Changes in transient-evoked otoacoustic emissions in the first month of life.

OBJECTIVE: Current Joint Committee on Infant Hearing guidelines recommend the use of transient-evoked otoacoustic emissions (TEOAEs) as a screening tool to identify hearing loss for newborns cared for in the well-baby nursery. Newborns who do not pass the TEOAE screen before leaving the hospital are typically rescreened as outpatients by 1 mo of age, at which time, approximately 50 to 70% pass screening criteria. To better understand why many infants are referred at initial screening but pass at the rescreening, more complete knowledge of developmental differences in the TEOAE levels, noise floor, or a combination of both for infants who pass and fail birth screening is needed. In addition, it has been shown that infants with occluding ear-canal debris are more likely to not pass TEOAE screening at the hospital than those without occluding ear-canal debris. This study explores whether changes in TEOAE levels in half-octave frequency bands are related to changes in ear-canal debris over the first month of life.

DESIGN: Seventy-nine neonates from a well-baby nursery had their hearing screened before leaving the hospital and again at approximately 1 mo of age. All participants passed the follow-up screening. Overall TEOAE levels and levels in half-octave frequency bands centered at 1.5, 2, 3, and 4 kHz were measured. Judgments of ear-canal debris were made by otoscopy and were rated using one of three categories at both visits.

RESULTS: TEOAE levels in infants significantly increased from birth to 1 mo of age across all frequencies tested, regardless of whether they passed or failed the screening at birth. The increase in TEOAE level was frequency dependent, with the greatest increases occurring in the highest frequency bands. No significant correlation between debris change and frequency-specific changes was found for either ear. Infants who failed the screening at birth but who subsequently passed at 1 mo of age had significantly lower TEOAE levels at the rescreening than did infants with passing TEOAE levels at birth. However, pass/fail status at birth was only a weak predictor of TEOAE levels at 1 mo of age.

CONCLUSIONS: The increase in TEOAE levels during the first month of life is frequency dependent, with greater increases occurring at higher frequencies. Increased TEOAE levels were not associated with changes in ear-canal debris.