Longitudinal development of wideband reflectance tympanometry in normal and at-risk infants

An Absorbance Peak Template for Clinical Assessment of Sound Conduction in Newborn Ears

PURPOSE

Power absorbance measures recorded over a wide range of frequencies allow for clinical inferences about the outer/middle ears' acoustic mechanics. A frequency-dependent feature in the newborn wideband absorbance response, the prominent mid-frequency absorbance peak, has been linked to middle-ear resonance. However, current normative methods were not designed to assess subtle changes in such features. This work aims to develop and validate an absorbance peak template (APT) for assessment of absorbance peaks in newborns. Additional objectives are to compare test performance of absorbance peaks and APTs to existing normative methods, to demonstrate APT-based methods for categorization of abnormal absorbance peaks, and to describe absorbance peak test-retest variability.

METHOD

Peak absorbance and peak frequency were analyzed in a training data set (490 measurements in 84 newborn ears who passed transient evoked otoacoustic emissions [TEOAEs] screenings), and an APT was developed by computing normal limits on these two absorbance peak variables. Split-set analysis evaluated the reproducibility of APT, and test-retest analysis was performed. Test performance analysis, conveyed by area under the receiver operating characteristic curve (AROC) and 95% confidence intervals (CIs), compared absorbance peak variables to absorbance area indices (AAIs) in a validation data set (359 ears that passed distortion-product OAE [DPOAE] screening and 64 ears that failed). APT-based assessment paradigms for normal and abnormal ears were compared to the common absorbance normative range paradigm.

RESULTS

Split-set analysis demonstrated a good reproducibility of APT, and test-retest of absorbance peak variables showed that they were stable measures for clinical assessment. Test performance of peak absorbance (AROC = 0.83; 95% CI [0.77, 0.88]) was comparable to the top-performing AAI variables (AROC = 0.85; 95% CI [0.80, 0.90]). APT-based assessment categorized measurements based on their peak absorbance and peak frequency and enhanced the detection of subtle frequency changes that were missed by the normative range method.

CONCLUSION

Analysis of absorbance peaks guided by APT has the potential to simplify and improve assessments of sound conduction pathways in newborn ears and can be used together with or in-place of current methods for analysis of wideband absorbance data.

Comparison of wideband acoustic immittance in Chinese infants under three months of age with normal and abnormal middle ear function

OBJECTIVES

This study aims to compare the characteristics of Wideband Acoustic Immittance (WAI) in Chinese infants under three months of age, with either normal or abnormal middle ear function.

METHODS

We recruited 98 infants with either normal or abnormal middle ear function, and subsequently divided them into four groups based on their middle ear function and chronological age. The absorbances at tympanometric peak pressure (TPP) were collected across 1/3rd octave frequencies ranging from 226 to 8000 Hz.

RESULTS

Among infants with normal middle ear function, no significant differences were observed concerning ear laterality. However, significant differences were noted at 3364 Hz and 4000 Hz with respect to age. For infants with either normal or abnormal middle ear function, we found significant differences at the majority of frequencies. Additionally, the receiver operating characteristic (ROC) curves and maxima Youden index indicated that absorbances at 1682 Hz and 1297 Hz could be employed to evaluate the middle ear function of infants at 1 and 2 months of age.

CONCLUSION

This study demonstrates that WAI holds promise as a valuable tool for assessing the middle ear condition of infants at 1 and 2 months of age. Infants aged 1 and 2 years, having absorbance values equal to or greater than 0.7470 at 1682 Hz and 0.6775 at 1297 Hz respectively, may indicate normal middle ear function. Furthermore, it underscores the necessity of establishing ethnicity- and age-specific norms for WAI in infants under 3 months of age.

Use of Wideband Acoustic Immittance in Neonates and Infants

With widespread agreement on the importance of early identification of hearing loss, universal newborn hearing screening (UNHS) has become the standard of care in several countries. Despite advancements in screening technology, UNHS and early hearing detection and intervention programs continue to be burdened by high referral rates of false-positive cases due to temporary obstruction of sound in the outer/middle ear at birth. A sensitive adjunct test of middle ear at the time of screening would aid in the interpretation of screening outcomes, minimize unnecessary rescreens, and prioritize referral to diagnostic assessment for infants with permanent congenital hearing loss. Determination of middle ear status is also an important aspect of diagnostic assessment in infants. Standard single-frequency tympanometry used to determine middle ear status in infants is neither efficient nor accurate in newborns and young infants. A growing body of research has demonstrated the utility of wideband acoustic immittance (WAI) testing in both screening and diagnostic settings. Wideband power absorbance (WBA), a WAI measure, has been shown to be more sensitive than tympanometry in the assessment of outer/middle ear function in newborns. Furthermore, age-graded norms also support successful application of WBA in young infants. Despite its merits, uptake of this technology is low among pediatric audiologists and hearing screening health workers. This report describes normative data, methods for assessment and interpretation of WBA, test-retest variations, and other factors pertinent to clinical use of WAI in newborns and infants. Clinical cases illustrate the use of WAI testing in newborn and infant hearing assessment.

