Wideband reflectance in neonatal intensive care units

Wideband reflectance (WBR) provides important information about middle ear function and can explain variations in how the middle ear receives, absorbs, and transmits sound energy across a wide range of frequencies. However, as of yet, few normative studies have been published to guide clinicians in the practical applications of WBR. WBR has been measured more extensively in well babies than in neonatal intensive care unit (NICU) babies, who have significantly higher incidence of otitis media with effusion (OME).

The goal of this study was to explore the characteristics of the middle ear while using energy reflectance (ER) and normalized admittance in NICU babies who passed automated auditory brainstem response (AABR) and evoked otoacoustic emission (EOAE) hearing screening criteria and to compare these characteristics to patterns in normal hearing adults. This study was done to identify ways to implement WBR so it could improve hearing assessment in newborns.

Thirty-one neonatal intensive care unit (NICU) babies with an average gestational age (GA) of 37.8 weeks (range: 32-51 weeks) and 56 adults with normal hearing between the ages of 18 and 32 years served as subjects in this study. NICU babies and adults were tested using multifrequency tympanometry (MFT) and WBR.

WBR can be obtained on what appears to be a majority of NICU babies without other abnormal findings. Maximum absorption of the incident energy appears to occur at a narrower range of frequencies in normal NICU babies in comparison to normal hearing adults. This range becomes even narrower in NICU babies who fail EOAE screening. In most NICU babies who failed EOAE screening, ER values were closer to 1 (most incident energy is reflected) at a frequency below 3000 Hz. The measurements of normalized acoustic admittance may also be very useful and may supplement ER and tympanometric data in evaluating middle ear status.