Measurements of middle ear functioning- traditional (acoustic impedance and acoustic admittance) and modern (middle ear reflectance and middle ear absorbance): a review

<p class="abstract"><span lang="EN-US">Estimation of the middle ear functioning is necessary for the assessment and management of the middle ear disorders. It is also crucial for deciding upon the management of hearing loss. Though very important for audiologists and otologist clinically, there are many misconceptions behind the scientific principle/rationale and confusions related to the terminologies and units used for the measurements of middle ear functioning such as acoustic impedance, acoustic admittance, middle ear reflectance and middle ear absorbance. Literature included in this review was searched from book chapters, instrument manuals, journal articles, monographs, scientific guidelines and standard specifications on the related topics. This review work threw light and eases understanding on the principles used by different instruments to estimate various measures of middle ear functioning. It will enhance understanding of the measurements and also of the relation between different measurements of middle ear functioning. Clinically, it will help professionals in analyzing results better considering the measurements variables (if present) and bring continuity in reporting the results of middle ear functioning.</span></p><strong></strong>

An Examination of Asymmetry in Adult Tympanometric Measures

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.

Longitudinal analysis of the audiological phenotype in osteogenesis imperfecta: a follow-up study

ObjectiveThis prospective study involved a longitudinal analysis of the progression of hearing thresholds in patients with osteogenesis imperfecta.MethodsAudiometric results from 36 osteogenesis imperfecta patients (age range, 6–79 years) were compared between two test times with an average interval of 4 years. Audiometric evaluation included acoustic admittance measurements, acoustic stapedial reflex measurements, pure tone audiometry and otoacoustic emissions testing.ResultsAir conduction pure tone average, corrected for sex and age, and bone conduction pure tone average increased significantly in the study population (p < 0.05 and p < 0.001, respectively). In 14.3 per cent of the evaluated ears, an alteration in type and/or severity of hearing loss was observed.ConclusionAfter an average time interval of four years, significant changes in hearing status occurred in a population of osteogenesis imperfecta patients. These findings highlight the importance of regular audiological follow up in osteogenesis imperfecta patients, including audiometry, and measurements of acoustic admittance, acoustic stapedial reflexes and otoacoustic emissions.

Tympanometric profiles for Chinese older adults

The current study aimed at obtaining and examining the normative tympanometric findings in the Chinese older adults (60 to 90 years). The tympanometric data was collected using the Interacoustics Titan IMP 440 clinical immittance meter. This included peak static acoustic admittance (Ytm); tympanometric peak pressure (TPP); tympanometric width (TW); and ear canal volume (ECV). 146 (228 ears) Chinese older adults with normal hearing or sensorineural hearing loss were included in the study. The mean and standard deviation of the tympanometric values include: Ytm 0.48±0.28mmho; TPP -5±11daPa; TW 74±27daPa; and ECV 1.06±0.29 cc. Factors such as ear, gender and age had a minimal effect on all the four-tympanometric parameters studied. Nevertheless, there were a few differences between the present study results and the previously published data. The study results warrant the need for population and age specific normative values for clinical use.