Spectral changes to sound exposure when preterm infants transition from the incubator to an open crib

Children born preterm are at risk for speech and language developmental delays and disorders. It has been proposed that adverse auditory exposures during stay in the neonatal intensive care unit (NICU) may contribute to this risk, as it is well-established that the preterm infant’s developing auditory system is sensitive to acoustic input during this time. While reduced speech exposure, noxious noise levels, and excessive silence in the NICU are of concern, another potential cause for concern is abrupt changes in auditory exposure during NICU stay. Our previous data indicate that NICU incubator walls have a low-pass filtering effect, attenuating external sounds at frequencies above 200 Hz. However, internal sounds generated by the incubator or other life-saving devices still produce noise exposure. Furthermore, when infants transition to an open crib from the incubator based on improved overall health, they may be at risk of increased exposure to higher frequencies. Here we present spectral analyses of auditory exposure recordings made for several preterm infants throughout NICU stay. Our analysis reveals that for frequencies above 500 Hz, sound levels are significantly higher in the open crib; below 500 Hz, levels are generally higher in the incubator. These data point to yet another potentially disruptive effect of the NICU environment caused by an abrupt change in auditory exposure.