Is there any particular American dialect that does this? I have heard this kind of pronunciation on some American TV shows, mostly featuring teenage/college kids, and it appears more prevalent among female speakers. Often, the girls who feature such pronunciation also exhibit qualities of Valleyspeak in their speech and I am wondering if they are related.
Am I hearing things or is it actually an identifiable and well-known pronunciation habit? Is there any established pattern that associates it with any particular dialect?