Multiple Frequency Tympanometry Effects of Ear Canal Volume Compensation on Static acoustic admittance and Estimates of Middle Ear Resonance Research Article
Research Article  |   February 01, 1993
Multiple Frequency Tympanometry
 
Author Affiliations & Notes
  • Janet E. Shanks
    Va Medical Center Long Beach, Ca and University of California, Irvine
  • Richard H. Wilson
    Va Medical Center Long Beach, Ca and University of California, Irvine
  • Nancy K. Cambron
    Va Medical Center Long Beach, Ca and University of California, Irvine
  • Contact author: Janet E. Shanks, PhD, Audiology-126, VA Medical Center, 5901 East Seventh Street, Long Beach, CA 90822.
Article Information
Hearing & Speech Perception / Acoustics / Hearing Disorders / Hearing / Research Articles
Research Article   |   February 01, 1993
Multiple Frequency Tympanometry
Journal of Speech, Language, and Hearing Research, February 1993, Vol. 36, 178-185. doi:10.1044/jshr.3601.178
History: Received February 13, 1992 , Accepted July 24, 1992
 
Journal of Speech, Language, and Hearing Research, February 1993, Vol. 36, 178-185. doi:10.1044/jshr.3601.178
History: Received February 13, 1992; Accepted July 24, 1992

Three methods for compensating multiple frequency acoustic admittance measurements for ear canal volume were studied in 26 men with normal middle ear transmission systems. Peak compensated static acoustic admittance (|y|) and phase angle (ø) were calculated from sweep frequency tympanograms (226–1243 Hz in 113 Hz increments). Of the procedures used to compensate for volume in rectangular form, the ear canal pressure used to estimate volume had the largest effect on the estimate of middle ear resonance. Median resonance was 800 Hz for admittance measurements compensated at 200 daPa versus 1100 Hz for measurements compensated at –350 daPa. The remaining two methods, compensation of susceptance only versus both susceptance and conductance and compensation using the minimum volume versus separate volumes at each frequency, did not affect estimates of middle ear resonance. Estimates of middle ear resonance from compensated phase angle measurements also were compared with estimates of resonance from admittance and phase difference curves. although resonance could not be estimated from the phase difference curve, resonance estimated from the admittance difference curve agreed with the estimate from compensated phase angle.

acknowledgments
This project was sponsored by a Merit Review from the Medical Research Service, Department of Veteran affairs, Washington, DC. The authors express their appreciation to Jon Birck of the Virtual Corporation for assisting Steve Hunt in developing the custom software used in this study. We also want to thank Kristine Myers for helping in the preparation of the graphics used in this manuscript.
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