Wideband Acoustic Immittance: Normative Study and Test-Retest Reliability of Tympanometric Measurements in Adults

Purpose: The purpose of this study was to present normative data of tympanometric measurements of wideband acoustic immittance and to characterize wideband tympanograms. Method: Data were collected in 84 young adults with strictly defined normal hearing and middle ear status. Energy absorbance (EA) was measured using clicks for 1/12-octave frequencies (0.236 to 8 kHz), with the ear canal air pressure systematically varied (+200 to -300 daPa). In 40 ears, 7 consecutive trials and a trial of clinical 226-Hz acoustic admittance (Y-a) tympanometry followed. A cavity test was also conducted. Results: From the wideband EA tympanogram, several EA spectrums and EA tympanograms were derived. Descriptive statistics were performed, and population parameters were estimated. The immediate test-retest reliability was excellent. Effects of ear canal air pressure on EA were examined comprehensively. Differences in EA between tympanometric and ambient-pressure measurements were significant. Single-frequency EA tympanograms exemplified for half-octave frequencies were contrasted. The bandpass EA tympanogram, 0.236- and 1-kHz EA and Y-a tympanograms, and 226-Hz Y-a tympanogram were compared in 9 variables. Conclusions: This study established a database of wideband tympanograms in healthy adults. The data analyses will promote our understanding of the middle ear transfer function. These data will serve as a reference for further studies in clinical populations.