Hmmm, I always notice when a singer is singing in a different language and they're trying to focus on pronunciation, their voices tend to change. Even the way it sounds, not just its strength, begins to change. You can see this when BoA sings in Korean, Chinese, Japanese, and English... And I notice it in SNSD too.. and for WG, I noticed it as well. Voices seem to get deeper for Asian singers who are trying to sing English... Maybe that has something to do with it.
-O_sLaVe