Longitudinal Development of Wideband Absorbance and Admittance Through Infancy

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.

Wideband absorbance for the assessment of pressure equalizing tubes patency in children

OBJECTIVES

To analyze the feasibility of using wideband absorbance to verify the patency of pressure equalizing tubes (PETs) in clinical practice and to present the response pattern of this measure for ears with patent PET.

METHODS

This observational case-control type study evaluated 48 ears of 30 children with severe or profound hearing loss, aged 10-44 months, of both sexes. The subjects were subdivided into two groups: 24 ears with Sheppard type PET (experimental group - EG) and 24 ears with normal middle ear (control group - CG), paired with the EG, according to age, sex, and ear evaluated. To obtain the wideband absorbance, a Middle-Ear Power Analyzer, version 5.0 (Mimosa Acoustics), was used, and absorbance values for pure tone and chirp stimuli were analyzed.

RESULTS

There was no influence of ear (right or left) on the measurements obtained. The EG showed higher absorbance values at low frequencies. Although the two stimuli made it possible to identify the difference in acoustic transfer function between the groups studied, compared to pure tone, the chirp stimulus allowed identification of differences in a higher number of frequencies.

CONCLUSIONS

Ears with a patent PET present an acoustic transfer pattern that differs from that obtained for normal middle ears, with a higher absorbance at low frequencies. Both pure tone and chirp stimuli can be used to identify such differences, nevertheless, the use of chirp stimulus is recommended, since it allows differentiation over a wider frequency range.

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.

Diagnosing Middle Ear Dysfunction in 10- to 16-Month-Old Infants Using Wideband Absorbance: An Ordinal Prediction Model

Purpose The aim of this study was to develop an ordinal prediction model for diagnosing middle ear dysfunction in 10- to 16-month-old infants using wideband absorbance. Method Wideband absorbance, tympanometry, and distortion product otoacoustic emissions were measured in 358 ears of 186 infants aged 10-16 months (M _age = 12 months). An ordinal reference standard (normal, mild, and severe middle ear dysfunction) was created from the tympanometry and distortion product otoacoustic emission results. Absorbance from 1000 to 5657 Hz was used to model the probability of middle ear dysfunction with ordinal logistic regression. Model performance was evaluated using measures of discrimination (c-index) and calibration (calibration curves). Performance measures were adjusted for overfitting (bias) using bootstrap resampling. Probabilistic and simplified methods for interpreting the model are presented. The probabilistic method displays the probability of ≥ mild and ≥ severe middle ear dysfunction, and the simplified method presents the condition with the highest probability as the most likely diagnosis (normal, mild, or severe middle ear dysfunction). Results The c-index of the fitted model was 0.919 (0.914 after correction for bias), and calibration was satisfactory for both the mild and severe middle ear conditions. The model performed well for the probabilistic method of interpretation, and the simplified (most likely diagnosis) method was accurate for normal and severe cases but diagnosed some cases with mild middle ear dysfunction as normal. Conclusions The model may be clinically useful, and either the probabilistic or simplified paradigm of interpretation could be applied, depending on the context. In situations where the main goal is to identify severe middle ear dysfunction and ease of interpretation is highly valued, the simplified interpretation may be preferable (e.g., in a screening clinic that may not be concerned about missing some mild cases). In a diagnostic clinical environment, however, it may be beneficial to use the probabilistic method of interpretation.

Swept-Tone Stimulus-Frequency Otoacoustic Emissions in Human Newborns

Several types of otoacoustic emissions have been characterized in newborns to study the maturational status of the cochlea at birth and to develop effective tests of hearing. The stimulus-frequency otoacoustic emission (SFOAE), a reflection-type emission elicited with a single low-level pure tone, is the least studied of these emissions and has not been comprehensively characterized in human newborns. The SFOAE has been linked to cochlear tuning and is sensitive to disruptions in cochlear gain (i.e., hearing loss) in adult subjects. In this study, we characterize SFOAEs evoked with rapidly sweeping tones in human neonates and consider the implications of our findings for human cochlear maturation. SFOAEs were measured in 29 term newborns within 72 hr of birth using swept tones presented at 2 oct/s across a four-octave frequency range (0.5–8 kHz); 20 normal-hearing young adults served as a control group. The prevalence of SFOAEs in newborns was as high as 90% (depending on how response “presence” was defined). Evidence of probe-tip leakage and abnormal ear-canal energy reflectance was observed in those ears with absent or unmeasurable SFOAEs. Results in the group of newborns with present stimulus-frequency emissions indicate that neonatal swept-tone SFOAEs are adult-like in morphology but have slightly higher amplitude compared with adults and longer SFOAE group delays. The origin of these nonadult-like features is probably mixed, including contributions from both conductive (ear canal and middle ear) and cochlear immaturities.