The Role of Consonant-Vowel Amplitude Ratio in the Recognition of Voiceless Stop Consonants by Listeners With Hearing Impairment Several authors have evaluated consonant-to-vowel ratio (CVR) enhancement as a means to improve speech recognition in listeners with hearing impairment, with the intention of incorporating this approach into emerging amplification technology. Unfortunately, most previous studies have enhanced CVRs by increasing consonant energy, thus possibly confounding CVR effects with consonant audibility. ... Research Article
Research Article  |   February 01, 1999
The Role of Consonant-Vowel Amplitude Ratio in the Recognition of Voiceless Stop Consonants by Listeners With Hearing Impairment
 
Author Affiliations & Notes
  • Carol A. Sammeth
    Department of Speech and Hearing Science Arizona State University Tempe
  • Michael F. Dorman
    Department of Speech and Hearing Science Arizona State University Tempe
  • Carol J. Stearns
    Department of Speech and Hearing Science Arizona State University Tempe
  • Contact author: Carol A. Sammeth, PhD, Otologics, LLC, 5445 Airport Road, Boulder, CO 80303.
  • Currently affiliated with Otologics, LLC, Boulder, CO
    Currently affiliated with Otologics, LLC, Boulder, CO×
Article Information
Hearing Disorders / Speech, Voice & Prosody / Hearing / Research Articles
Research Article   |   February 01, 1999
The Role of Consonant-Vowel Amplitude Ratio in the Recognition of Voiceless Stop Consonants by Listeners With Hearing Impairment
Journal of Speech, Language, and Hearing Research, February 1999, Vol. 42, 42-55. doi:10.1044/jslhr.4201.42
History: Received July 21, 1997 , Accepted September 29, 1998
 
Journal of Speech, Language, and Hearing Research, February 1999, Vol. 42, 42-55. doi:10.1044/jslhr.4201.42
History: Received July 21, 1997; Accepted September 29, 1998

Several authors have evaluated consonant-to-vowel ratio (CVR) enhancement as a means to improve speech recognition in listeners with hearing impairment, with the intention of incorporating this approach into emerging amplification technology. Unfortunately, most previous studies have enhanced CVRs by increasing consonant energy, thus possibly confounding CVR effects with consonant audibility. In this study, we held consonant audibility constant by reducing vowel transition and steady-state energy rather than increasing consonant energy. Performance-by-intensity (PI) functions were obtained for recognition of voiceless stop consonants (/p/, /t/, /k/) presented in isolation (burst and aspiration digitally separated from the vowel) and for consonant-vowel syllables, with readdition of the vowel /α/. There were three CVR conditions: normal CVR, vowel reduction by 6 dB, and vowel reduction by 12 dB. Testing was conducted in broadband noise fixed at 70 dB SPL and at 85 dB SPL. Six adults with sensorineural hearing impairment and 2 adults with normal hearing served as listeners. Results indicated that CVR enhancement did not improve identification performance when consonant audibility was held constant, except at the higher noise level for one listener with hearing impairment. The re-addition of the vowel energy to the isolated consonant did, however, produce large and significant improvements in phoneme identification.

Acknowledgments
This study was conducted by the third author as partial fulfillment of the requirements for a master of science degree at Arizona State University. Appreciation is expressed to Dr. Sid Bacon and Dr. David Preves for their assistance as members of the thesis committee and also to Dr. Larry Humes, Amy Neel, and one anonymous reviewer for valuable suggestions on an earlier version of this manuscript. Portions of these data were presented at the first biennial Hearing Aid Research & Development Conference, NIH, Bethesda, September 1995.
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