Absolutely, and really quite naturally. I've been involved in public speaking since elementary school, so vocal modulation comes easily. Whenever I'm dressed I just start speaking as Vivian would, without thinking about it.
The daughter of a colleague grew up in Georgia with a thick southern accent. She was accepted to college in the state of Washington. She tried hard to eliminate the accent for fear of being taken as a hick. One week after school starts my colleague talks to her daughter on the phone, and the southern accent is back with a vengeance. It seems the daughter discovered that the northern boys all love the southern accent!