Across- and Within-Consonant Errors for Isolated Syllables in Noise Purpose A critical issue in assessing speech recognition involves understanding the factors that cause listeners to make errors. Models like the articulation index show that average error decreases logarithmically with increases in signal-to-noise ratio (SNR). The authors investigated (a) whether this log-linear relationship holds across consonants and for individual tokens ... Research Article
Research Article  |   December 01, 2014
Across- and Within-Consonant Errors for Isolated Syllables in Noise
 
Author Affiliations & Notes
  • Joseph C. Toscano
    University of Illinois at Urbana-Champaign
  • Jont. B. Allen
    University of Illinois at Urbana-Champaign
  • Disclosure: The authors have declared that no competing interests existed at the time of publication.
    Disclosure: The authors have declared that no competing interests existed at the time of publication.×
  • Correspondence to Joseph C. Toscano, who is now at Villanova University, PA: joseph.toscano@villanova.edu
  • Editor: Craig Champlin
    Editor: Craig Champlin×
  • Associate Editor: Eric Healy
    Associate Editor: Eric Healy×
Article Information
Hearing & Speech Perception / Hearing Disorders / Hearing / Research Articles
Research Article   |   December 01, 2014
Across- and Within-Consonant Errors for Isolated Syllables in Noise
Journal of Speech, Language, and Hearing Research, December 2014, Vol. 57, 2293-2307. doi:10.1044/2014_JSLHR-H-13-0244
History: Received September 11, 2013 , Revised March 25, 2014 , Accepted July 25, 2014
 
Journal of Speech, Language, and Hearing Research, December 2014, Vol. 57, 2293-2307. doi:10.1044/2014_JSLHR-H-13-0244
History: Received September 11, 2013; Revised March 25, 2014; Accepted July 25, 2014
Web of Science® Times Cited: 3

Purpose A critical issue in assessing speech recognition involves understanding the factors that cause listeners to make errors. Models like the articulation index show that average error decreases logarithmically with increases in signal-to-noise ratio (SNR). The authors investigated (a) whether this log-linear relationship holds across consonants and for individual tokens and (b) what accounts for differences in error rates at the across- and within-consonant levels.

Method Listeners with normal hearing heard CV syllables (16 consonants and 4 vowels) spoken by 14 talkers, presented at 6 SNRs. Stimuli were presented randomly, and listeners indicated which syllable they heard.

Results The log-linear relationship between error and SNR holds across consonants but breaks down at the token level. These 2 sources of variability (across- and within-consonant factors) explain the majority of listeners' errors. Moreover, simply adjusting for differences in token-level error thresholds explains 62% of the variability in listeners' responses.

Conclusions These results demonstrate that speech tests must control for the large variability among tokens, not average across them, as is commonly done in clinical practice. Accounting for token-level differences in error thresholds with listeners with normal hearing provides a basis for tests designed to diagnostically evaluate individual differences with listeners with hearing impairment.

Acknowledgments
This research was supported by a Beckman Postdoctoral Fellowship to Joseph C. Toscano.
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