Check out this Ted talk by Patricia Kuhl: The linguistic genius of babies.
She shows us at 3.14 that before the first birthday the children are already beginning to screen out sounds that they do not need to communicate with their parents. At one point they are equal but for example two months later they are taking statistics on what they hear. English has a lot of r and L’s but Japanese have more intermediate sounds and the brains change to recognise their mother tongue.
She then explains more about the babies brains and how the brain responds and a machine that can track this. Great pics of the children’s brains working.
It makes me wonder why the Government are considering whether we should have compulsory language learning at KS2 when they should be saying when will be implementing language learning at KS1.