Spontaneous otoacoustic emissions in neonates and effect of contralateral white noise stimulation

Neonates younger than the age of 12 weeks (10 full-term, 20 preterm) had an audiological assessment consisting of brainstem audiometry, tympanometry, transiently evoked otoacoustic emissions, and spontaneous otoacoustic emissions with contralateral white noise stimulation. Results from brainstem audiometry, tympanometry, and transiently evoked otoacoustic emissions suggested normal middle ear function and normal cochlear function. All full-term neonates had multiple spontaneous otoacoustic emissions, and contralateral white noise stimulation resulted in enhancement of emissions in 80%, whereas in 20% the emissions were suppressed. In preterm neonates, spontaneous otoacoustic emissions were present in 55%. These emissions were mostly solitary and, in 64%, showed suppression with contralateral white noise stimulation. Embryological data taken into consideration suggest that the pattern of spontaneous otoacoustic emissions in preterm neonates is more likely related to immaturity of the central auditory pathway rather than the cochlea.