When I was in New York, I met a wonderful voice/dialect/movement coach. Andrea Caban. You can contact her at: firstname.lastname@example.org.
To European actors I thought she would be most helpful as a dialect coach and she actually coaches on Skype. So you don't have to go to New York to get her services.
She is also a wonderful actress. See her work at: http://www.andreacaban.com/Welcome.html