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Volume 42 Number 4, July/August 2005, Supplement 2
Pages 63 — 78


Abstract - Evaluation of human middle ear function via an acoustic power assessment

Jont B. Allen, PhD;1* Patricia S. Jeng, PhD;2 Harry Levitt, PhD3

1Department of Electrical and Computer Engineering, University of Illinois, Urbana-Champaign, IL; 2Mimosa
Acoustics, Inc., Champaign, IL; 3Advanced Hearing Concepts, Bodega Bay, CA
Abstract — Measurements of middle ear (ME) acoustic power flow (power reflectance, power absorption, and transmittance) and normalized impedance (acoustic resistance, acoustic reactance, and impedance magnitude) were compared for their utility in clinical applications. Transmittance, a measure of the acoustic power absorbed by the ME, was found to have several important advantages over other measures of acoustic power flow. In addition to its simple and audiologically relevant physical interpretation (absorbed power), the normal transmittance curve has a simple shape that is visually similar to the ME transfer function. The acoustic impedance measures (resistance and reactance) provided important additional information about ME status and supplemented transmittance measurements. Together these measurements can help identify unusual conditions such as eardrum perforations. While this article is largely a review of the development of a commercial power reflectance measurement system, previously unpublished experimental results are presented.
Key words: acoustic impedance, acoustic power reflectance, characteristic impedance, conductive disorders, middle ear pathologies, otitis media, otoacoustic emissions, otosclerosis, resistance, transmittance.

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