5. Children Acquisition
Thus far, we have been focusing on the child’s development of speech production. Now we would like to focus on the child’s development of speech comprehension. When, for example, does the understanding of speech begin and how does it relate to production?
1.2.1 Fetuses and speech input
Before dealing with newborns, let us look at research that is concerned with stimulating language development even before the child is born. Can speech sounds reach the fetus while it is still in the uterus? Benzaquen et al. (1990) put a microphone inside the uterus of a pregnant woman to see if speech sounds could reach the ear of the fetus over the background sounds of the women’s heartbeat and blood flow. The mother’s speech sounds were found to be able to reach the ear of the fetus above the background sounds. How- ever, whether the ear of the fetus is developed enough to send such signifi- cant sounds to the brain is in dispute.
In another study where loudspeakers were placed next to pregnant women, two experimental groups were presented with sound sequences in different orders: one group was exposed to /babi/ + /biba/ while the other received the reverse order /biba/ + /babi/ (Lecanuet et al., 1989). Later, after a number of presentations, the two sound sequences were played in varying orders to both groups of women and measurements were taken. Measure- ments of the fetuses’ heart rates showed a differential effect for the two groups during the testing period. The heart rate of the fetus was higher when the sequence they were trained on was played. The effects of the mother’s voice on the fetus’s intrauterine listening thus may explain post-birth listening
preferences of the neonate (newborn baby) for the mother’s voice and for the language the mother spoke while pregnant.
DeCasper and Fifer (1980) recorded mothers reading a story to their new- borns. Then their 3-day-or-younger infants were given a pacifier connected to a computer that would play recordings of the mother’s voice or of another woman’s voice. A high rate of sucking on the pacifier would activate the playing of a mother’s voice. Comparing changes on the sucking rate with the infant’s baseline rate, the researchers found that the infants sucked more in order to activate the tape with their mother’s voice than to hear the voice of another woman!
The requirement was then changed so that the infants had to suck at a lower rate than normal in order to hear their mother’s voice. The infants quickly changed to slower rates, thus demonstrating that they could distin- guish the sound of their mother’s voice and that of another woman. Locke (1993), however, suggests that the learning of the mother’s voice may actu- ally have occurred, not prenatally, but within the first 12 hours after birth when the mother was talking to the newborn. Since the measurements were taken after the 12-hour period, this could well be the case. If so, then there may not have been any prenatal learning.
It is worth mentioning that even if a fetus could hear sounds from the outside world, those sounds would have to be through the medium of a liquid in the fetal sac. That being the case, speech sounds are difficult to distinguish. How much, for example, in terms of speech sounds, can one hear when one is underwater in a pool? General sounds are all that come through. While this may be enough of a basis for a fetus later to distinguish among different voices according to pitch or loudness, it is certainly insufficient for identifying speech sounds.