Children learn a lot within the first nine years of their life, in fact, our brains are still in development until about the age of 26! So it is very important to get those skills early on in life while the brain is still really developing (around ages 0-9 and even still till the age of 26)
Encourage children to read and pronounce things clearly. Have them listen to fun books on cd. If your child is a bit older try the Harry Potter series, or if they are younger try something like, the Chronicles of Narnia, the Boxcar Children, or even Beatrix Potter if they are in to animals. If younger still, read aloud books like from Doctor Seuss, or the fun and entertaining; The Very Hungry Caterpillar.
Perhaps have them take a class on a foreign language, usually Spanish is a good one to start with. And if all else fails, take them in to a doctor who can advise and help a child in other ways than these. Hope this helps!
This doesn't necessarily have a technical term, it is best known as Musical Nationality
