Labelling and Discrimination of a Synthetic Fricative Continuum in Noise: A Study of Absolute Duration and Relative Onset Time Cues Categorical perception was evaluated for a nine-token voice onset time (VOT) continuum with endpoint tokens /feil/-/veil/. The synthetic speech continuum was presented in a random-level noise masker at different signal-to-noise ratios (SNR=0, +6, +12 dB) and overall presentation levels (50 and 70 dB HL). Overall labelling performance deteriorated as the ... Research Article
Research Article  |   February 01, 1996
Labelling and Discrimination of a Synthetic Fricative Continuum in Noise: A Study of Absolute Duration and Relative Onset Time Cues
 
Author Affiliations & Notes
  • Craig Formby
    Division of Otolaryngology-HNS Department of Surgery University of Maryland School of Medicine Baltimore
  • Donald G. Childers
    Department of Electrical Engineering University of Florida Gainesville
  • Ajit L. Lalwani
    Department of Electrical Engineering University of Florida Gainesville
  • Contact author: Craig Formby, PhD, Dept. of Surgery, University of Maryland Professional Building, 419 W. Redwood St., Suite 360, Baltimore, MD 21201.
    Contact author: Craig Formby, PhD, Dept. of Surgery, University of Maryland Professional Building, 419 W. Redwood St., Suite 360, Baltimore, MD 21201.×
Article Information
Hearing & Speech Perception / Acoustics / Hearing Disorders / Augmentative & Alternative Communication / Hearing / Research Articles
Research Article   |   February 01, 1996
Labelling and Discrimination of a Synthetic Fricative Continuum in Noise: A Study of Absolute Duration and Relative Onset Time Cues
Journal of Speech, Language, and Hearing Research, February 1996, Vol. 39, 4-18. doi:10.1044/jshr.3901.04
History: Received June 29, 1994 , Accepted August 14, 1995
 
Journal of Speech, Language, and Hearing Research, February 1996, Vol. 39, 4-18. doi:10.1044/jshr.3901.04
History: Received June 29, 1994; Accepted August 14, 1995

Categorical perception was evaluated for a nine-token voice onset time (VOT) continuum with endpoint tokens /feil/-/veil/. The synthetic speech continuum was presented in a random-level noise masker at different signal-to-noise ratios (SNR=0, +6, +12 dB) and overall presentation levels (50 and 70 dB HL). Overall labelling performance deteriorated as the SNR was reduced. Labelling results for the +12-dB-SNR condition reflected a category boundary at 87 ms for listeners with normal hearing sensitivity. The companion two-step discrimination function revealed better-than-chance performance between pairs of tokens labelled fail, chance performance between pairs of tokens labelled vail, and a slight performance peak at the labelling boundary between fail and vail. Listeners with high-frequency audiometric deficits produced labelling results for the +12-dB-SNR condition that were similar to normal functions measured for the 0-dB-SNR condition. These listeners were unable to discriminate two-step differences in voicing duration, but they produced a normal temporal labelling boundary. To try to understand the noncategorical discrimination data, a psychoacoustic analog for the speech continuum was evaluated. Relative onset time (ROT) difference limens (DLs) were measured as a function of the temporal onset delay of a low-frequency sawtooth waveform relative to the onset of a high-frequency noise burst. The ROT cue was used only when absolute stimulus duration could not be relied upon as a consistent cue, under conditions where a large range of random overall duration was presented to the listener. The ROT DLs were relatively invariant over a range of standard delays from 50 to 110 ms. The average DL was about 30 ms, which is consistent with the small performance peak in the synthetic speech discrimination function.

Acknowledgments
These experiments were initiated while C. Formby was in the Department of Communicative Disorders at the University of Florida. Portions of this research were presented at the “Symposium on Presbycusis: A Broad Overview,” sponsored by the Committee on Hearing, Bioacoustics, and Biomechanics, National Academy of Sciences, Washington, DC, October 23, 1990. This research was supported in part by NIH Awards (NS01113 and DC00951) to C. Formby and by an NIH grant (DC00577) to D. G. Childers. We wish to thank J. Raney, H. Olson, and N. Pinto for their assistance during this project. We also are grateful to our listeners, D. Griffin, D. Kwock, C. Ross, A. Powell, J. Goede, and H. Moon. Z. Onsan produced the figures, and L. Kennell, L. Nicholson, and M. Johnson typed various drafts of this manuscript. L. Sherlock and K. Abouchacra assisted in the statistical evaluation of the results. D. Green, S. Anderson, S. Li, M. Stone, and M. Goldstein commented on various versions of this report. We also thank several anonymous reviewers for their comments.
Order a Subscription
Pay Per View
Entire Journal of Speech, Language, and Hearing Research content & archive
24-hour access
This Article
24-hour access