External and middle ear influence on envelope following responses

Considerable between-subject variability in envelope following response (EFR) amplitude limits its clinical translation. Based on a pattern of lower amplitude and larger variability in the low (<1.2 kHz) and high (>8 kHz), relative to mid (1-3 kHz) frequency carriers, we hypothesized that the between-subject variability in external and middle ear (EM) contribute to between-subject variability in EFR amplitude. It is predicted that equalizing the stimulus reaching the cochlea by accounting for EM differences using forward pressure level (FPL) calibration would at least partially improve response amplitude and reduce between-subject variability. In 21 young normal hearing adults, EFRs of four modulation rates (91, 96, 101, and 106 Hz) were measured concurrently from four frequency bands [low (0.091-1.2 kHz), mid (1-3 kHz), high (4-5.4 kHz), and very high (vHigh; 8-9.4 kHz)], respectively, with 12 harmonics each. The results indicate that FPL calibration in-ear and in a coupler leads to larger EFR amplitudes in the low and vHigh frequency bands relative to conventional coupler root-mean-square calibration. However, improvement in variability was modest with FPL calibration. This lack of a statistically significant improvement in variability suggests that the dominant source of variability in EFR amplitude may arise from cochlear and/or neural processing.

Wideband Tympanometry Findings in Healthy Neonates

OBJECTIVES

 The objective of the present study was to describe pressurized wideband absorbance at tympanometric peak pressure (WBATPP) and 0 daPa (WBA0) in healthy Caucasian neonates.

SUBJECTS

 A total of 249 ears from 249 neonates who passed a test battery of 1,000-Hz tympanometry, distortion product otoacoustic emissions and automated auditory brainstem response were included in the study.

METHOD

 WBATPP and WBA0 were averaged in one-third octave frequencies from 0.25 to 8 kHz. Data were statistically analyzed for effects of frequency, ear, and gender.

RESULTS

 Normative WBATPP and WBA0 data obtained from healthy neonates are presented. There was no significant difference between WBATPP and WBA0 at all frequencies. Both WBATPP and WBA0 demonstrated a multipeaked pattern with maxima of 0.80 and 0.72 at 1.25 to 1.5 and 6 kHz, respectively, and two minima of 0.45 and 0.49 at 0.4 to 0.5 and 4 kHz, respectively. The effects of ear and gender were not significant for both WBA measures.

CONCLUSION

 Pressurized WBATPP and WBA0 data were provided for healthy Caucasian neonates. They will be useful for the assessment of middle ear function and assist in differentiating between conductive and sensorineural hearing losses in neonates.

[Eigenvalue analysis of wideband acoustic immittance in secretory otitis media in children of different ages]

Objective:The characteristic values of broadband acoustic immittance of children of different ages during secretory otitis media were collected resonance frequency and absorption rate of middle ear in children of different ages were compared. Methods:Eighty-two children with secretory otitis media were selected for the broadband acoustic immittance test, including 62 cases （83 ears） in the young effusion group（[3.5±0.7]months）, and 20 cases （40 ears） in the older effusion group（[4.0±0.6]years old）. 82 normal children were selected for broadband acoustic immittance test in the same environment, including 62 cases （124 ears） in the younger normal group and 20 cases （40 ears） in the older normal group. The resonance frequency and absorptivity of different age groups under broadband peak pressure were compared, and the frequency absorptivity curve was drawn for analysis. Results:The resonance frequencies of older normal group and younger normal group, older effusion group and older normal group, younger effusion group and younger normal group, older effusion group and younger effusion group were statistically significant（P<0.001）. Analysis of sound energy absorption rate at different ages. There was significant difference in sound energy absorption rate between older normal group and younger normal group at 226-1155 / 4757-8000 Hz（P<0.001）. The difference of full frequency sound energy absorption rate between the older effusion group and the older normal group was statistically significant（P<0.001）, among which the difference of 866-1542 / 2520-4362 Hz absorption rate was the largest. The difference of full frequency sound energy absorption rate between young effusion group and young normal group was statistically significant（P<0.001）, and the difference of 1091-2245 / 3776-5494 Hz absorption rate was the largest. Conclusion:Middle ear effusion in children of different ages has different performance under broadband acoustic immittance peak pressure, and has its own characteristic acoustic energy absorption frequency band. This study provides a reference basis for the analysis of the characteristics of middle ear sound transmission in children with secretory otitis media in the future.

Effects of Otosclerosis on Middle Ear Function Assessed With Wideband Absorbance and Absorbed Power

OBJECTIVE

Wideband absorbance and absorbed power were evaluated in a group of subjects with surgically confirmed otosclerosis (Oto group), mean age 51.6 years. This is the first use of absorbed power in the assessment of middle ear disorders. Results were compared with control data from two groups of adults, one with normal hearing (NH group) mean age of 31 years, and one that was age- and sex-matched with the Oto group and had sensorineural hearing loss (SNHL group). The goal was to assess group differences using absorbance and absorbed power, to determine test performance in detecting otosclerosis, and to evaluate preoperative and postoperative test results.

DESIGN

Audiometric and wideband tests were performed over frequencies up to 8 kHz. The three groups were compared on wideband tests using analysis of variance to assess group mean differences. Receiver operating characteristic (ROC) curve analysis was also used to assess test accuracy at classifying ears as belonging to the Oto or control groups using the area under the ROC curve (AUC). A longitudinal design was used to compare preoperative and postoperative results at 3 and 6 months.

