Yup, most people think of Mainstream US English when they think of an “American accent”–the phonetic, lexical, and morphosyntactic speech features of a white, middle- to upper-class midwesterner from a large city.
Hard to say. I depends on your first language. Still, the third-person designator is a bit tricky in the spoken form
Well, if you are talking about the rhotic or retroflex ‘r’ of American English, I believe some southern Indian languages have a very similar sound. Certain dialects of various languages around the world also have this sound, I believe, though it seems to be uncommon in the standard dialect of most European languages. I don’t believe it’s a very common phoneme, but it’s not unheard of.
Are you speaking of all the variations in all the dialects of English? Because I believe for most if not all individual English dialects the number isn’t too far off of the 13 mentioned above. Or maybe you are including dipthongs?
I just did a search and came up with this: http://faculty.washington.edu/dillon/PhonResources/vowels.html (by random chance from my alma mater). It lists the distinct vowel sounds of American and British English (Presumably the standard variety of each dialect). I counted both and with the dipthongs the American count is 17, without it is 13 (as Rigamarole estimated). The British count with dipthongs is 18 and without 11. Either with or without the number is lower than 21.
Indeed. But the movies have taught them there’s largely only one accent for the whole country.