On language and colic

A correspondent writes to ask whether singing to her baby will help when it's colicky.

The power of song over babies has long been recognized. The word lullaby has been in the English language since the Middle Ages - one of several, such as rockaby and hushaby, which show how generations of mothers and caretakers have helped their children fall asleep through music.

But music has greater power than this. As any adult knows, music has the power to engage all the emotions - from excitement to relaxation, from tears to laughter. Its power to calm is well recognized. The dramatist William Congreve summed it up in a famous quotation: 'Music hath charms to soothe a savage breast, to soften rocks, or bend a knotted oak'. But if the breast of adults, then why not the tummies of children?

Why does music have such a power over us? And why, in particular, does it have such an influence on tiny babies? A huge amount of research in infant perception over the past few decades has begun to reveal the answers. And it begins before birth, in the womb.

The womb is actually quite a noisy environment, and from around 30 weeks gestation the ears of the foetus are sufficiently well formed to enable it to hear what is going on. Indeed, the tiny little bones inside our ears, which transmit sound to our brain, are already fully formed by the time we are born. During some types of gynaecological examination, researchers have inserted a tiny microphone, called a hydrophone, into the uterus, enabling them to hear what the foetus can hear. And what the foetus hears is a great deal of background noise - the mother's heartbeat, the blood sloshing around the arteries, tummy and intestine rumbles, voices and loud noises from outside - and, above all, the mother's voice resonating through her tissues, bones, and fluids. The foetus is asleep a lot of the time, but when awake, its heart rate slows when the mother is speaking - the first evidence of a calming response.

It can't hear everything perfectly, of course. The effect is a bit like listening to a voice with cotton wool in our ears. The voice sounds distant and muffled. But there are certain things the foetus can hear very clearly. It can hear the intonation, or melody, of the mother's voice, and it can hear the loudness and rhythm of her speech. Sound and movement combine: when she laughs, the foetus can be seen to bounce around.

Once the baby is born, people have performed experiments which demonstrate just how much the foetus has heard. Researchers monitor the baby's heart-rate, the amount of cortisol in its saliva, the way it turns its head, the length of time it looks in a certain direction, or the rate at which it sucks on a special kind of nipple. The idea is that if a baby recognizes something, or is specially interested in something, then its heart-rate or saliva cortisol content will alter, or it will turn its head towards a stimulus, or it will look at a stimulus for longer, or it will suck faster.

And this is the sort of thing they've found. Newborn babies, even just a day old, prefer their mother's voice to that of a stranger. The show more interest when hearing their native language as opposed to a foreign language. And if the mother has told the foetus a particular story, during her pregnancy, they show a preference to that compared with an unfamiliar story.

The effect of music emerges too. One study played the same tune to a group of mothers every day throughout pregnancy; another group of mothers didn't hear the tune. When all the babies were born, the tune was played to them. The changes in heart-rate, movement, and general alertness of the 'musical' babies showed clearly that they recognized the tune. To check that it wasn't just a general response to music, the researchers played the babies a different tune, but they didn't react to it. Nor did they react to it when they heard the same tune played backwards!

There seems to be something special about the music of the voice. From the moment the baby is born, the mother - and other caretakers too - start talking to the baby in an unusual manner. That's what we call 'babytalk'. One of its most noticeable features is the way the voice ascends and descends throughout its whole pitch range - almost like singing in speech. And the exaggerated tones stay throughout the first year of life. The mother's voice is higher in pitch, and she speaks more slowly, when addressing the baby than when talking to others, and she is emotionally much more expressive. The effects can be clearly heard when playing simple games, such as peep-bo or round-and-round-the-garden. Games like this also draw attention to the importance of sensory reinforcement - sound, vision, touch, and movement all combine to create the maximum effect - 'and TICKLE him under there!!!'

Not surprisingly, then, the first features of the mother's language that the baby learns to reproduce are its intonation and rhythm. If we record babies' early vocalizations, at around a month or so of age, we cannot tell which language they are learning. Nor can we tell from their cooing or babbling. But at around 9 months the vocalizations start to sound 'shaped', and it's possible to distinguish babies who are learning English from those learning French from those learning Chinese, and so on. This is long before they learn any words, so what is it that we notice? The rhythm and intonation of the languages. The English baby is vocalizing with a 'tum-te-tum' rhythm. The French baby with a 'rat-a-tat-a-tat' rhythm. The Chinese baby with a sing-song rhythm. Why intonation and rhythm? It's no coincidence that these were the very features first perceived in the womb.

Melody, whether of speech or music, seems to be especially significant. Singing holds a special place in the emerging world of babies. They notice it. In one study, six-month-old infants were presented with pictures of their mother while she was singing and while she was speaking. They looked for longer at the singing one, and were less active while they did so, suggesting that they were paying more attention. Other studies show that infants can recognize melodies, even when they are presented at different pitch levels (sung higher or lower) or sung at different speeds. The melodic contour is the thing. Maternal singing, especially, is critical. It's different from normal singing, in that it is slower, higher in pitch, and emotionally more expressive - just like maternal speech.

Singing also simplifies vocal behaviour: words tend to be shorter, sounds are clearer and repeat more often, and they often rhyme. The value of repeated sounds and rhyme is well established, both for children's speech development and also later on in relation to reading. Repeated sounds are a major feature of babbling (babababa, dadadada); early words use them (mama, papa); and parents instinctively repeat syllables (doggie, bunny). Nursery rhymes work so well because they combine several effects - clear rhythm, repeated sounds, and rhyme. The effect of rhyme on babies can be measured from around 7 months. Primitive spontaneous singing can be observed in babies from around 9 to 12 months. When combined with vision, touch, and movement - as when telling a nursery rhyme while rocking a child in a cot or playing on a knee - the effect is extremely powerful. If the baby can see the singer, the effect is even more enhanced.

Maternal singing has a moderating effect on the emotional state of the baby. There are now many reports of music being used to calm sick babies. Music therapy is routine in many premature baby units. It seems to provide them with a safe and positive sensory experience. There is a bonus in that maternal singing seems to have a calming effect on the mothers too. Exploiting the melody and rhythm of song and speech would thus seem to be an ideal way of helping mothers to soothe their babies when need arises.