Meryn Stol voted up this answer. Jeannine van der Linden Because if you cannot hear a sound, you cannot duplicate it. While young children do not have this problem, adults do: sounds and sound combinations which do not have meaning in the native language are simply not heard by older speakers of that language. To a native speaker of English the Dutch words maan and man sound exactly the same, as do huis and house. Fixing this requires first relearning to hear which is a fundamental proposition. It is a case of lazy brain, not lazy mouth. *The Dutch are all laughing now as in fact they do not even sound similar. See question on Quora - Meryn Stol