Walt Wolfram debunks this myth in a number of ways. He states that it doesn’t matter where one lives, whether in an anglo-american community or in sorrounding neighborhoods once black, this myth will always exist. He further states that some people justify this myth with the fact that it might be due to differences in lip size, which is funny but untrue.
I agree with his views and that the english language has a vast variety of dialects. Verbal speech is like art, and all the differences just adds to its beauty and richness.