Whether it's volume, content, or exaggerated vowels, you just have to overhear an American tourist while overseas to notice that Americans have a distinct way of speaking. But many Brits (mistakenly) think watching American film and television makes them trained in an American accent.
One English reporter, determined to be better than a Hollywood wannabe, decided to get top professional training from accent-coach-to-the-stars Barbara Berkeley. Berkeley, who has trained the likes of Brad Pitt and Gwyneth Paltrow, offered these simple technical steps for learning to speak like an American: Widen your mouth like you would making the "ee" sound in "weed." Smile, to place the voice towards your nasal resonator. Position your tongue further up in the mouth, rather than against the ridge behind the top teeth. And finally, let yourself go!
If you learn better by example, I've rounded up some clips of foreign actors speaking "American." Tell me, out of Hugh Laurie, Nichole Kidman, Ralph Fiennes, and Cate Blanchett, who does the best American accent? And what characteristic makes a speaker sound quintessentially American, anyway? You know?