RESULTS

There were significant mean differences in the wideband parameters between the Oto and control groups with generally lower absorbance and absorbed power for the Oto group at ambient and tympanometric peak pressure (TPP) depending on frequency. The SNHL group had more significant differences with the Oto group than did the NH group in the high frequencies for absorbed power at ambient pressure and tympanometric absorbed power at TPP, as well as for the tympanometric tails. The greatest accuracy for classifying ears as being in the Oto group or a control group was for absorbed power at ambient pressure at 0.71 kHz with an AUC of 0.81 comparing the Oto and NH groups. The greatest accuracy for an absorbance measure was for the comparison between the Oto and NH groups for the peak-to-negative tail condition with an AUC of 0.78. In contrast, the accuracy for classifying ears into the control or Oto groups for static acoustic admittance at 226 Hz was near chance performance, which is consistent with previous findings. There were significant mean differences between preoperative and postoperative tests for absorbance and absorbed power.

CONCLUSIONS

Consistent with previous studies, wideband absorbance showed better sensitivity for detecting the effects of otosclerosis on middle ear function than static acoustic admittance at 226 Hz. This study showed that wideband absorbed power is similarly sensitive and may perform even better in some instances than absorbance at classifying ears as having otosclerosis. The use of a group that was age- and sex-matched to the Oto group generally resulted in greater differences between groups in the high frequencies for absorbed power, suggesting that age-related norms in adults may be useful for the wideband clinical applications. Absorbance and absorbed power appear useful for monitoring changes in middle ear function following surgery for otosclerosis.

Cochlear Microphonic and Summating Potential Responses from Click-Evoked Auditory Brain Stem Responses in High-Risk and Normal Infants

BACKGROUND

Examination of cochlear and neural potentials is necessary to assess sensory and neural status in infants, especially those cared for in neonatal intensive care units (NICU) who have high rates of hyperbilirubinemia and thus are at risk for auditory neuropathy (AN).

PURPOSE

The purpose of this study was to determine whether recording parameters commonly used in click-evoked auditory brain stem response (ABR) are useful for recording cochlear microphonic (CM) and Wave I in infants at risk for AN. Specifically, we analyzed CM, summating potential (SP), and Waves I, III, and V. The overall aim was to compare latencies and amplitudes of evoked responses in infants cared for in NICUs with infants in a well-baby nursery (WBN), both of which passed newborn hearing screening.

RESEARCH DESIGN

This is a prospective study in which infants who passed ABR newborn hearing screening were grouped based on their birth history (WBN and NICU). All infants had normal hearing status when tested with diagnostic ABR at about one month of age, corrected for prematurity.

STUDY SAMPLE

Thirty infants (53 ears) from the WBN [mean corrected age at test = 5.0 weeks (wks.)] and thirty-two infants (59 ears) from the NICU (mean corrected age at test = 5.7 wks.) with normal hearing were included in this study. In addition, two infants were included as comparative case studies, one that was diagnosed with AN and another case that was diagnosed with bilateral sensorineural hearing loss (SNHL).

DATA COLLECTION AND ANALYSIS

Diagnostic ABR, including click and tone-burst air- and bone-conduction stimuli were recorded. Peak Waves I, III, and V; SP; and CM latency and amplitude (peak to trough) were measured to determine if there were differences in ABR and electrocochleography (ECochG) variables between WBN and NICU infants.

RESULTS

No significant group differences were found between WBN and NICU groups for ABR waveforms, CM, or SP, including amplitude and latency values. The majority (75%) of the NICU group had hyperbilirubinemia, but overall, they did not show evidence of effects in their ECochG or ABR responses when tested at about one-month corrected age. These data may serve as a normative sample for NICU and well infant ECochG and ABR latencies at one-month corrected age. Two infant case studies, one diagnosed with AN and another with SNHL demonstrated the complexity of using ECochG and otoacoustic emissions to assess the risk of AN in individual cases.

CONCLUSIONS

CM and SPs can be readily measured using standard click stimuli in both well and NICU infants. Normative ranges for latency and amplitude are useful for interpreting ECochG and ABR components. Inclusion of ECochG and ABR tests in a test battery that also includes otoacoustic emission and acoustic reflex tests may provide a more refined assessment of the risks of AN and SNHL in infants.

Diagnosing Conductive Dysfunction in Infants Using Wideband Acoustic Immittance: Validation and Development of Predictive Models

Purpose The aims of this study were (a) to validate the wideband acoustic immittance (WAI) model developed by Myers et al. (2018a) in a new sample of neonates and (b) to develop a prediction model for diagnosing middle ear dysfunction in infants aged 6-18 months using wideband absorbance, controlling for the effect of age. Method Tympanometry, distortion product otoacoustic emissions, and WAI were measured in 124 neonates and longitudinally in 357 infants at 6, 12, and 18 months of age. Results of tympanometry and distortion product otoacoustic emissions were used to assess middle ear function of each infant. For the first study, results from the neonates were applied to the diagnostic WAI model developed by Myers et al. (2018a). For the second study, a prediction model was developed using results from the 6- to 18-month-old infants. Results from 1 ear of infants in each age group (6, 12, and 18 months) were used to develop the model. The amount of bias (overfitting) was estimated with bootstrap resampling and by applying the model to the opposite ears (the test sample). Performance was assessed using measures of discrimination (c-index) and calibration (calibration curves). Results For the validation study, the Myers et al. (2018a) model was well calibrated and had a c-index of 0.837 when applied to a new sample of neonates. Although this was lower than the apparent performance c-index of 0.876 reported by Myers et al., it was close to the bias-corrected estimate of 0.845. The model developed for 6- to 18-month-old infants had satisfactory calibration and apparent, bias-corrected, and test sample c-index of 0.884, 0.867, and 0.887, respectively. Conclusions The validated and developed models may be clinically useful, and further research validating, updating, and assessing the clinical impact of the models is warranted.

