Sreedevi Aithal

Normative wideband reflectance measures in healthy neonates

OBJECTIVE Presently, normative wideband reflectance data are available for neonates who have passed a distortion product otoacoustic emission test. However, passing the distortion product otoacoustic emission test alone does not ensure normal middle ear function. The objective of this study was to establish normative wideband reflectance data in healthy neonates with normal middle ear function, as justified by passing a battery of tests. METHOD Wideband reflectance was measured in 66 infants (mean age=46.0 h, SD=21.0, range=13.3-116.5h) who passed a test battery that included high frequency (1000 Hz) tympanometry, acoustic stapedial reflex, transient evoked otoacoustic emissions and distortion product otoacoustic emissions. RESULTS The analysis of variance (ANOVA) results showed significant variations of reflectance across the frequencies. There was no significant difference between ears and genders. The median reflectance reached a minimum of 0.21-0.24 at 1-2 kHz, but increased to 0.45-0.59 below 1 kHz and 0.24-0.52 above 2 kHz. CONCLUSIONS The normative reflectance data established in the present study were in agreement with, but marginally smaller than, those of previous normative studies, except for the Keefe et al. (2000) study. While the use of a test battery approach to ensure normal middle ear function in neonates has resulted in slightly reduced reflectance across most frequencies when compared to studies that have used only otoacoustic emissions, further research is needed to accurately determine the middle ear status of neonates using test performance measures.

Conductive Hearing Loss and Middle Ear Pathology in Young Infants Referred through a Newborn Universal Hearing Screening Program in Australia

BACKGROUND Although newborn hearing screening programs have been introduced in most states in Australia, the prevalence of conductive hearing loss and middle ear pathology in the infants referred through these programs is not known. PURPOSE This study was designed to (1) evaluate the prevalence of conductive hearing loss and middle ear pathology in infants referred by a newborn hearing screening program in north Queensland, (2) compare prevalence rates of conductive hearing loss and middle ear pathology in indigenous and nonindigenous infants, and (3) review the outcomes of those infants diagnosed with conductive hearing loss and middle ear pathology. RESEARCH DESIGN Retrospective chart review of infants referred to the Audiology Department of The Townsville Hospital was conducted. STUDY SAMPLE Chart review of 234 infants referred for one or both ears from a newborn hearing screening program in north Queensland was conducted. A total of 211 infants attended the diagnostic appointment. Review appointments to monitor hearing status were completed for 46 infants with middle ear pathology or conductive hearing loss. DATA COLLECTION AND ANALYSIS Diagnosis of hearing impairment was made using an age-appropriate battery of audiological tests. Results were analyzed for both initial and review appointments. RESULTS Mean age at initial diagnostic assessment was 47.5 days (SD = 31.3). Of the 69 infants with middle ear pathology during initial diagnostic assessment, 18 had middle ear pathology with normal hearing, 47 had conductive hearing loss, and 4 had mixed hearing loss. Prevalence of conductive hearing loss in the newborns was 2.97 per 1,000 while prevalence of middle ear pathology (with or without conductive hearing loss) was 4.36 per 1,000. Indigenous Australians or Aboriginal and Torres Strait Islander (ATSI) infants had a significantly higher prevalence of conductive hearing loss and middle ear pathology than non-ATSI infants (35.19 and 44.45% vs 17.83 and 28.66%, respectively). ATSI infants also showed poor resolution of conductive hearing loss over time with 66.67% of ATSI infants reviewed showing persistent conductive hearing loss compared to 17.86% of non-ATSI infants. Medical management of 17 infants with persistent conductive hearing loss included monitoring, antibiotic treatment, examination under anesthesia, and grommet insertion. CONCLUSIONS Conductive hearing loss was found to be a common diagnosis among infants referred through screening. ATSI infants had significantly higher rates of middle ear pathology and conductive hearing loss at birth and showed poor resolution of middle ear pathology over time compared to non-ATSI infants. Future research using a direct measure of middle ear function as an adjunct to the automated auditory brainstem response screening tool to distinguish conductive from sensorineural hearing loss may facilitate prioritization of infants for assessment, thus reducing parental anxiety and streamlining the management strategies for the respective types of hearing loss.

