This article (behind a paywall) in the latest issue of Scientific American notes that all human languages combined have about 800 sounds, while individual languages have about only about 40 sounds. During our sensitive period of language development we master the sounds of our own language, but often lose the ability to make, or even, in some cases, to distinguish between, the sounds of other languages.
Recently, I have been trying to pick up some phrase book Hindi in preparation for a trip to India and I am surprised by how difficult it is master some of the sounds of this Indo-European language. Sam Miller in his great book Delhi: Adventures in a Megacity writes about his difficulty ordering toast in India. The word toast has been incorporated into the Hindi language, however Hindi has four different ways to pronounce T, none of them corresponding exactly to the way English speakers pronounce it. Thus, if not for the help of his Indian wife he would be unable to order this important staple.
A great excuse for Monty Python: