Effect of Middle-Ear Pathology on High-Frequency Ear Canal Reflectance Measurements in the Frequency and Time Domains
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The effects of middle-ear pathology on wideband acoustic immittance and reflectance at frequencies above 6–8 kHz have not been documented, nor has the effect of such pathologies on the time-domain reflectance. We describe an approach that utilizes sound frequencies as high as 20 kHz and quantifies reflectance in both the frequency and time domains. Experiments were performed with fresh normal human temporal bones before and after simulating various middle-ear pathologies, including malleus fixation, stapes fixation, and disarticulation. In addition to experimental data, computational modeling was used to obtain fitted parameter values of middle-ear elements that vary systematically due to the simulated pathologies and thus may have diagnostic implications. Our results demonstrate that the time-domain reflectance, which requires acoustic measurements at high frequencies, varies with middle-ear condition. Furthermore, the extended bandwidth frequency-domain reflectance data was used to estimate parameters in a simple model of the ear canal and middle ear that separates three major conductive pathologies from each other and from the normal state.
Keywordsconductive hearing loss power reflectance time-domain reflectance wideband acoustic immittance middle-ear pathology
This work is dedicated to the memory of our friend and colleague Saumil N. Merchant MD. The authors thank Mike E. Ravicz who provided software to aid in the administration and analysis of velocity measurements and Daniel M. Rasetshwane for discussions surrounding data analysis and interpretation of time-domain reflectance. We also thank Diane Jones who enabled our ability to experiment on fresh human temporal bones and Salwa Masud for assistance in ear canal diameter measurements.
This work was supported by NIH Grants R01 DC004798, R01 DC008318, and a donation from Mr. Lakshmi Mittal.
Compliance with Ethical Standards
Conflict of Interest
The authors declare that they have no conflict of interest.
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