Probably because Ganon raised him for a while.

Well if anything, Link can produce sound, that much is certain in his attacks. Using that, then it can be reasonably accepted that of course he talks.

no1 actually speeks in that unless u mean what they type. But if thats what u mean he must talk u just dont see what he says

Hey!...

Link probably doesn't talk, because they don't want to control your character for you too much. ;)
In some scenes, he does answer questions, but note that you get a -choice- as to how he answers them. :D