CERTAIN characteristics of the human voice at normal levels have a great influence on the neonate1, and infants 1 month old can detect fine differences in speech-like sounds2,3. This enables a selective response to take place when the child meets adults. From birth, babies will turn towards the source of a sound, and this orientation to a voice helps them to learn about faces. We have also observed that infants are more interested in their mother's face when she is talking. �� 1974 Nature Publishing Group.