An Examination of Asymmetry in Adult Tympanometric Measures

Abstract

Background During audiologic evaluations, an examination of interaural asymmetry is commonly evaluated. To date, however, interaural differences for tympanometric indices have not been reported for adults. Without documented tympanometric right-left differences, one cannot determine if asymmetries are normal or are indicative of significant clinical asymmetries. Purpose The purpose of this study was to investigate interaural asymmetries in peak compensated static acoustic admittance (Ytm), equivalent ear canal volume (Vea), tympanometric peak pressure (TPP), and tympanometric width (TW) in normal adults. Research Design Descriptive, correlational, and inferential measures designs were employed. Study Sample Participants were 188 otologically normal Caucasian young adults (i.e., 77 females and 111 males; M = 23.0 years, standard deviation [SD] = 2.7, range = 18–30 years). Data Collection and Analyses Ytm, Vea, TPP, and TW measures were obtained bilaterally from an admittance tympanogram using a 226 Hz probe tone. Separate two-factor mixed measures analysis of variance examined the effect of ear and sex for each tympanometric index. Correlation analyses examined the association between right and left ear indices. Interaural differences in tympanometric indices were examined with independent t-tests. Critical differences, for deciding if two tympanometric indices are different between ears, were computed from the standard deviations of the right–left ear difference for statistical confidence levels of 85, 90, 95, and 99%. Results The effect of ear was not statistically significant (p > 0.05) on any tympanometric index. Females had significantly lower Ytm and smaller Vea measures than males (p < 0.05). Correlations between all right and left tympanometric indices were positive and statistically significant (p < 0.05). There were no statistically significant differences in interaural differences for any of the tympanometric indices as a function of sex (p > 0.05). Critical differences, for confidence levels for 85% to 99% confidence ranged from ± 0.20–0.36 mmhos for Ytm, ± 0.23–0.41 cm3 for Vea, ± 11.1–19.8 daPa for TPP, and ± 27.2–48.7 daPa for TW. Conclusion A clinician can use these critical differences to determine if tympanometric index interaural differences in ears of young normal Caucasian adults are statistically significant.

Patient and Device Factors Contributing to Electrically Evoked Stapedial Reflex Thresholds in Cochlear Implanted Adults

“…These findings somewhat conflict with previous research on the changes in the middle ear system based on sex. Females were reported to have stiffer (lower compliance) middle ear systems, established by the lower peak admittance values, when compared to males [14,[16][17][18]. Therefore, it would be expected that females would require higher stimulation levels to elicit an ESRT, which is contradictory to what was obtained in this study.…”

“…Recording of ASR thresholds is dependent on middle ear status and characteristics. Several findings point to sex differences in acoustic admittance measures and ear canal volume in adult humans and animals in the absence of middle ear pathology [14,16,17]. Similarly, studies point to age-related changes in middle ear immittance measures, including decreased static admittance with increasing age [14,17,18].…”