Estimating Phonation Threshold Pressure Phonation threshold pressure (PTP) is the minimum subglottal pressure required to initiate vocal fold oscillation. Although potentially useful clinically, PTP is difficult to estimate noninvasively because of limitations to vocal motor control near the threshold of soft phonation. Previous investigators observed, for example, that trained subjects were unable to produce ... Research Note
Research Note  |   October 01, 1997
Estimating Phonation Threshold Pressure
 
Author Affiliations & Notes
  • Kimberly V. Fisher
    Northwestern University Evanston, IL
  • Paul R. Swank
    University of Houston Texas
Article Information
Speech, Voice & Prosody / Speech / Research Notes
Research Note   |   October 01, 1997
Estimating Phonation Threshold Pressure
Journal of Speech, Language, and Hearing Research, October 1997, Vol. 40, 1122-1129. doi:10.1044/jslhr.4005.1122
History: Received May 23, 1996 , Accepted February 11, 1997
 
Journal of Speech, Language, and Hearing Research, October 1997, Vol. 40, 1122-1129. doi:10.1044/jslhr.4005.1122
History: Received May 23, 1996; Accepted February 11, 1997

Phonation threshold pressure (PTP) is the minimum subglottal pressure required to initiate vocal fold oscillation. Although potentially useful clinically, PTP is difficult to estimate noninvasively because of limitations to vocal motor control near the threshold of soft phonation. Previous investigators observed, for example, that trained subjects were unable to produce flat, consistent oral pressure peaks during /pæ/ syllable strings when they attempted to phonate as softly as possible (Verdolini-Marston, Titze, & Druker, 1990). The present study aimed to determine if nasal airflow or vowel context affected phonation threshold pressure as estimated from oral pressure (Smitheran & Hixon, 1981) in 5 untrained female speakers with normal velopharyngeal and voice function. Nasal airflow during /p/ occlusion was observed for 3 of 5 participants when they attempted to phonate near threshold pressure. When the nose was occluded, nasal airflow was reduced or eliminated during /p/; however, individuals then evidenced compensatory changes in glottal adduction and/or respiratory effort that may be expected to alter PTP estimates. Results demonstrate the importance of monitoring nasal flow (or the flow zero point in undivided masks) when obtaining PTP measurements noninvasively. Results also highlight the need to pursue improved methods for noninvasive estimation of PTP.

Acknowledgments
The help of Kishore Pondugula, computer programmer, is gratefully acknowledged. We also thank Ron Scherer, Chuck Larson, and several anonymous readers who reviewed earlier versions of the manuscript. This project was supported in part by contract HN-031 from The Oklahoma Center for the Advancement of Science and Technology.
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