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UBC Theses and Dissertations

Inter-aural difference norms for wideband absorbance (WBA) : potential for identifying otosclerosis Schlagintweit, Martine


Purpose: Wideband acoustic immittance (WAI) is a field of noninvasive diagnostic measures that are used to evaluate the status of the middle ear. Wideband absorbance (WBA) is a WAI tool that distinguishes normally-hearing from pathological middle ears with a high level of diagnostic accuracy. This work aims to further improve the diagnostic efficiency of WBA, by providing a set of normative data which represents the typical inter-aural difference of WBA in adults of Caucasian, Asian and Mixed ethnicities. Design: This retrospective analysis examined records of WBA obtained from normally-hearing adults (N=122; mean age= 24.16 yrs) using the Titan by Interacoustics immittance equipment. Norms were established for individual ear measures, and the inter-aural difference of WBA measured within-subjects. A mixed model ANOVA was used to analyze how normative WBA measures are affected by factors of ethnicity, gender, and test pressurization method. A comparison of the diagnostic efficacy of the two WBA measurements was conducted with an ROC analysis, using WBA records from 28 subjects with surgically confirmed otosclerosis as a clinical group. Results: The ROC analysis confirmed that diagnostic accuracy of WBA individual ear and inter- aural difference measures was equal for the detection of otosclerosis; however, these measurements may provide complementary information regarding middle ear status. WBA norms based on individual ear data varied significantly depending on ethnicity, gender, and test pressurization method across frequencies. WBA norms based on inter-aural difference values only varied significantly with test pressurization method across frequencies, though the difference was small and likely does not have any clinical relevance, at least for the detection of otosclerosis. iii Conclusion: WBA norms based on inter-aural difference values did not depend on population- based factors of ethnicity or gender; the same set of normative data may be used reliably across these populations. Parameterization of norms for individual ear WBA data is recommended based on ethnicity, gender and test pressurization method. Inter-aural difference norms for WBA may be instrumental in interpreting immittance results for individuals with unilateral conductive pathology, or for populations for which other forms of normative data are not available.

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