Consonant Confusions in Amplitude-Expanded Speech The perceptual consequences of expanding the amplitude variations in speech were studied under conditions in which spectral information was obscured by signal correlated noise that had an envelope correlated with the speech envelope, but had a flat amplitude spectrum. The noise samples, created individually from 22 vowel-consonant-vowel nonsense words, were ... Research Article
Research Article  |   December 01, 1996
Consonant Confusions in Amplitude-Expanded Speech
 
Author Affiliations & Notes
  • Richard L. Freyman
    Department of Communication Disorders University of Massachusetts Amherst
  • G. Patrick Nerbonne
    Department of Communication Disorders University of Massachusetts Amherst
  • Contact author: Richard L. Freyman, PhD, Department of Communication Disorders, 6 Arnold House, Box 30410, University of Massachusetts, Amherst, MA 01003-0410.
    Contact author: Richard L. Freyman, PhD, Department of Communication Disorders, 6 Arnold House, Box 30410, University of Massachusetts, Amherst, MA 01003-0410.×
Article Information
Hearing Disorders / Speech, Voice & Prosody / Hearing / Research Articles
Research Article   |   December 01, 1996
Consonant Confusions in Amplitude-Expanded Speech
Journal of Speech, Language, and Hearing Research, December 1996, Vol. 39, 1124-1137. doi:10.1044/jshr.3906.1124
History: Received January 25, 1996 , Accepted July 24, 1996
 
Journal of Speech, Language, and Hearing Research, December 1996, Vol. 39, 1124-1137. doi:10.1044/jshr.3906.1124
History: Received January 25, 1996; Accepted July 24, 1996

The perceptual consequences of expanding the amplitude variations in speech were studied under conditions in which spectral information was obscured by signal correlated noise that had an envelope correlated with the speech envelope, but had a flat amplitude spectrum. The noise samples, created individually from 22 vowel-consonant-vowel nonsense words, were used as maskers of those words, with signal-to-noise ratios ranging from –15 to 0 dB. Amplitude expansion was by a factor of 3.0 in terms of decibels. In the first experiment, presentation level for speech peaks was 80 dB SPL. Consonant recognition performance for expanded speech by 50 listeners with normal hearing was as much as 30 percentage points poorer than for unexpanded speech and the types of errors were dramatically different, especially in the midrange of S-N ratios. In a second experiment presentation level was varied to determine whether reductions in consonant levels produced by expansion were responsible for the differences between conditions. Recognition performance for unexpanded speech at 40 dB SPL was nearly equivalent to that for expanded speech at 80 dB SPL. The error patterns obtained in these two conditions were different, suggesting that the differences between conditions in Experiment 1 were due largely to expanded amplitude envelopes rather than differences in audibility.

Acknowledgments
The authors would like to thank Christopher Turner, Pamela Souza, and Lauren Forget for providing the confusion matrices from their research, Emily Stanford and Diane Tharp for their help in data collection, and Jennifer Musmon for her assistance in preparing the tables and figures. This research was supported by NIDCD #DC01533.
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