ABSTRACT

Objectives The overall goal of this study was to assess tympanometric and ambient wideband acoustic immittance (WAI) tests and wideband acoustic reflex thresholds (ART) in well-baby and newborn intensive care (NICU) cohorts with three specific objectives: 1) Assess predictive accuracy for WBT and ART for conductive dysfunction in ears referring on the first or second stages of newborn hearing screening; 2) Identify inadequate tests likely due to probe blockages or leaks; and 3) Assess prediction models separately for well-baby and NICU screening outcomes.

Design Prospective, observational study of full-term (n=514) and premature newborns (n=239) recruited from well-baby and NICU nursery birth hospital newborn hearing screening program. Wideband tympanometry, ambient absorbance, and acoustic reflexes were tested after Stage 1 transient otoacoustic emissions (TEOAE) screening. The reference standard for Pass or Refer groups was initially defined on the stage 1 TEOAE test result. Pass or Refer groups were then reassigned based on the stage 2 screening ABR for those who referred at Stage 1, and all NICU infants. Multivariate models were developed using reflectance and admittance variables to predict conductive dysfunction relative to the screening reference standard in a randomized sub-group of subjects at Stage 1 and Stage 2 screening. Classification accuracy was evaluated on a second, independent sub-group. Individual tests were classified as having inadequate probe fits if they had excessively low values of sound pressure level or susceptance (leak) or absorbance (blockage).

Results Differences in ambient absorbance for Pass v. Refer screening groups revealed the greatest differences and effect sizes occurring in frequency bins between 1.4-2 kHz. Screening failure at both Stage 1 and 2 was most accurately predicted by models using ambient absorbance and power level variables at frequencies between 1-2.8 kHz, including ARTs. Tympanometric admittance variables at the positive-pressure tail for frequencies between 1-2.8 kHz in combination with the ART were more accurate predictors than those at peak pressure or the negative-pressure tail. Multivariate models generalized well to an independent group of infants at both Stage 1 and 2 for both the ambient and tympanometric models. Ambient tests revealed more inadequate tests than tympanometric tests, primarily due to blocked probe tips. Exclusion of ears to detect probe leaks or blockages slightly improved the ambient prediction models, but did not affect tympanometric models.

Conclusion Wideband acoustic reflex tests improved all models for ambient and tympanometric absorbance. Multivariate prediction models developed for WAI tests were repeatable in an independent group of well and NICU infants, suggesting that the results are generalizable to these populations. Detection of probe blockage or leaks slightly improved prediction for ambient measures. Pressurized tests have the advantage of ensuring probe seals due to the need for a hermetic seal, thus are useful to ensure adequate probe insertion.

Competing Interest Statement

D.H.K. has an interest in the commercial development of devices to assess middle-ear function.

Funding Statement

This study was funded by grants R01 DC010202 and ARRA supplement R01 DC010202-2 awarded from the National Institute on Deafness and Other Communication Disorders. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The Institutional Review Boards of Cincinnati Children's Hospital Medical Center and Trihealth gave ethical approval for this work.

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List of Abbreviations and Term definitionsaSuffix appended to indicate ambient-pressure variablesAaAbsorbance at ambient pressureABRAuditory Brainstem ResponseAICAkaike Information CriterionAptAbsorbance at positive pressure tympanometry tailARTAcoustic Reflex ThresholdASRAcoustic Stapedial-muscle ReflexAtppAbsorbance at Tympanometric Peak PressureAUCArea Under the Receiver Operating Characteristic CurveBBNBroad Band NoiseBICBayesian Information CriterionDGroup delay (phase expressed in time units across frequencies)DPOAEDistortion Product Otoacoustic EmissionsGLMGeneral Linear ModelIQRInter-Quartile RangeNHSNewborn Hearing ScreeningNICUNewborn Intensive Care UnitNNNumber NormalntSuffix appended to indicate negative-tail tympanometric variablesPCAPrincipal Component AnalysisPntPressure at negative pressure tympanometry tailPptPressure at positive pressure tympanometry tailptSuffix appended to indicate positive-tail tympanometric variablesROCReceiver Operating CharacteristicSNHLSensorineural Hearing LossSNRSignal-to-Noise RatioSPLSound Pressure LevelTEOAETransient Evoked Otoacoustic EmissionsTPPTympanometric Peak PressureWAIWideband Acoustic ImmittanceWBTWideband TympanometryWBNWell-baby nurseryWLAbsorbed Power LevelYISusceptance or imaginary part of admittanceYMAdmittance MagnitudeYPAdmittance PhaseYRConductance or real part of admittance