i too have heard, that americans (i.e., US citizens) have themselves identified the mid western dialect of US english to be the most correct.. (tho i suspect NYer's would disagree!) an area stretching from Ohio, extending westward, and a bit northward, and slightly south the more west it goes.

New Englanders recognize their speach is not 'normal' (and joke themselves about 'i parked my car in harvard yard')

southerners recognize they speak with a drawl (and every souther state residents identified some other states as having the worst)

and most NYers will admit, that terti terd and terd (or is it turti turd and turd?) is not unknown in our fair city (i grew up with a friend who said turlet (tur like turtle +let for toilet.)) and that fran dresers nasal twain had a hint of reality..(not that i speak that way you understand!)

my other obsession