As voice coach to the International Professional Program at CNN, I was exposed to countless dialects on a regular basis. I think performers often mistake an accent as something that relates only to sound and attempt to “study” that accent by listening to audio tapes. An accent is part of a person, their physical being, culture, upbringing, class, etc. In developing accents for theater and film I strongly recommend “going to the source”, in other words, finding a REAL person from a particular region and observing the way they speak, gesture, shape the sound and physicalize language. If that fails I recommend watching films with actors from a particular region. Some video rentals have sections devoted to “films from other countries” with actors speaking English with their native accents.