Sources of Error in Estimation of Laryngeal Airway Resistance in Persons With Spasmodic Dysphonia Estimation of laryngeal airway resistance is a noninvasive method that has proven useful in the study of people with normal and some types of disordered voices. We were interested in examining more closely the application of this method to persons with spasmodic dysphonia (SD), a voice disorder sometimes associated with ... Research Article
Research Article  |   February 01, 1996
Sources of Error in Estimation of Laryngeal Airway Resistance in Persons With Spasmodic Dysphonia
 
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
  • Julie M. Barkmeier
    Voice and Speech Section National Institute on Deafness and Other Communication Disorders Bethesda, MD
  • Henry T. Hoffman
    Department of Otolaryngology University of Iowa Hospitals and Clinics Iowa City
  • Contact author: Eileen M. Finnegan, Speech Pathology and Audiology, Department of Otolaryngology, University of Iowa Hospitals and Clinics, 200 Hawkins Dr. E 230 GH, Iowa City, IA 52242–1078. E-mail: finnegan@shc.uiowa.edu
Article Information
Speech, Voice & Prosodic Disorders / Voice Disorders / Speech, Voice & Prosody / Speech / Research Articles
Research Article   |   February 01, 1996
Sources of Error in Estimation of Laryngeal Airway Resistance in Persons With Spasmodic Dysphonia
Journal of Speech, Language, and Hearing Research, February 1996, Vol. 39, 105-113. doi:10.1044/jshr.3901.105
History: Received March 17, 1995 , Accepted July 11, 1995
 
Journal of Speech, Language, and Hearing Research, February 1996, Vol. 39, 105-113. doi:10.1044/jshr.3901.105
History: Received March 17, 1995; Accepted July 11, 1995

Estimation of laryngeal airway resistance is a noninvasive method that has proven useful in the study of people with normal and some types of disordered voices. We were interested in examining more closely the application of this method to persons with spasmodic dysphonia (SD), a voice disorder sometimes associated with fluctuating airflow. We speculated unstable airflow could affect the estimation of subglottal pressure and laryngeal airway resistance. Oral pressure and airflow were collected from 10 subjects with SD and 10 control subjects during repetition of /pi/. The coefficient of variation (COV) of airflow during vowel production was calculated to quantify stability of airflow. The results indicated that although some SD subjects produced steady flows during the syllable repetition task, others exhibited substantially varying flows. Inability on the part of the subject to attain steady flows could compromise the usefulness of a midpoint measure of airflow and/or estimation of subglottal pressure, resulting in sources of error in estimation of laryngeal airway resistance. As a result, of the 10 subjects with SD in this study, laryngeal airway resistance could not be estimated in 6 subjects with unsteady flows. Laryngeal airway resistance was estimated in 4 SD subjects who produced steady airflow. Two of these subjects exhibited high laryngeal airway resistance; the others exhibited normal laryngeal airway resistance.

Acknowledgment
This research was supported by grant no. P60 DC00976 from the National Institutes on Deafness and Other Communication Disorders. We gratefully acknowledge the contributions of Dr. Emily Lin for assistance with data collection and Dr. Nancy Solomon for her helpful comments on an earlier version of this manuscript.
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