"American exceptiono-isolationism isn't arrogance, it's a cognitive bias impressed on us from kindergarten when we learn that there are only two languages in the world, English and Everything Else."

Actually the French suffer from this as well, thinking that every language has the rhythm of French, and only stressing the last syllables.

Learning the accent first is an insteresting trick.

But what it seems to me is that the biggest disadvantage of learning as an adult is the exposure to the new language.

Adults, by necessity (and lazyness) shy themselves of exposure to new languages, they also don't have the environment around them to support it (watching cartoons on TV, school kids talk a lot more amongst themselves and/or are paying attention to classes, etc)