Longitudinal Development of Wideband Absorbance and Admittance Through Infancy

Purpose The aim of this article was to study the normal longitudinal development of wideband absorbance and admittance measures through infancy. Method Two hundred one infants who passed the newborn hearing screen (automated auditory brainstem response) were tested at birth and then followed up at approximately 6, 12, and 18 months of age. Most infants were of either White (86%) or Asian (11%) descent. At each test session, infants passed tympanometry and distortion product otoacoustic emission tests. High-frequency (1000-Hz) tympanometry was used at birth and 6 months of age, and low-frequency (226-Hz) tympanometry was used at 12 and 18 months of age. Wideband pressure reflectance was also measured at each session and analyzed in terms of absorbance, admittance at the probe tip, and admittance normalized for differences in ear canal area. Multilevel hierarchical models were fitted to the absorbance and admittance data to investigate for effects of age, ear side, gender, ethnicity, and frequency. Results There were considerable age effects on wideband absorbance and admittance measurements over the first 18 months of life. The most dramatic changes occurred between birth and 6 months of age, and there were significant differences between all age groups in the 3000- to 4000-Hz region. There were significant ethnicity effects that were substantial for certain combinations of ethnicity, age, and frequency (e.g., absorbance at 6000 Hz at 12 months of age). Conclusion There are large developmental effects on wideband absorbance and admittance measures through infancy. For absorbance, we recommend separate reference data be used at birth, 6 months of age, and 12-18 months of age. For admittance (both normalized and at the probe tip), we advise using separate normative regions for each age group (neonates and 6, 12, and 18 months).

Clinical benefit of wideband-tympanometry: a pediatric audiology clinical study

PURPOSE

Wideband-tympanometry (WBT) could give more informative data about the tympanic condition than the conventional tympanometry. In the actual literature, the clinical profit of wideband-tympanometry in pediatric audiological settings is not well evaluated. The aim of this study was to analyze the additional clinical benefit.

METHODS

150 children (281 ears) with normal hearing, at the age from 11 days up to 14;10 years, checked with pure tone audiometry or auditory brainstem responses (ABR) participated in this retrospective study. We divided in four age ranges (≤ 6 month; > 6 month ≤ 3 years; > 3 years ≤ 11 years; > 11 years). All children were evaluated with ENT examination including ear microscopy, conventional 226-Hz or 1000-Hz tympanometry and WBT. Ear canal volumes were determined.

RESULTS

Compared with literature data, our patients aged ≤ 3 years showed smaller mean ear canal volumes (≤  4 ml). We found a good statistical correlation between the WBT-results and 1000-Hz tympanometry but a rare correlation between WBT-results and ear microscopic findings. In the patients with pathologic ear microscopic results in all groups of age, a significant reduction of WBT-absorbance in 1000 Hz and 2000 Hz was found.

CONCLUSIONS

This study confirms that WBT collects additive data to detect the correct middle ear status. In pediatric audiology, WBT is an additional useful method to value middle ear problems and to analyze the character of infantile hearing loss. Standard guidelines for the interpretation of the pediatric population are needed. Hence, it will be necessary to determine these findings in a larger number of infantile ears.

Optimizing Clinical Interpretation of Distortion Product Otoacoustic Emissions in Infants

OBJECTIVES

The purpose of this study was to analyze distortion product otoacoustic emission (DPOAE) level and signal to noise ratio in a group of infants from birth to 4 months of age to optimize prediction of hearing status. DPOAEs from infants with normal hearing (NH) and hearing loss (HL) were used to predict the presence of conductive HL (CHL), sensorineural HL (SNHL), and mixed HL (MHL). Wideband ambient absorbance was also measured and compared among the HL types.

DESIGN

This is a prospective, longitudinal study of 279 infants with verified NH and HL, including conductive, sensorineural, and mixed types that were enrolled from a well-baby nursery and two neonatal intensive care units in Cincinnati, Ohio. At approximately 1 month of age, DPOAEs (1-8 kHz), wideband absorbance (0.25-8 kHz), and air and bone conduction diagnostic tone burst auditory brainstem response (0.5-4 kHz) thresholds were measured. Hearing status was verified at approximately 9 months of age with visual reinforcement audiometry (0.5-4 kHz). Auditory brainstem response air conduction thresholds were used to assign infants to an NH or HL group, and the efficacy of DPOAE data to classify ears as NH or HL was analyzed using receiver operating characteristic (ROC) curves. Two summary statistics of the ROC curve were calculated: the area under the ROC curve and the point of symmetry on the curve at which the sensitivity and specificity were equal. DPOAE level and signal to noise ratio cutoff values were defined at each frequency as the symmetry point on their respective ROC curve, and DPOAE results were combined across frequency in a multifrequency analysis to predict the presence of HL.

