Physiological effects of sound on the newborn.

Excessive sound is an acknowledged problem in neonatal intensive care units (NICUs); however, there is relatively little objective information about the effects of sound on the newborn. The cardiovascular and respiratory systems have been the most extensively studied systems. The patterns of response in these systems may be influenced by a variety of factors, including: the intensity of the sound, the infant's behavioral state, the infant's maturity and postnatal age, and the perinatal history. This article reviews the known cardiovascular, respiratory, and other physiological effects of sound on neonates.