Funny side note: My friend had a theory one time that the only real difference between US and UK/AUS accents is caused by the degree to which people open their mouths. When you watch a Brit actor, their mouth doesn't open nearly as much as a US actor. When I try to fake a Brit accent, I even notice my mouth doesn't open as much. That's why, when you hear a Brit/Aussie singer perform, you rarely can notice their accent. They sound more like a USian. Because when you sing, you really open your mouth and belt it all out.
This might also be a more literal reason why the world views the US as a bunch of raving bigmouths as well.