Wideband absorbance in young infants (0-6 months): a cross-sectional study.

BACKGROUND Wideband acoustic immittance (WAI) studies on infants have shown changes in WAI measures with age. These changes are attributed, at least in part, to developmental effects. However, developmental effects in young infants (0-6 mo) on WAI have not been systematically investigated. PURPOSE The objective of this study was to compare wideband absorbance (WBA) in healthy neonates and infants aged 1, 2, 4, and 6 mo. RESEARCH DESIGN This was a prospective cross-sectional study. All participants were assessed by using 1-kHz tympanometry, distortion product otoacoustic emission (DPOAE) tests, and WBA tests. STUDY SAMPLE Participants included 35 newborns (35 ears), 16 infants aged 1 mo (29 ears), 16 infants aged 2 mo (29 ears), 15 infants aged 4 mo (28 ears), and 14 infants aged 6 mo (27 ears). For each participant, the ears that passed both high-frequency (1-kHz) tympanometry and DPOAE tests were included for analysis. DATA COLLECTION AND ANALYSIS WBA was recorded at ambient pressure conditions, and the response consisted of 16 data points at 1/3-octave frequencies from 0.25 to 8 kHz. A mixed-model analysis of variance (ANOVA) was applied to the data in each age group to evaluate the effects of sex, ear, and frequency on WBA. WBA was compared between various age groups. In addition, a separate mixed-model ANOVA was applied to WBA data, and post hoc analyses with the Bonferroni correction were performed at each of the 16 data points at 1/3-octave frequencies across age groups to examine the effect of age on WBA. RESULTS For all age groups, WBA was highest between 1.5 and 5 kHz and lowest at frequencies of less than 1.5 kHz and greater than 5 kHz. A developmental trend was evident, with both the 0- and 6-mo-old infants being significantly different from other age groups at most frequencies. The WBA results exhibited a multipeaked pattern for infants aged 0 to 2 mo, whereas a single broad peaked pattern for 4- and 6-mo-old infants was observed. The difference in WBA between 0- and 6-mo-old infants was statistically significant across most frequencies. In contrast, the WBA results for 1- and 2-mo-old infants were comparable. There were no significant sex or ear effects on WBA for all age groups. CONCLUSIONS Developmental effects of WBA were evident for infants during the first 6 mo of life. The WBA data can be used as a reference for detecting disorders in the sound-conductive pathways (outer and middle ear) in young infants. Further development of age-specific normative WBA data in young infants is warranted.

Wideband Absorbance Outcomes in Newborns: A Comparison With High-Frequency Tympanometry, Automated Brainstem Response, and Transient Evoked and Distortion Product Otoacoustic Emissions.

Objectives: The purpose of this study was to evaluate the test performance of wideband absorbance (WBA) in terms of its ability to predict the outer and middle ear status as determined by nine reference standards. Design: Automated auditory brainstem response (AABR), high-frequency (1000 Hz) tympanometry (HFT), transient evoked otoacoustic emission (TEOAE), and distortion product otoacoustic emission (DPOAE) tests were performed on 298 ears (144 right, 154 left) of 192 (108 males, 84 females) neonates with a mean age of 43.7 hours (SD = 21.3, range = 8.3 to 152.2 hr). WBA was measured from 0.25 to 8 kHz using clicks under ambient pressure conditions. Test performance of WBA was assessed in terms of its ability to identify conductive conditions in neonates when compared with nine reference standards (including four single tests and five test batteries) using the receiver operating characteristic analysis. Results: The test performance of WBA against the test battery reference standards was better than that against single test reference standards. The area under the receiver operating characteristic curve reached a high value of 0.78 for HFT + TEOAE + DPOAE and AABR + TEOAE + DPOAE reference standards. Within the ears that passed each of the reference standards, there were no significant differences in WBA. However, for the ears that failed each of the test standards, there were significant differences in WBA. The region between 1 and 4 kHz provided the best discriminability to evaluate the conductive status compared with other frequencies. Conclusions: WBA is a desirable measure of conductive conditions in newborns due to its high performance in classifying ears with conductive loss as determined by the best performing surrogate gold standards (HFT + TEOAE + DPOAE and AABR + TEOAE + DPOAE).

