Responses of neonates to parents' and others' voices.

Infants stimulated with 8-s recordings of speech and voices reading numbers showed a discrimination between their own mothers' and alien voices. In general, the infants' heart rates rose more in response to their mothers' than to an alien voice. However, infants tested less than 24 h after birth responded with significant heart rate deceleration to the mother's spontaneous speech and to the mother reading numbers. Response to the father's voice was also deceleration but to all alien voices was acceleration. Older infants' responses also tended to be acceleratory to most stimuli. Results support the suggestion that sounds which are repeatedly experienced before birth (especially the mother's voice) become familiar to the fetus so that the neonate responds selectively by orienting to them during the first few hours after birth.