06 Nov 2009

Babies cry in their mother tongue

Infants who are just a few days old cry with intonation patterns that reflect the language spoken by their parents, new research shows.

The conclusion drawn by German researchers is that foetuses are listening closely to their mothers during the last trimester of pregnancy, laying the groundwork for learning language even before they're born.

By analysing the sounds of newborn cries, researchers found distinct differences in the intonation patterns of German and French newborns. Put another way, German babies cried in a recognisably "German" way, while French newborns were decidedly "French" in their crying patterns, according to the study published in Current Biology.

Cry melodies
"The dramatic finding of this study is that not only are human neonates capable of producing different cry melodies, but they prefer to produce those melody patterns that are typical for the ambient language they have heard during their foetal life, within the last trimester of gestation," senior study author Kathleen Wermke, of the University of Wurzburg, said in a news release from the journal's publisher.

Janet DiPietro, a developmental psychologist and associate dean for research at the Johns Hopkins Bloomberg School of Public Health, called the study "fascinating."

"It's entirely plausible," DiPietro said. "German and French differ in certain fundamental properties. The fact that researchers can show the foetal cry also differs on those fundamental properties is pretty interesting and compelling."

Mom's voice most influential
Sorry, Dad. Most of the influence is probably coming from mom, DiPietro said. Even though the foetus can hear their father's voice - in fact, deeper-pitched sounds such as the male voice travel better through the abdomen than higher-pitched female voices - the mother's voice is also transmitted internally, through the vibration of her vocal cords.

"We know that the maternal voice is the most salient external stimulus to the foetus," DiPietro said.

The study
German researchers recorded the cries of 60 newborns born to either French- or German-speaking parents. The babies were three to five days old.

A sound pattern analysis revealed unmistakable differences in the newborns' "cry melodies." While French newborns tended to cry with a rising (low to high) contour, German newborns had a falling (high to low) inflection.

The patterns are consistent with the inflection patterns of the two languages, according to the study. French is characterised by a rising pitch toward the end of words and many phrases, while German is marked by falling pitches.

Memories in the womb
Previous research has shown foetuses are able to form memories in the womb that are important for early learning, said Kenneth Gerhardt, a professor of audiology and senior associate dean of the graduate school of the University of Florida.

A prior study noted a change in foetal heart rate when listening to a familiar voice. Shortly after birth, other studies have shown babies are more attentive to their mother's voice than other voices, supporting the idea that the foetus develops memories of the maternal voice in utero.

"This is a valid study and a clever way to look at the memories that are formed in utero," Gerhardt said. "The researchers are correct in stating these memories probably occur at the beginning of the third trimester of pregnancy. It's at that point in time the auditory system just begins to respond to acoustic signals."

Mimicking vowel sounds
Earlier studies have shown 12-week-old infants can mimic the vowel sounds of adult speakers. But younger babies don't yet have the muscle coordination to produce the level of vocal control necessary to do that, according to the study.

Mimicking melody contour is simpler.

"Imitation of melody contour, in contrast, is merely predicated upon well-coordinated respiratory-laryngeal mechanisms and is not constrained by articulatory immaturity," the researchers wrote. "Newborns are probably highly motivated to imitate their mother's behaviour in order to attract her and hence to foster bonding."

The concept that foetuses can learn does not support playing classical music for your unborn child or the use of "foetal learning systems," which are marketed as a way to give babies a head start by playing certain sounds through the abdomen.

"We have known for some time the foetus is capable of some learning, but it doesn't mean you should teach them stuff," DiPietro said. "That's the leap people make. But among all of us that do foetal research, we are unanimous that it's a terrible idea to put speakers on your abdomen and play stimuli to your foetus. There is no evidence they work, and we would guess they could even harm development by disrupting foetal sleep."- (Jennifer Thomas/HealthDay News, November 2009)