OK, I've finally decided to write something. In my last post, I alluded to a reason for children being able to eventually speak their new language without an accent, whereas those a little older typically get stuck with an accent. Now I will tell you why that is. It is just my idea, though. So take it or leave it.
First of all, I should mention that we are talking about immigrant children. They are brought by their parents to a new country and they have to learn a new language.
What is the difference between the younger children and the older children? It is not physical. It is not that the older children or even the adults are too old to be able to speak without a foreign accent. So what is the difference?
Well, what is expected is what is different! The older you are, the more you are expected to start speaking and using your new language skills. The younger you are, the less that is expected of you. If you are only 8 years old, nobody is going to ask you to explain why the president's plan is doomed from the outset. No, you are just going to go to school, tell people your name and that is about it. You'll come home, watch hours and hours of TV, go to school and listen to your teachers and classmates talking. An 8 year old is not going to jump right in and start hacking away at the language. The younger you are, the more time you have to absorb the sounds of the language.
A high school student is at a much higher social level than an elementary school kid. The high schooler will be asked many more questions and fellow classmates will be interested in talking and finding out about the new foreign kid on the block. The high school student will be interacting and involved to a much deeper degree, while the younger brother learns how to play tag and yell, "You're it!"
So now you can see that the kids don't have any magic. They just have more time before they need to talk. They listen and learn how the language sounds. In a year, maybe two, the younger child has absorbed much more of the language and done less thinking. The older child has done much more thinking, speaking, and reinforcing bad habits.
It's essential to work on pronunciation before you get used to speaking. Lots of listening helps. At least do 2 weeks of listening before ever attempting to speak. If you really work on pronunciation in the beginning, then I think the maximum listening-only period would be about 2 months. In the beginning of language learning, the only important thing is concentrating on the sounds (pronunciations) of the language. After that, concentrate on reproducing those sounds perfectly.
Once you have pronunciation down perfectly, it will be your second nature. It won't require any extra effort.