RESULTS

Single-frequency test performance of DPOAEs was best at mid to high frequencies (3-8 kHz) with intermediate performance at 1.5 and 2 kHz and chance performance at 1 kHz. Infants with a conductive component to their HL (CHL and MHL combined) displayed significantly lower ambient absorbance values than the NH group. No differences in ambient absorbance were found between the NH and SNHL groups. Multifrequency analysis resulted in the best prediction of HL for the SNHL/MHL group with poorer sensitivity values when infants with CHL were included.

CONCLUSIONS

Clinical interpretation of DPOAEs in infants can be improved by using age-appropriate normative ranges and optimized cutoff values. DPOAE interpretation is most predictive at higher F2 test frequencies in young infants (2-8 kHz) due to poor test performance at 1 to 1.5 kHz. Multifrequency rules can be used to improve sensitivity while balancing specificity. Last, a sensitive middle ear measure such as wideband absorbance should be included in the test battery to assess possibility of a conductive component to the HL.

Longitudinal Development of Distortion Product Otoacoustic Emissions in Infants With Normal Hearing

OBJECTIVES

The purpose of this study was to describe normal characteristics of distortion product otoacoustic emission (DPOAE) signal and noise level in a group of newborns and infants with normal hearing followed longitudinally from birth to 15 months of age.

DESIGN

This is a prospective, longitudinal study of 231 infants who passed newborn hearing screening and were verified to have normal hearing. Infants were enrolled from a well-baby nursery and two neonatal intensive care units (NICUs) in Cincinnati, OH. Normal hearing was confirmed with threshold auditory brainstem response and visual reinforcement audiometry. DPOAEs were measured in up to four study visits over the first year after birth. Stimulus frequencies f1 and f2 were used with f2/f1 = 1.22, and the DPOAE was recorded at frequency 2f1-f2. A longitudinal repeated-measure linear mixed model design was used to study changes in DPOAE level and noise level as related to age, middle ear transfer, race, and NICU history.

RESULTS

Significant changes in the DPOAE and noise levels occurred from birth to 12 months of age. DPOAE levels were the highest at 1 month of age. The largest decrease in DPOAE level occurred between 1 and 5 months of age in the mid to high frequencies (2 to 8 kHz) with minimal changes occurring between 6, 9, and 12 months of age. The decrease in DPOAE level was significantly related to a decrease in wideband absorbance at the same f2 frequencies. DPOAE noise level increased only slightly with age over the first year with the highest noise levels in the 12-month-old age range. Minor, nonsystematic effects for NICU history, race, and gestational age at birth were found, thus these results were generalizable to commonly seen clinical populations.

CONCLUSIONS

DPOAE levels were related to wideband middle ear absorbance changes in this large sample of infants confirmed to have normal hearing at auditory brainstem response and visual reinforcement audiometry testing. This normative database can be used to evaluate clinical results from birth to 1 year of age. The distributions of DPOAE level and signal to noise ratio data reported herein across frequency and age in normal-hearing infants who were healthy or had NICU histories may be helpful to detect the presence of hearing loss in infants.

Normative Wideband Acoustic Immittance Measurements in Caucasian and Aboriginal Children

Purpose The aims of this study were to develop normative data for wideband acoustic immittance (WAI) measures in Caucasian and Australian Aboriginal children and compare absorbance measured at 0 daPa (WBA₀) and tympanometric peak pressure (TPP; WBA_TPP) between the 2 groups of children. Additional WAI measures included resonance frequency, equivalent ear canal volume, TPP, admittance magnitude (YM), and phase angle (YA). Method A total of 171 ears from 171 Caucasian children and 87 ears from 87 Aboriginal children who passed a test battery consisting of 226-Hz tympanometry, transient evoked otoacoustic emissions, and pure tone audiometry were included in the study. WAI measures were obtained under pressurized conditions using wideband tympanometry. Data for WBA₀, WBA_TPP, YM, and YA were averaged in one-third octave frequencies from 0.25 to 8 kHz. Results There was no significant ear effect on all of the 7 measures for both groups of children. Similarly, there was no significant gender effect on all measures except for WBA_TPP in Aboriginal children. Aboriginal boys had significantly higher WBA_TPP than girls at 1.5 and 2 kHz. A significant effect of ethnicity was also noted for WBA_TPP at 3, 4, and 8 kHz, with Caucasian children demonstrating higher WBA_TPP than Aboriginal children. However, the effect size and observed power of the analyses were small for both effects. Conclusion This study developed normative data for 7 WAI measures, namely, WBA₀, WBA_TPP, TPP, Veq, RF, YM, and YA, for Caucasian and Aboriginal children. In view of the high similarity of the normative data between Caucasian and Aboriginal children, it was concluded that separate ethnic-specific norms are not required for diagnostic purposes.

A Longitudinal Analysis of Pressurized Wideband Absorbance Measures in Healthy Young Infants

OBJECTIVES

Wideband absorbance (WBA) is an emerging technology to evaluate the conductive pathway (outer and middle ear) in young infants. While a wealth of research has been devoted to measuring WBA at ambient pressure, few studies have investigated the use of pressurized WBA with this population. The purpose of this study was to investigate the effect of age on WBA measured under pressurized conditions in healthy infants from 0 to 6 months of age.