Wideband Absorbance in Australian Aboriginal and Caucasian Neonates

BACKGROUND Despite the high prevalence of otitis media in Australian Aboriginal infants and children, the conductive mechanism of the outer and middle ear of Aboriginal neonates remains unclear. Differences in characteristics of the conductive pathway (outer and middle ear) between Aboriginal and Caucasian neonates have not been systematically investigated by using wideband acoustic immittance measures. PURPOSE The objective of this study was to compare wideband absorbance (WBA) in Australian Aboriginal and Caucasian neonates who passed or failed a screening test battery containing high-frequency tympanometry and distortion product otoacoustic emissions (DPOAEs). RESEARCH DESIGN A cross-sectional study design was used. The mean WBA as a function of frequency was compared between Aboriginal and non-Aboriginal neonates who passed or failed the test battery. STUDY SAMPLE A total of 59 ears from 32 Aboriginal neonates (mean age, 51.9 h; standard deviation [SD], 18.2 h; range, 22-86 h) and 281 ears from 158 Caucasian neonates (mean age, 42.4 h; SD, 23.0 h; range, 8.1-152 h) who passed or failed 1000-Hz tympanometry and DPOAEs were included in the study. DATA COLLECTION AND ANALYSIS WBA results were analyzed by using descriptive statistics and t tests with Bonferroni adjustment. An analysis of variance with repeated measures was applied to the data. RESULTS Aboriginal and Caucasian neonates had almost identical pass rates of 61%, as determined by the test battery. Despite the apparently equal pass rates, the mean WBA of Aboriginal neonates who passed the test battery was significantly lower than that of their Caucasian counterparts at frequencies between 0.4 and 2 kHz. The mean WBA of Aboriginal neonates who failed the test battery was significantly lower than that of their Caucasian counterparts who also failed the test battery at frequencies between 1.5 and 3 kHz. Both Aboriginal and Caucasian neonates who failed the test battery had significantly lower WBA values than their counterparts who passed the test battery. CONCLUSIONS This study provided convincing evidence that Aboriginal neonates had significantly lower WBA values than their Caucasian counterparts, although both groups had equal pass rates, as determined by the test battery. Although the two ethnic groups showed significant differences in WBA, the factors contributing to such differences remain undetermined. Further research is warranted to determine the factors that might account for the difference in WBA between the two ethnic groups.

Effect of ear canal pressure and age on wideband absorbance in young infants

Abstract Objective: The study investigated the effect of ear canal pressure and age on wideband absorbance (WBA) in healthy young infants. Design: Using a cross-sectional design, WBA at 0.25 to 8 kHz was obtained from infants as the ear canal pressure was swept from +200 to −300 daPa. Study sample: The participants included 29 newborns, 9 infants each at 1 and 4 months and 11 infants at 6 months of age who passed distortion product otoacoustic emissions test. Results: In general, negative-ear canal pressures reduced WBA across the frequency range, while positive-ear canal pressures resulted in reduced WBA from 0.25 to 2 kHz and above 4 kHz with an increase in absorbance between 2 and 3 kHz compared to WBA at ambient pressure. The variation in WBA below 0.5 kHz, as the pressure was varied, was the greatest in newborns. But, the variation was progressively reduced in older infants up to the age of 6 months, suggesting stiffening of the ear canal with age. Conclusions: Significant changes in WBA were observed as a function of pressure and age. In particular, developmental effects on WBA were evident during the first six months of life.

