What are the normative values used to classify a normal, or Type A, tympanogram?
Margolis and Heller (1987) provide the following normative data for tympanometry for children and adults:
Figure 4. Normative tympanometry values. Copied from "The Guide to Tympanometry for Hearing Screening" published by Maico Diagnostics.
Typically, pressure is considered "normal" in the range of -150 to +25 daPa. A compliance peak within these normative values suggests a normal middle ear system. A peak outside of these limits may suggest one of several pathologies.
Jen Duffey, M.S., CCC-A has been an audiologist for Maico-Diagnostics (www.maico-diagnostics.com) for three years. She provides audiological support and education, input for new product design and function, and technical assistance. Previously, she worked for three years as an educational audiologist providing clinical services to students, ages 2 to 21 years old.