Question
I recently read an article stating the values for a Type A tympanogram are .2 to 2.5. Our clinic has been using .3 to 2.0 for Type A. What is the appropriate value for compliance for Type A tympanograms?
Answer
The terms peak compliance (ml, cc or cm3) and peak static acoustic admittance (mmho) can be used interchangeably when using a 226Hz probe tone. Most references use the term static admittance (SA) when reporting results. In the most recent edition of Katz et al 2009, there is a comprehensive list of large scale studies that reported normative ranges for peak SA. Summarizing across these studies, the 90% range for a normal tympanogram is .2 to 1.8.
References:
Shanks, J., & Shohet, J (2009). Tympanometry in clinical practice. In J. Katz, L. Medwetsky, R. Burkard, & L. Hood (Eds.), Handbook of clinical audiology (6th ed.) (pp. 157-188). Baltimore: Lippincott, Williams & Wilkins.
Madsen OTOflex 100 Users Manual. 7-50-0880/11. GN Otometrics A/S Denmark 2009.
Karen Morris, MS, CCC/A is the Manager of Audiology Services for GN Otometrics. She received her Master's degree in Audiology from Purdue University. She has worked as a clinical audiologist for over 20 years in a variety of settings and has extensive clinical experience that includes evoked potentials and vestibular assessment. In her current role, she develops and implements educational programs and materials for customers and distributors.
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