It is well known that a person who has been raised in Japan and whose mother tongue is Japanese cannot tell the sound r from the sound l. If such a person were to hear the sentences He likes to read and He likes to lead taken out of context, he would most likely not be able to tell them apart. To him, both sentences would sound the same, because in his early youth his brain became accustomed to the Japanese language, in which there is no difference between the two sounds. Similar peculiarities in perceiving the differences between sounds also occur in other language environments. The Spanish and the French distinguish the sounds b and p in a different way than the English. What sounds as a b to a Spanish person, would sound as a p to an English person. Meanwhile a Thai person would hear three sounds in b and p where English-speakers hear only two.
The basic units of verbal sound are called “phonemes”. Every language has a set of such units, but none can include an exhaustive range of phonemes, covering the full scope of possible sounds the human mouth can make. The structure of the brain which stores the phonemes any person is able to hear becomes fixed very early in life. Most people can therefore only make out the basic sounds they have heard in their first linguistic environment.
Suckling on consonants
We all know that little children immediately pick up the language of the environment in which they are being raised, while later one has to try much harder to learn a new and unfamiliar language. Why is there such a difference? Would it be possible to activate the ability of spontaneous language acquisition later in life? Questions about how the brain acquires and understands and then uses a language have always fascinated scientists in this field of research.
Because it is impossible to ask babies whether they can tell the difference between, for example, read and lead, scientists have come up with a great many alternative methods to test whether infants can differentiate between individual sounds, and find out when they start to lose this ability. They created, for instance, an artificial breast which did not produce milk when a baby suckled on it, but instead emitted sounds. The more the babies sucked this speaking breast the more distinct sounds it produced, and the children were almost as pleased by this as if they were actually being fed.
However, if the children could only draw a single repeated sound out of the breast, they would eventually tire of sucking on it. When the sound changed, though, they would start sucking more actively again. It was this change in the intensity of sucking which revealed that children could tell the difference between two sounds, otherwise such a reaction would not have occurred at all. This made it possible to observe whether little children could differentiate between the sounds r and l, despite the fact that they were being raised in the Japanese language environment.
At first, scientists assumed that the children would not be able to detect the subtler differences between individual sounds, but that they would gradually learn to do so as they grew up. Surprisingly, they discovered that in fact the truth was just the opposite. Even babies of no more than a month old babies from an English language environment were able to distinguish all the phonemes that were characteristic of the English language. These babies had already developed an English-language framework within which they could tell the difference between all the different r sounds and all the different l sounds. They could not however detect the differences within both individual groups of sounds, even though they were pronounced by different speakers.
The surprises kept on coming. When the research team tested babies from other language environments, they found out, for example, that Mexican children could easily distinguish between the different sounds of the English language. Similarly, Japanese babies had no difficulties with telling apart the sound r from the sound l, despite the fact that their parents were unable to do so.
Babies can speak all languages
Infants can distinguish between phonemes of all the existing languages of the world even when they have never heard a given language before. It makes no difference whether the sounds are characteristic of French, English, Chinese or Slovenian, infants have no difficulties telling them apart regardless of who pronounces them, be it a man, a woman or a child. Babies have an inherent aptitude for learning languages. In fact, they have a sort of universal talent for learning any of the approximately 6000 languages that still exist today.
It is also important to emphasize that a child does not merely distinguish individual sounds like a computer detector which can be set to detect the difference in the frequency of two consecutive sounds. Children are able to correctly categorize sounds by classifying them into groups on the basis of which words are formed. When born, every child functions like a sort of universal receiver that can acquire any language. The key question that arises is why babies, which are born as universal linguists, later become specialized in their language only, and lose the ability to differentiate between the phonemes of other language environments.
Because the breast imitation test was not so effective with older infants, scientists developed other methods to monitor how babies respond to different sounds when they pass six months of age. Today, electric sensors are used for this purpose, attached to the child’s head in a sort of hat to measure minute differences in brain activity. These devices can detect when the child notices or fails to notice a difference between two phonemes.
In Japanese children, researchers discovered that they could still easily distinguish between the English r and l at seven months, but would lose this ability only three months later. Nine-month-old Japanese children could no longer tell the difference between the two sounds while American children of the same age actually became more observant of this difference. Similar research conducted on Canadian children revealed that at six months of age they could hear distinctions between the phonemes of exotic languages which were inaudible to their parents and twelve-month-old peers. By the age of one, however, children lose this ability to learn perfectly any language they hear. Instead their brains adapt to deepen and broaden their ability in the language of their everyday environment.
Scientists have observed a similar adaptation in deaf children. Deaf infants go from being able to acquire the elements of any sign language whatsoever to developing a more complex facility with a single system. A number of research paths thus led to the conclusion that all children at about the same age become much more specialized in distinguishing basic parts of speech. Research has shown that once they have lost their ability to differentiate between all phonemes, children begin to learn the language of their environment more rapidly than those who remain sensitive to the sounds of languages for a longer period of time. The reason for this is that communication is substantially easier when the brain focuses on the differences important for conveying information and ignores everything else.
The time when children start losing the ability to tell the sounds of foreign languages apart approximately coincides with the time when they redirect their attention from sounds to words. That is when they first become familiar with all the possible words in their language environment. Researchers have found that nine-month-old children prefer listening to sets of sounds which combine in the same ways that sounds usually combine in their native language, even if those sounds do not form actual meaningful words in that language.
Direct contact is important
The latest research also puts fascinating emphasis on a child’s need for direct personal interaction in learning a language. The importance of personal contact emerged in an experiment to find out whether exposing children to a foreign language could prolong their early ability to differentiate between the full range of phonemes.
A number of nine-month-old infants were separated into four groups. All of the children had been raised in a purely English-speaking environment. Over the course of a couple of weeks, the children in the first group played with Chinese teachers who communicated with them solely in Chinese. The second group watched the Chinese teachers on video, while the third group only listened to them and the fourth group had no contact with them whatsoever.
The experiment showed that only the children who had been in direct contact with the teachers preserved their ability to tell Chinese phonemes apart later on. Their peers in the control groups who had only listened to the teachers or watched them on video could later distinguish the foreign phonemes no more than the children who had neither seen nor heard the Chinese at all.