Spontaneous and evoked otoacoustic emissions in preterm neonates.

Spontaneous (SOEs) and evoked otoacoustic emissions (EOEs) were recorded in a group of preterm neonates (N = 134 ears) in order to study the basic properties of SOEs and EOEs as a function of gestational age. In the study, it was found that: 1. EOEs were recorded in 93% of the tested ears; 2. SOEs were recorded in 61% of the tested ears; 3. there were no statistically significant variations of EOE amplitude with gestational age; 4. EOE spectrum did not vary with age; and 5. the two main factors influencing EOE amplitude were the SOE presence and the fast Fourier transform spectrum, especially the lower limit of the spectrum. Thus, the maturation of outer hair cell properties appears to be complete at 32 weeks of gestational age. Because a number of infants at risk for hearing loss are preterm babies, screening for EOEs, an objective, rapid, and nontraumatic technique, may prove useful in evaluating peripheral auditory dysfunction in preterm neonates.