Development and Application of a Reference-Interval Approach to Tympanometric Norms Using U.S. Population Data for Ages 6-80+ Years

Abstract

Purpose: United States national data for tympanometric measures from 16,614 ears included in the National Health and Nutrition Examination Survey for 20152016 and 2017-2020 were analyzed and described. Method: Analyses were primarily descriptive and relied on distribution-free medians and cumulative distribution functions (CDFs). Differences between CDFs were examined using Cohen’s h effect size. Results are presented for the age range 6-80+ years. A reference interval (RI) approach was pursued in which the interval from the 2.5th to the 95th percentile for healthy ears was specified for peak-compensated static admittance (Ytm+), tympanometric peak pressure, tympanometric width, and equivalent acoustic ear-canal volume (Vea+). Results: Separate RIs were required for 6- to 13-year-olds compared to those 14-80+ years of age for all four tympanometric measures. For both age groups, a separate RI was warranted for each sex for Ytm+ and Vea+. For those 14-80+ years of age, a separate RI was also needed for non-Hispanic Asians for Ytm+. When these RIs were applied to the full data set, about 5%-10% of ears were found to be either below the lower limit or above the upper limit of the RI. Those ears outside the RI limits had about 5 dB higher low-frequency hearing thresholds than those within RI limits. Both Ytm+ and Vea+ were found to depend on body size. Conclusion: RIs for tympanometric measures from individuals with healthy ears were established, and when applied to the general U.S. population 6-80+ years of age, 5%-10% of ears fell outside the RIs depending on the measure.