DESIGN

Forty-four full-term healthy neonates (17 males and 27 females) participated in a longitudinal study. The neonates were assessed at 1-month intervals from 0 to 6 months of age using high-frequency tympanometry, acoustic stapedial reflex, distortion product otoacoustic emissions, and pressurized WBA. The values of WBA at tympanometric peak pressure (TPP) and 0 daPa across the frequencies from 0.25 to 8 kHz were analyzed as a function of age.

RESULTS

A linear mixed model analysis, applied to the data, revealed significantly different WBA patterns among the age groups. In general, WBA measured at TPP and 0 daPa decreased at low frequencies (<0.4 kHz) and increased at high frequencies (2 to 5and 8 kHz) with age. Specifically, WBA measured at TPP and 0 daPa in 3- to 6-month-olds was significantly different from that of 0- to 2-month-olds at low (0.25 to 0.31 kHz) and high (2 to 5 and 8 kHz) frequencies. However, there were no significant differences between WBA measured at TPP and 0 daPa for infants from 3 to 6 months of age.

CONCLUSIONS

The present study provided clear evidence of maturation of the outer and middle ear system in healthy infants from birth to 6 months. Therefore, age-specific normative data of pressurized WBA are warranted.

Normative wideband absorbance measures in healthy neonates in Korea: A preliminary study

INTRODUCTION

The usefulness of wideband absorbance (WBA) in newborns is well-demonstrated. However, it is still not clear whether there might be a difference according to ethnicity with respect to ambient WBA; therefore, further investigation is necessary to evaluate ethnic-specific normative WBA values in newborns.

METHODS

Twenty-one newborns (41 ears) were recruited from the well-baby nursery at a tertiary referral center. All newborn infants who were born at 38 weeks' to 41 weeks' gestation with a normal birth weight (range: 2.5-4.5 kg) and who passed a newborn hearing screening test with distortion product otoacoustic emissions were enrolled. Ambient absorbance values were measured on frequencies ranging from 226 Hz to 6300 Hz (i.e., 250 Hz, 315 Hz, 400 Hz, 500 Hz, 620 Hz, 800 Hz, 1000 Hz, 1250 Hz, 1600 Hz, 2000 Hz, 2500 Hz, 3150 Hz, 4000 Hz, 5000 Hz, and 6300 Hz). The results of median absorbance were compared with the WBA values of Caucasian infants and Korean adults.

RESULTS

The gestational age of the study group was 38 weeks ± 6.67 days. In a gender comparison, absorbance of female neonate was significantly higher at 3150 Hz, 4000 Hz, and 5000 Hz than in male. Based on the test frequencies, the medians of the Korean infant WBA values and Caucasian infants are significantly different from one another, except at 1600 Hz, 3150 Hz, and 4000 Hz. The results of a median absorbance comparison between Korean infant and adults WBA values showed that the medians of the two studies were significantly different except at 1250 Hz.

CONCLUSION

We analyzed the normative WBA values measured at ambient pressures in Korean newborns. The comparative analysis between the normative values of two different ethnic groups may infer a possible difference in the normative WBA values. The absorbance from Korean infant ears is substantially different from that from adult's ears. A large-scale study is required to establish normative WBA values to be used for the screening of outer and middle ear status in newborns.

Normative Wideband Reflectance, Equivalent Admittance at the Tympanic Membrane, and Acoustic Stapedius Reflex Threshold in Adults

OBJECTIVES

Wideband acoustic immittance (WAI) measures such as pressure reflectance, parameterized by absorbance and group delay, equivalent admittance at the tympanic membrane (TM), and acoustic stapedius reflex threshold (ASRT) describe middle ear function across a wide frequency range, compared with traditional tests employing a single frequency. The objective of this study was to obtain normative data using these tests for a group of normal-hearing adults and investigate test-retest reliability using a longitudinal design.

DESIGN

A longitudinal prospective design was used to obtain normative test and retest data on clinical and WAI measures. Subjects were 13 males and 20 females (mean age = 26 years). Inclusion criteria included normal audiometry and clinical immittance. Subjects were tested on two separate visits approximately 1 month apart. Reflectance and equivalent admittance at the TM were measured from 0.25 to 8.0 kHz under three conditions: at ambient pressure in the ear canal and with pressure sweeps from positive to negative pressure (downswept) and negative to positive pressure (upswept). Equivalent admittance at the TM was calculated using admittance measurements at the probe tip that were adjusted using a model of sound transmission in the ear canal and acoustic estimates of ear-canal area and length. Wideband ASRTs were measured at tympanometric peak pressure (TPP) derived from the average TPP of downswept and upswept tympanograms. Descriptive statistics were obtained for all WAI responses, and wideband and clinical ASRTs were compared.

RESULTS

Mean absorbance at ambient pressure and TPP demonstrated a broad band-pass pattern typical of previous studies. Test-retest differences were lower for absorbance at TPP for the downswept method compared with ambient pressure at frequencies between 1.0 and 1.26 kHz. Mean tympanometric peak-to-tail differences for absorbance were greatest around 1.0 to 2.0 kHz and similar for positive and negative tails. Mean group delay at ambient pressure and at TPP were greatest between 0.32 and 0.6 kHz at 200 to 300 μsec, reduced at frequencies between 0.8 and 1.5 kHz, and increased above 1.5 kHz to around 150 μsec. Mean equivalent admittance at the TM had a lower level for the ambient method than at TPP for both sweep directions below 1.2 kHz, but the difference between methods was only statistically significant for the comparison between the ambient method and TPP for the upswept tympanogram. Mean equivalent admittance phase was positive at all frequencies. Test-retest reliability of the equivalent admittance level ranged from 1 to 3 dB at frequencies below 1.0 kHz, but increased to 8 to 9 dB at higher frequencies. The mean wideband ASRT for an ipsilateral broadband noise activator was 12 dB lower than the clinical ASRT, but had poorer reliability.

