The development of human fetal hearing.

Blink-startle responses to vibroacoustic stimulation were monitored ultrasonically in human fetuses of known gestational age. Responses were first elicited between 24 and 25 weeks of gestational age and were present consistently after 28 weeks. Defining the developmental sequence for audition provides a foundation for diagnosing deafness and recognizing aberrant responses antenatally.