Modulations in Respiratory and Laryngeal Activity Associated With Changes in Vocal Intensity During Speech We tested the hypothesis that different strategies are used to alter tracheal pressure (Pt) during sustained and transient increases in intensity. It has been suggested that the respiratory system plays the primary role in Pt changes associated with alteration in overall intensity, whereas laryngeal adjustment is primary for transient change ... Research Article
Research Article  |   August 01, 2000
Modulations in Respiratory and Laryngeal Activity Associated With Changes in Vocal Intensity During Speech
 
Author Affiliations & Notes
  • Eileen M. Finnegan
    Department of Speech Pathology and Audiology Wendell Johnson Speech and Hearing Center University of Iowa Iowa City and Department of Otolaryngology University of Iowa Hospitals and Clinics Iowa City
  • Erich S. Luschei
    Department of Speech Pathology and Audiology Wendell Johnson Speech and Hearing Center University of Iowa Iowa City and Department of Otolaryngology University of Iowa Hospitals and Clinics Iowa City
  • Henry T. Hoffman
    Department of Otolaryngology University of Iowa Hospitals and Clinics Iowa City
Article Information
Speech, Voice & Prosody / Speech / Research Articles
Research Article   |   August 01, 2000
Modulations in Respiratory and Laryngeal Activity Associated With Changes in Vocal Intensity During Speech
Journal of Speech, Language, and Hearing Research, August 2000, Vol. 43, 934-950. doi:10.1044/jslhr.4304.934
History: Received December 22, 1998 , Accepted October 26, 1999
 
Journal of Speech, Language, and Hearing Research, August 2000, Vol. 43, 934-950. doi:10.1044/jslhr.4304.934
History: Received December 22, 1998; Accepted October 26, 1999

We tested the hypothesis that different strategies are used to alter tracheal pressure (Pt) during sustained and transient increases in intensity. It has been suggested that the respiratory system plays the primary role in Pt changes associated with alteration in overall intensity, whereas laryngeal adjustment is primary for transient change in Pt related to emphasis. Tracheal pressure, obtained via tracheal puncture, airflow (U), and laryngeal electromyography from the thyroarytenoid muscle (TA EMG) were collected from 6 subjects during sentence production at different intensity levels and with various stress patterns. Using a technique described in a previous study, we computed lower airway resistance (Rlaw) from measures of Pt and U obtained during a sudden change in upper airway resistance. We used this resistance value, together with direct measures of Pt and U during speech, to derive a time-varying measure of alveolar pressure (Pa), the pressure created by respiratory muscle activity and elastic recoil of the lungs. Pa provided a measure of respiratory drive that was unaffected by laryngeal activity. Laryngeal airway resistance (Rlx) and TA EMG provided measures of laryngeal activity. The results of this study indicated that, contrary to the outcome predicted by the hypothesis, there was no difference in the strategies used to alter Pt during sustained and transient increases in intensity. Although changes in both Pa and Rlx contributed to increase in Pt, the contribution of Pa was substantially greater. On average, Pa contributed to 94% and Rlx to 6% of the increase in Pt associated with vocal intensity. A secondary purpose of the study was to determine the extent to which laryngeal muscle activity was related to Rlx during speech. We found TA EMG activity increased with intensity but was not well correlated with Rlx, suggesting that when it contracts, the TA muscle may affect intensity by loosening the cover, which allows for greater amplitude of vocal fold vibration, without necessarily increasing laryngeal airway resistance.

Acknowledgments
This research was supported by grant no. P60 DC00976 from the National Institute on Deafness and Other Communication Disorders. Special thanks to Ingo Titze, Michael Karnell, Kelly Cole, and Charles A. Miller for their comments on an earlier version of this paper.
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