CONCLUSIONS

Normative data for the WAI test battery revealed minor differences for results at ambient pressure compared with tympanometric methods at TPP for reflectance, group delay, and equivalent admittance level at the TM for subjects with middle ear pressure within ±100 daPa. Test-retest reliability was better for absorbance at TPP for the downswept tympanogram compared with ambient pressure at frequencies around 1.0 kHz. Large peak-to-tail differences in absorbance combined with good reliability at frequencies between about 0.7 and 3.0 kHz suggest that this may be a sensitive frequency range for interpreting absorbance at TPP. The mean wideband ipsilateral ASRT was lower than the clinical ASRT, consistent with previous studies. Results are promising for the use of a wideband test battery to evaluate middle ear function.

The Effect of Ethnicity on Wideband Absorbance of Neonates with Healthy Middle Ear Functions in Malaysia: A Preliminary Study

BACKGROUND AND OBJECTIVES

Although ethnicity effect on wideband absorbance (WBA) findings was evident for adults, its effect on neonates has not been established yet. This study aimed to investigate the influence of ethnicity on WBA measured at 0 daPa from neonates with healthy middle ear functions.

SUBJECTS AND METHODS

Participants were 99 normal, healthy, full-term newborn babies with chronological age between 11 and 128 hours of age (mean=46.73, standard deviation=26.36). A cross-sectional study design was used to measure WBA at 16 one-third octave frequency points from 99 neonates comprising of three ethnic groups: Malays (n=58), Chinese (n=13) and Indians (n=28). A total of 165 ears (83.3%) that passed a battery of tests involving distortion product otoacoustic emissions, 1 kHz tympanometry and acoustic stapedial reflex were further tested using WBA. Moreover, body size measurements were recorded from each participant.

RESULTS

The Malays and Indians neonates showed almost identical WBA response across the frequency range while the Chinese babies showed lower absorbance values between 1.25 kHz and 5 kHz. However, the differences observed in WBA between the three ethnic groups were not statistically significant (p=0.23). Additionally, there were no statistically significant difference in birth weight, height and head circumference among the three ethnic groups.

CONCLUSIONS

This study showed that Malays, Chinese and Indians neonates were not significantly different in their WBA responses. In conclusion, to apply for the ethnic-specific norms is not warranted when testing neonates from population constitute of these three ethnicities.

Pressurized Wideband Absorbance Findings in Healthy Neonates: A Preliminary Study

PURPOSE

The present study aimed to establish normative data for wideband absorbance (WBA) measured at tympanometric peak pressure (TPP) and 0 daPa and to assess the test-retest reliability of both measurements in healthy neonates.

METHOD

Participants of this cross-sectional study included 99 full-term neonates (165 ears) with mean chronological age of 46.7 hrs (SD = 26.3 hrs). Of the 99 neonates, 58 were Malay, 28 were Indian, and 13 were Chinese. The neonates who passed high-frequency (1 kHz) tympanometry, acoustic stapedial reflex, and distortion product otoacoustic emission screening tests were assessed using a pressurized WBA test (wideband tympanometry). To reduce the number of measurement points, the WBA responses were averaged to 16 one-third octave frequency bands from 0.25 to 8 kHz. A mixed-model analysis of variance was applied to the data to investigate the effects of frequency, ear, gender, and ethnicity on WBA. The analysis of variance was also used to compare between WBA measured at TPP and 0 daPa. An interclass correlation coefficient test was applied at each of the 16 frequency bands to measure the test-retest reliability of WBA at TPP and 0 daPa.

RESULTS

Both WBA measurements at TPP and 0 daPa exhibited a multipeaked pattern with 2 maxima at 1.25-1.6 kHz and 6.3 kHz and 2 minima at 0.5 and 4 kHz. The mean WBA measured at TPP was significantly higher than that measured at 0 daPa at 0.25, 0.4, 0.5, 1.25, and 1.6 kHz only. A normative data set was developed for absorbance at TPP and at 0 daPa. There was no significant effect of ethnicity, gender, and ear on both measurements of WBA. The test-retest reliability of WBA at TPP and 0 daPa was high with the interclass correlation coefficient ranging from 0.77 to 0.97 across the frequencies.

CONCLUSIONS

Normative data of WBA measured at TPP and 0 daPa for neonates were provided in the present study. Although WBA at TPP was slightly higher than the WBA measured at 0 daPa at some frequencies below 2 kHz, the WBA patterns of the 2 measurements were nearly identical. Moreover, the test-retest reliability of both WBA measurements was high.

Monitoring neonates for ototoxicity

OBJECTIVES

Neonates admitted to the neonatal intensive care unit (NICU) are at greater risk of permanent hearing loss compared to infants in well mother and baby units. Several factors have been associated with this increased prevalence of hearing loss, including congenital infections (e.g. cytomegalovirus or syphilis), ototoxic drugs (such as aminoglycoside or glycopeptide antibiotics), low birth weight, hypoxia and length of stay. The aetiology of this increased prevalence of hearing loss remains poorly understood.

