I’ve just found a fascinating article by Lisa  Theriot on accents, that  also pokes a little fun at “the curse of Dick Van Dyke” if you’ll recall his performance  in the film “Mary Poppins”.

Find it here

While you’re at it, there’s a very good book by Robert Blumenfeld called,  Accents: A Manual for Actors.
Plus it comes with a very handy CD. The man has an amazing command of just about every accent on earth, including regional dialects.  Very helpful for creating characters in audio book , character, and other voice acting work.

I just copied the image- The “look inside” doesn’t work if you click the image. 
But if you’re so inclined click  a peek, do it here: Look Inside