The effect of sounds on newborn infants under stress

Five-day-old infants' responses to heelstick stress were assessed with behavioral and physiological indices. The subjects were divided into three groups: the WHITE group (n = 35), who were presented with white noise during the heelstick; the HEART group (n = 33), who were presented with recorded heartbeat sounds during the heelstick; and the CONT group (n = 34), who were presented with no sounds. Both heartbeat sounds and white noise were presented to infants at 85 dB. The CONT group showed more reactive behavioral responses and adrenocortisol release in saliva than the other groups. Presenting sounds to newborn infants in this stressful situation had a calming effect.