DESIGN

Here we review current practice and discuss the feasibility of designing improved ototoxicity screening and monitoring protocols to better identify acquired, drug-induced hearing loss in NICU neonates.

STUDY SAMPLE

A review of published literature.

CONCLUSIONS

We conclude that current audiological screening or monitoring protocols for neonates are not designed to adequately detect early onset of ototoxicity. This paper offers a detailed review of evidence-based research, and offers recommendations for developing and implementing an ototoxicity monitoring protocol for young infants, before and after discharge from the hospital.

Wideband acoustic immittance in children with Down syndrome: prediction of middle-ear dysfunction, conductive hearing loss and patent PE tubes

OBJECTIVE

The purpose of this study was to evaluate pressurised wideband acoustic immittance (WAI) tests in children with Down syndrome (DS) and in typically developing children (TD) for prediction of conductive hearing loss (CHL) and patency of pressure equalising tubes (PETs).

DESIGN

Audiologic diagnosis was determined by audiometry in combination with distortion-product otoacoustic emissions, 0.226 kHz tympanometry and otoscopy. WAI results were compared for ears within diagnostic categories (Normal, CHL and PET) and between groups (TD and DS).

STUDY SAMPLE

Children with DS (n = 40; mean age 6.4 years), and TD children (n = 48; mean age 5.1 years) were included.

RESULTS

Wideband absorbance was significantly lower at 1-4 kHz in ears with CHL compared to NH for both TD and DS groups. In ears with patent PETs, wideband absorbance and group delay (GD) were larger than in ears without PETs between 0.25 and 1.5 kHz. Wideband absorbance tests were performed similarly for prediction of CHL and patent PETs in TD and DS groups.

CONCLUSIONS

Wideband absorbance and GD revealed specific patterns in both TD children and those with DS that can assist in detection of the presence of significant CHL, assess the patency of PETs, and provide frequency-specific information in the audiometric range.

Pressurized Wideband Acoustic Stapedial Reflex Thresholds: Normal Development and Relationships to Auditory Function in Infants

This study analyzed effects of pressurization on wideband acoustic stapedial-muscle reflex (ASR) tests in infants cared for in normal newborn (NN) and neonatal intensive care units (NICU). Effects of hearing-screening outcomes on ASR threshold measurements were also evaluated, and a subsequent longitudinal study established normative threshold ranges over the first year after birth. An initial experiment compared thresholds in newborns measured at ambient pressure in the ear canal and at the tympanometric peak pressure. ASR thresholds for broadband noise were higher for ears that did not pass newborn hearing screening and ASR threshold was 14 dB higher for real-ear compared to coupler conditions. Effects of pressurization were significant for ears that passed screening; thus, ASR testing in infants should be conducted at tympanometric peak pressure. ASR threshold was significantly higher for ears that referred on transient evoked otoacoustic emissions and Auditory Brainstem Response (ABR) screening tests and also for ears with conductive and sensorineural hearing loss diagnosed by ABR. Developmental ASR changes were significant over the first year for both normal and NICU infants. Wideband pressurized ASR thresholds are a clinically relevant measure of newborn hearing screening and diagnostic outcomes.

Maturation of middle ear transmission in children

The goal of the current study was to characterize the normative features of wideband acoustic immittance in children for describing the functional maturation of the middle ear in 5 to 12-year-old children. Absorbance and group delay were measured in adults and three groups of children, 5-6, 7-9 and 10-12-year-olds, in a cross-sectional design. Absorbance showed significant effects of the age group in four out of ten center frequencies of one-half-octave bins from 211 to 6000 Hz, while there was no significant effect for group delay at any frequency. Older children (10-12 years) showed absorbance similar to adults. Test-retest reliability was high for absorbance for all age groups. However, group delay was modestly reliable only for adults. We conclude that the middle ear transmission follows a protracted period of maturation for high frequencies and reaches adult-like feature by 10-12 years of age.

Sweep frequency impedance measures in young infants: developmental characteristics from birth to 6 months

OBJECTIVE

International Journal of Audiology To study the developmental characteristics of sweep frequency impedance (SFI) measures in healthy infants from birth to 6 months.

DESIGN

All infants were assessed using high-frequency tympanometry (HFT), distortion product otoacoustic emission (DPOAE) and SFI tests. SFI measures consisted of measurement of resonance frequency (RF) and mobility (ΔSPL) of the outer and middle ear. A mixed model analysis of variance was applied to the SFI data to examine the effect of age on RF and ΔSPL.

STUDY SAMPLE

Study included 117 ears from 83 infants of different age groups from birth to 6 months.

RESULTS

The mean RF of the outer ear increased from 279 Hz at birth to 545 Hz at 4 months, whereas mean ΔSPL of the outer ear decreased from 7.9 dB at birth to 3.7 dB at 4 months of age. In contrast, the mean RF and ΔSPL of the middle ear did not change significantly with age up to 6 months.

CONCLUSIONS

Developmental characteristics should be considered when evaluating the function of the outer and middle ear of young infants (≤6 months) using the SFI. The preliminary normative SFI data established in this study may be used to assist with the evaluation.