The Response to Sudden Change in Vocal Tract Resistance During Stop Consonant Production The speech respiratory system is configured in ways that tend to maximize its ability to respond to changes in the airway environment. Intraoral pressures remain at levels sufficient to generate reliably recognized consonant sounds even in the presence of structural deficits such as velopharyngeal inadequacy. Similar respiratory compensations occur when ... Research Article
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Research Article  |   August 01, 1997
The Response to Sudden Change in Vocal Tract Resistance During Stop Consonant Production
 
Author Affiliations & Notes
  • Jong-Ryoul Kim
    Pusan National University Pusan, Korea
  • David J. Zajac
    University of North Carolina at Chapel Hill
  • Donald W. Warren, DDS, PhD, UNC
    University of North Carolina at Chapel Hill
    Craniofacial Center, CB# 7450, School of Dentistry, Chapel Hill, NC 27599-7450
  • Robert Mayo
    University of North Carolina at Chapel Hill
  • Greg K. Essick
    University of North Carolina at Chapel Hill
Article Information
Speech, Voice & Prosody / Speech / Research Articles
Research Article   |   August 01, 1997
The Response to Sudden Change in Vocal Tract Resistance During Stop Consonant Production
Journal of Speech, Language, and Hearing Research, August 1997, Vol. 40, 848-857. doi:10.1044/jslhr.4004.848
History: Received July 26, 1996 , Accepted January 16, 1997
 
Journal of Speech, Language, and Hearing Research, August 1997, Vol. 40, 848-857. doi:10.1044/jslhr.4004.848
History: Received July 26, 1996; Accepted January 16, 1997

The speech respiratory system is configured in ways that tend to maximize its ability to respond to changes in the airway environment. Intraoral pressures remain at levels sufficient to generate reliably recognized consonant sounds even in the presence of structural deficits such as velopharyngeal inadequacy. Similar respiratory compensations occur when bite blocks and bleed valves are used to vent airway pressures. The purpose of the present study was to determine the sensitivity of the monitoring system psychophysically and to assess its physiological response to sudden, unanticipated perturbations. Twenty adults were asked to produce the utterance /pa/, and a calibrated perturbator valve permitted air to escape from the oral cavity on randomly selected productions. Respiratory responses were recorded using PERCI-SARS instrumentation. The results indicated that sudden openings of 0.14 cm2 (SD = 0.04) were detected by speakers. Compensatory respiratory responses to suprathreshold pressure-venting occurred rapidly (i.e., 27 ms [SD = 8]) after valve opening. Although peak pressure and area under the pressure pulse fell with valve opening, the magnitude of pressure was nevertheless sufficient for sound generation. Measurements of the slope of the rise in intraoral pressure after subthreshold pressure-venting in 10 participants were compared to measurements obtained from an elastic model of the upper airway. The data demonstrated a significant difference between vented and unvented conditions for the model, but not the participants. This suggests that elastic recoil is actively and unconsciously controlled in humans to compensate for losses in airway pressure during speech.

Acknowledgments
This study was supported by Grants DE07105 and DE06957, NIDR, and was performed during Dr. Kim’s tenure as a Visiting Research Scholar, UNC Craniofacial Center, Chapel Hill, NC. The authors would like to thank Richard Lutz, AA; Sue El-Jawhari, PhD; and Helga Pinkerton, CNA, for technical assistance during this study. Our thanks also to the anonymous reviewers for their excellent suggestions in several areas. Most of all, we would like to thank our secretary, Jennifer Strickland, who took the chopped-up mess we gave her and put it back into a cohesive whole.
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