions Hearing instrument users prefer the use of multichannel expansion despite the fact multichannel expansion may significantly reduce the recognition of low-level speech in quiet and in noise. Although restricting expansion to Channels 1 and 2 (i.e., 2000 Hz and below) maintained subjective benefit for wide dynamic range compression hearing instrument users, the recognition of low-level speech was not completely preserved.

Acknowledgments
The authors would like to acknowledge the support of Starkey Laboratories for providing the hearing instruments. Findings from this research were presented during a poster session at the International Hearing Aid Conference in Lake Tahoe, CA, 2006.
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