CC BY-NC-ND 4.0 · Semin Hear 2023; 44(01): 017-028
DOI: 10.1055/s-0043-1763293
Original Article

Fundamental Concepts for Assessment and Interpretation of Wideband Acoustic Immittance Measurements

Hammam AlMakadma*
1   Department of Otolaryngology and Communicative Disorders, School of Medicine, University of Louisville, Louisville, Kentucky
Joseph Kei*
2   Hearing Research Unit for Children, School of Health and Rehabilitative Sciences, University of Queensland, Queensland, Australia
David Yeager
1   Department of Otolaryngology and Communicative Disorders, School of Medicine, University of Louisville, Louisville, Kentucky
M. Patrick Feeney
3   Department of Otolaryngology – Head and Neck Surgery, Oregon Health and Science University, Portland, Oregon
4   VA Portland Health Care System, National Center for Rehabilitative Auditory Research, Portland, Oregon
› Author Affiliations


Assessment of middle ear impedance using noninvasive electroacoustic measurements has undergone successive developments since its first clinical application in the 1940s, and gained widespread adoption since the 1970s in the form of 226-Hz tympanometry, and applications in multifrequency tympanometry. More recently, wideband acoustic immittance (WAI) is allowing unprecedented assessments of the middle ear acoustic mechanics thanks to the ability to record responses over a wide range of frequencies. The purpose of this article is to present fundamental concepts for the assessment and interpretation of wideband measures, including a review of acoustic impedance and its relation to the mass, stiffness, and resistance components of the middle ear. Additionally, an understanding of the middle ear transfer function reveals the relationship between impedance and middle-ear gain as a function of frequency. Wideband power absorbance, a WAI measure, quantifies the efficiency of sound conduction through the middle ear over a wide range of frequencies, and can serve as an analogous clinical measure to the transfer function. The interpretation of absorbance measures in ears with or without a conductive condition using absorbance measured at ambient pressure and pressurized conditions (wideband tympanometry) is described using clinical case examples. This article serves as an introduction to the fundamental principles of WAI measurements.

* H.A. and J.K. have jointly contributed as first authors.

Publication History

Article published online:
01 March 2023

© 2023. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (

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