Evoked otoacoustic emissions from normal newborns and babies admitted to an intensive care baby unit

Click-evoked otoacoustic emissions (OAEs) were recorded from both ears in two groups of neonates ranging in age from a few days to two months after birth. The first group consisted of 55 full-term neonates with normal developmental history and health status, including absence of middle ear disease and familial history of hearing loss. The second group consisted of 40 infants admitted to an intensive care baby unit for various pathological conditions (anoxia, prematurity, hyperbilirubinemia, meningitis). The method achieved 97% success in assessing cochlear function in the normal group; it was possible to identify a clear and reproducible response in all ears, except 3, at 70 dB SPL (i.e. approximately 30 dB nHL). The detection-threshold of OAEs was comparable to that measured in adult ears. Several babies from the second group produced no OAEs and were also tested by auditory brainstem responses (ABR): these infants demonstrated ABR thresholds higher than 30 dB nHL. OAEs provide an objective tool for a rapid and effective screening test for cochlear impairment in neonates.