[Auditory perception and fetal reaction to react to sound stimulation (author's transl)].

The confirmation of techniques used to stimulate the fetus in utero led us to an exhaustive study of spontaneous intra-uterine noises and those modified by different stimuli (while evaluating the diagnosis of fetal distress with flat cardiac rhythm during pregnancy). By the use of elaborate techniques simultaneously we could appreciate the signal and analyse the information obtained and we able to show incontrovertibly that over and above the basal sound that the fetus could hear it could appreciate the mother's voice and other voices, which were perfectly audible to it but lacking in tone because the sharp frequencies were absorbed. The first results of stimulation using calibrated sounds seem to confirm that the fetus does not react to a sound stimulus when it is in a state of fetal distress, but when there is no fetal distress it does react immediately by change in the heart rate, often associated with movements. This technique, incidentally, can be used to show if the fetus can hear well in the uterus in cases of family deafness or of rubella associated with pregnancy.