A study in the Proceedings of the National Academy of Sciences reinforces what many people had believed—babies hear what their moms say and their brains recognize these words after birth.
Researchers at the University of Helsinki in Finland looked at 33 moms-to-be, and examined their babies after birth. While pregnant, 17 mothers listened at a loud volume to a CD with two, four minute sequences of made-up words (“tatata” or “tatota”, said several different ways and with different pitches) from week 29 until birth.
The moms and babies heard the nonsense words about 50 to 71 times. Following birth, the researchers tested the all 33 babies for normal hearing and then performed an EEG (electroencephalograph) brain scan to see if the newborns responded differently to the made-up words and different pitches.
Babies who listened to the CD in utero recognized the made-up words and noticed the pitch changes, which the infants who did not hear the CD did not, the researchers found. They could tell because their brain activity picked up when those words were played, while babies who didn’t hear the CD in the womb did not react as much.
“We have known that fetuses can learn certain sounds from their environment during pregnancy,” Eino Partanen, a doctoral student and lead author on the paper, said via email.
“We can now very easily assess the effects of fetal learning on a very detailed level—like in our study, [we] look at the learning effects to very small changes in the middle of a word.”
This paper does more than simply find that babies in utero can hear; it shows that babies can detect subtle changes and process complex information.
“Interestingly, this prenatal exposure also helped the newborns to detect changes which they were not exposed to: the infants who have received additional prenatal stimulation could also detect loudness changes in pseudo words but the unexposed infants could not,” Partanen says.
“However, both groups did have responses to vowel changes (which are very common in Finnish, and which newborns have been many time previously been shown to be capable of).”
These findings build on other research conducted over the past 20 years that looks at how babies respond to sound. Minna Huotilainen, who also worked on the study, published a study in 2005 showing that fetuses can discriminate among sounds. And, in 1988 researchers found that babies who heard soap operas in utero became addicted—at least to the melodies. Babies with moms who watched soaps while they were pregnant responded to the melodic cues in the shows.
The finding support the idea that an unborn fetus can learn and remember just as well as a newborn, the researchers said. It may be worthwhile to expose babies to more sounds before they are even born.
“The better we know how the fetus’ brain works, the more we’ll know [about] early development of language,” Partanen says. “If we know better how language develops very early, we may one day be able to develop very early interventions [for babies with abnormal development].”