Document Type
Article
Publication Date
2026
Publication Title
JASA: Journal of the Acoustical Society of america
Abstract
This paper investigates the physical significance of ear-canal wave quantities—such as absorbance—that are commonly measured in wideband-acoustic-immittance tests and evaluates whether these quantities uniquely characterize middle-ear function. This is explored using simulations of lumped-element and transmission-line ear canals, along with measurements in three-dimensional-printed uniform and anatomical ear canals of varying geometry, terminated by the same middle-ear simulator. The results demonstrate the following points: (1) Wave quantities computed using estimated or geometrical cross-sectional areas do not uniquely characterize the middle ear because they describe the wave interaction between ear canal and middle ear and are therefore confounded by variations in ear-canal geometry. (2) At low frequencies, the reflection of sound waves in the ear canal plays a negligible role in the middle-ear transduction mechanism because of the long sound wavelength relative to ear-canal length, and wave quantities therefore do not provide a meaningful physical characterization of middle-ear function. (3) Wave quantities computed using an invariant cross-sectional area are likely most appropriate for clinical diagnostics, as they reduce the influence of ear-canal geometry up to approximately 3 kHz. However, this simplification means that wave quantities no longer characterize the reflection of sound waves in the ear canal at any frequency.
Volume
159
First Page
2857
Last Page
2874
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Rights
Licensed to Smith College and distributed CC-BY 4.0 under the Smith College Faculty Open Access Policy.
Version
Author's Accepted Manuscript
Recommended Citation
Nørgaard, Kren Monrad; Feng, Jingxin Jessica; and Voss, Susan E., "Wideband Acoustic Immittance: Suitable Quantities for Assessing Middle-Ear Status" (2026). Engineering: Faculty Publications, Smith College, Northampton, MA.
https://scholarworks.smith.edu/egr_facpubs/160