The ontogeny of human hearing.

The development of human hearing from the 26th week of fetal life to the third year post natal life is reviewed. The human fetus can perceive, react, and store auditory information from the 26th week of fetal life. This ability appears to play a role in the development of language. Infants by the 2nd to 3rd month of postpartum life have categorical perception for most phonemes whether or not these phonemes are native to their own language. The infant has a difference limen similar to that of the adult. The infant threshold is higher; the single-to-noise ratio is greater in infants than adults; and the infant's temporal processing is slower than that of the adult.