Wideband acoustic immittance measurements : effects of age, gender, race, and equipment


Yezhezi Zhang

Publication Date


Document Type

Honors Thesis




Sound-Measurement, Time-domain reflectometry, Broadband amplifiers, Hearing-Sex differences, Hearing disorders-Age factors, Wideband acoustic immittance, Time domain reflectance, Titan, Mimosa, ER10x


Wideband acoustic immittance (WAI) is a family of acoustic measures that can be calculated from a pressure measurement in the ear canal with a probe microphone. Such measurements can be effective in the assessment of middle-ear disorders and the prediction of conductive hearing loss in human adults. In this study, we examined how individual characteristics including age, gender, and race affect the measurements, and we also compared the measurement results from different instruments (Titan, Mimosa, and ER10x). We found that the measurements collected from all three devices were generally consistent with each other, but the Mimosa system had slightly lower absorbance in the low frequencies due to its closer measurement location to the eardrum. We also observed that below 4.5 kHz the absorbance measurements for Chinese subjects were generally smaller than those for Caucasian subjects, whereas the opposite was observed in the higher frequencies from 4.5 to 8 kHz. Older subjects had significantly lower absorbance measurements from 2 to 4 kHz and their average spectrum was shifted leftward, which could be partially explained by age-related increases in middle-ear stiffness. We found that gender and body size (height) did not have a significant association with WAI measures. Based on the differences between Caucasian and Chinese subjects, and between age groups, we recommend that ethnicity-specific and age-specific norms of WAI measures could be helpful for diagnostic purposes, but more measurements are needed. In addition, we explored the temporal properties of WAI measures that could potentially help identify the location of abnormality in the auditory system; we demonstrated the calculation of time domain reflectance (TDR) and the estimation of crosssectional area of the ear canal based on TDR.




76 pages : illustrations. Honors project, Smith College, 2016. Includes bibliographical references (pages 74-76)

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