Effects of Talker Variability on Vowel Recognition in Cochlear Implants Purpose To investigate the effects of talker variability on vowel recognition by cochlear implant (CI) users and by normal-hearing (NH) participants listening to 4-channel acoustic CI simulations. Method CI users were tested with their clinically assigned speech processors. For NH participants, 3 CI processors were simulated, using different ... Research Article
Research Article  |   December 01, 2006
Effects of Talker Variability on Vowel Recognition in Cochlear Implants
 
Author Affiliations & Notes
  • Yi-ping Chang
    University of Southern California, Los Angeles
  • Qian-Jie Fu
    University of Southern California and House Ear Institute, Los Angeles
  • Contact author: Yi-ping Chang, Department of Auditory Implants and Perception, House Ear Institute, 2100 West Third Street, Los Angeles, CA 90057. E-mail: yipingch@usc.edu.
Article Information
Hearing & Speech Perception / Acoustics / Hearing Aids, Cochlear Implants & Assistive Technology / Speech, Voice & Prosody / Hearing / Research Articles
Research Article   |   December 01, 2006
Effects of Talker Variability on Vowel Recognition in Cochlear Implants
Journal of Speech, Language, and Hearing Research, December 2006, Vol. 49, 1331-1341. doi:10.1044/1092-4388(2006/095)
History: Received April 28, 2005 , Revised August 31, 2005 , Accepted April 13, 2006
 
Journal of Speech, Language, and Hearing Research, December 2006, Vol. 49, 1331-1341. doi:10.1044/1092-4388(2006/095)
History: Received April 28, 2005; Revised August 31, 2005; Accepted April 13, 2006
Web of Science® Times Cited: 15

Purpose To investigate the effects of talker variability on vowel recognition by cochlear implant (CI) users and by normal-hearing (NH) participants listening to 4-channel acoustic CI simulations.

Method CI users were tested with their clinically assigned speech processors. For NH participants, 3 CI processors were simulated, using different combinations of carrier type and temporal envelope cutoff frequency (noise band/160 Hz, sine wave/160 Hz, and sine wave/20 Hz). Vowel recognition was measured for 4 talkers, presented in either a single-talker context (1 talker per test block) or a multi-talker context (4 talkers per test block).

Results CI users' vowel recognition was significantly poorer in the multi-talker context than in the single-talker context. When noise-band carriers were used in the simulations, NH performance was not significantly affected by talker variability. However, when sine-wave carriers were used in the simulations, NH performance was significantly affected by talker variability in both envelope filter conditions.

Conclusions Because fundamental frequency was not preserved by the 20-Hz envelope filter and only partially preserved by the 160-Hz envelope filter, both spectral and temporal cues contributed to the talker variability effects observed with sine-wave carriers. Similarly, spectral and temporal cues may have contributed to the talker variability effects observed with CI participants.

Acknowledgments
We would like to thank our participants for their time and effort in this study. We thank John J. Galvin III for assistance with editing the manuscript, and we thank our colleagues—S. Chinchilla, X. Luo, T. Li, C. Liu, and G. Nogaki—for their support and suggestions on this study. This research was supported by National Institute on Deafness and Other Communication Disorders Grant R01-DC004993.
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