Diagnosing Middle Ear Pathology in 6- to 9-Month-Old Infants Using Wideband Absorbance: A Risk Prediction Model

Purpose The aim of this study was to develop a risk prediction model for detecting middle ear pathology in 6- to 9-month-old infants using wideband absorbance measures. Method Two hundred forty-nine infants aged 23-39 weeks (Mdn = 28 weeks) participated in the study. Distortion product otoacoustic emissions and high-frequency tympanometry were tested in both ears of each infant to assess middle ear function. Wideband absorbance was measured at ambient pressure in each participant from 226 to 8000 Hz. Absorbance results from 1 ear of each infant were used to predict middle ear dysfunction, using logistic regression. To develop a model likely to generalize to new infants, the number of variables was reduced using principal component analysis, and a penalty was applied when fitting the model. The model was validated using the opposite ears and with bootstrap resampling. Model performance was evaluated through measures of discrimination and calibration. Discrimination was assessed with the area under the receiver operating characteristic curve (AUC); and calibration, with calibration curves, which plotted actual against predicted probabilities. Results AUC of the fitted model was 0.887. The model validated adequately when applied to the opposite ears (AUC = 0.852) and with bootstrap resampling (AUC = 0.874). Calibration was satisfactory, with high agreement between predictions and observed results. Conclusions The risk prediction model had accurate discrimination and satisfactory calibration. Validation results indicate that it may generalize well to new infants. The model could potentially be used in diagnostic and screening settings. In the context of screening, probabilities provide an intuitive and flexible mechanism for setting the referral threshold that is sensitive to the costs associated with true and false-positive outcomes. In a diagnostic setting, predictions could be used to supplement visual inspection of absorbance for individualized diagnoses. Further research assessing the performance and impact of the model in these contexts is warranted.

Identifying conductive conditions in neonates using wideband acoustic immittance

Wideband acoustic immittance (WAI) is an innovative method of middle ear assessment with significant advantages over currently available clinical tests. Previous large-scale studies in neonates have assessed accuracy against evoked otoacoustic emissions but further research is needed using a more stringent gold standard. The aim of this study was to evaluate the test performance of WAI in neonates against a composite reference standard consisting of distortion-product otoacoustic emissions (DPOAEs) and high-frequency tympanometry (HFT). Five hundred and five neonates were recruited from the maternity ward of the Townsville Hospital to participate in the study. DPOAEs and HFT were performed on each neonate to assess outer and middle ear function. Wideband absorbance and complex admittance (magnitude and phase) were measured from 226 to 8000 Hz in each neonate at ambient pressure using a click stimulus. Best separation between groups that passed and failed the reference standard occurred at frequencies from...

Predicting the characteristics of wideband absorbance in ears with middle-ear pathologies

Wideband absorbance (WBA), a measure of the proportion of energy absorbed by the middle ear, is an emerging technology to detect middle-ear dysfunction. WBA results in display absorbance as a function of frequency. WBA characteristics in adults with normal middle-ear function show a broad peak between 2 and 4 kHz. While changes in WBA results in patients with middle-ear dysfunction have been described previously, the acoustical properties accounting for those changes have not been investigated. This study investigated the wideband acoustical properties of the middle ear using a spring-mass-friction mechanical system modeling technique. When the system undergoes simple harmonic motion with damping, its frequency of vibration is given by f =1/2π√(k/m), where k and m represent stiffness and mass of the system, respectively. In the presence of middle-ear dysfunction, the k to m ratio changes, resulting in reduced WBA amplitude and a change of the frequency of vibration as shown by a shift of the broad peak of...

Can resonance frequency of the outer ear be measured in neonates using wideband tympanometry

This study investigated the feasibility of measuring the resonance frequency (RF) in healthy neonates’ ears using wideband tympanometry (WBT). WBT measures admittance and absorbance as a function of frequency and ear canal pressure. Clinically, RF is the frequency at which the susceptance, the vertical component of admittance, equals zero. In this study, RF was successfully measured in 154 ears (114 newborns) out of 297 ears (182 newborns), which passed a battery of tests including automated auditory brainstem response, 1000-Hz tympanometry and distortion product otoacoustic emissions. The success rate of measuring RF in healthy neonates was 51.9%. The normative data revealed a mean RF of 323 Hz (SD = 67 Hz; range = 240-595 Hz; median = 313.5 Hz; 90% range = 246-440 Hz). No significant gender or ear effects were found. The results of the present study are consistent with the resonance frequency of the outer ear (i.e., elastic ear canal wall) in neonates using a sweep frequency impedance technique (Murakos...