Speech Understanding in Noise for Adults With Cochlear Implants: Effects of Hearing Configuration, Source Location Certainty, and Head Movement Purpose The primary purpose of this study was to assess speech understanding in quiet and in diffuse noise for adult cochlear implant (CI) recipients utilizing bimodal hearing or bilateral CIs. Our primary hypothesis was that bilateral CI recipients would demonstrate less effect of source azimuth in the bilateral CI condition ... Research Article
Research Article  |   May 17, 2018
Speech Understanding in Noise for Adults With Cochlear Implants: Effects of Hearing Configuration, Source Location Certainty, and Head Movement
 
Author Affiliations & Notes
  • René H. Gifford
    Vanderbilt University Medical Center, Nashville, TN
  • Louise Loiselle
    Arizona State University, Tempe, AZ
    MED-EL Corporation, Durham, NC
  • Sarah Natale
    Arizona State University, Tempe, AZ
  • Sterling W. Sheffield
    Walter Reed National Military Medical Center, Bethesda, MD
  • Linsey W. Sunderhaus
    Vanderbilt University Medical Center, Nashville, TN
  • Mary S. Dietrich
    Vanderbilt University Medical Center, Nashville, TN
  • Michael F. Dorman
    Arizona State University, Tempe, AZ
  • Disclosure: René H. Gifford is on the audiology advisory board for Advanced Bionics and Cochlear Americas and the clinical advisory board for Frequency Therapeutics. Louise Loiselle is now an employee of MED-EL Corporation. Michael F. Dorman is a consultant for Advanced Bionics and MED-EL.
    Disclosure: René H. Gifford is on the audiology advisory board for Advanced Bionics and Cochlear Americas and the clinical advisory board for Frequency Therapeutics. Louise Loiselle is now an employee of MED-EL Corporation. Michael F. Dorman is a consultant for Advanced Bionics and MED-EL.×
  • Correspondence to René H. Gifford: rene.gifford@vanderbilt.edu
  • Editor: Frederick (Erick) Gallun
    Editor: Frederick (Erick) Gallun×
  • Associate Editor: Richard Dowell
    Associate Editor: Richard Dowell×
Article Information
Hearing & Speech Perception / Acoustics / Hearing Aids, Cochlear Implants & Assistive Technology / Hearing / Research Articles
Research Article   |   May 17, 2018
Speech Understanding in Noise for Adults With Cochlear Implants: Effects of Hearing Configuration, Source Location Certainty, and Head Movement
Journal of Speech, Language, and Hearing Research, May 2018, Vol. 61, 1306-1321. doi:10.1044/2018_JSLHR-H-16-0444
History: Received December 5, 2016 , Revised July 27, 2017 , Accepted February 4, 2018
 
Journal of Speech, Language, and Hearing Research, May 2018, Vol. 61, 1306-1321. doi:10.1044/2018_JSLHR-H-16-0444
History: Received December 5, 2016; Revised July 27, 2017; Accepted February 4, 2018

Purpose The primary purpose of this study was to assess speech understanding in quiet and in diffuse noise for adult cochlear implant (CI) recipients utilizing bimodal hearing or bilateral CIs. Our primary hypothesis was that bilateral CI recipients would demonstrate less effect of source azimuth in the bilateral CI condition due to symmetric interaural head shadow.

Method Sentence recognition was assessed for adult bilateral (n = 25) CI users and bimodal listeners (n = 12) in three conditions: (1) source location certainty regarding fixed target azimuth, (2) source location uncertainty regarding roving target azimuth, and (3) Condition 2 repeated, allowing listeners to turn their heads, as needed.

Results (a) Bilateral CI users exhibited relatively similar performance regardless of source azimuth in the bilateral CI condition; (b) bimodal listeners exhibited higher performance for speech directed to the better hearing ear even in the bimodal condition; (c) the unilateral, better ear condition yielded higher performance for speech presented to the better ear versus speech to the front or to the poorer ear; (d) source location certainty did not affect speech understanding performance; and (e) head turns did not improve performance. The results confirmed our hypothesis that bilateral CI users exhibited less effect of source azimuth than bimodal listeners. That is, they exhibited similar performance for speech recognition irrespective of source azimuth, whereas bimodal listeners exhibited significantly poorer performance with speech originating from the poorer hearing ear (typically the nonimplanted ear).

Conclusions Bilateral CI users overcame ear and source location effects observed for the bimodal listeners. Bilateral CI users have access to head shadow on both sides, whereas bimodal listeners generally have interaural asymmetry in both speech understanding and audible bandwidth limiting the head shadow benefit obtained from the poorer ear (generally the nonimplanted ear). In summary, we found that, in conditions with source location uncertainty and increased ecological validity, bilateral CI performance was superior to bimodal listening.

Acknowledgments
This work was supported by National Institutes of Health Grant R01 DC009404, awarded to René Gifford, and National Institutes of Health Grant R01 DC010821, awarded to René Gifford and Michael Dorman. Portions of this dataset were presented at the 2012 meeting of the American Auditory Society in Scottsdale, AZ; the 12th International Conference on Cochlear Implants and Other Implantable Auditory Technologies meeting in Baltimore, MD; the 2016 Maximizing Performance in CI Recipients: Programming Concepts meeting in New York, NY; and the 2017 Conference on Implantable Auditory Prostheses in Tahoe City, CA.
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