I'm not sure if my answer should even count because I'm from Canada but...
I say
Caroline like
Carol + the "ine" from "shine". It's very distinct from
Carolyn, which is like...Christmas
Carolin'. It's interesting that
Caroline is seen as more "hickish" with the people you talk to, because I'd say that it's the opposite up here.
Carolyn is more downmarket and common, while
Caroline is self-consciously sophisticated, even a snobby upper-echelon name.
Does your professor have a pronounced accent? The 'line' ending of
Caroline does offer more of an opportunity for a stereotypical southern accent to affect pronunciation I bet. Carolaahne.