Meh I'm not so hot at this. Unless they have a distinct voice or I come in contact with them regularly chances are good I won't remember.
I usually resort to playing detective if someone comes up and just starts talking. Normally they will hint to a past conversation or family member or something that will clue me in to who they are.
I guess I could just ask but this way is more fun.

I'm going to go with yes, I had someone ask me this the other day because he said hi to me as I passed him and then later apologized for not identifying himself (something people rarely do for me anyways) and asked if I still knew it was him. I did, it's not like I have better hearing, but I think I pay more attention to it than my sighted peers. It doesn't work every time though, so while I can make pretty good guesses that are often times accurate when I can't ID people with the vision I do have I mostly opt to just say hey back if I'm just passing them to save embarrassment of calling them the wrong name on accident.

I think so. But it isn't because we have any sharpened hearing or anything, it's just because recognizing voices is a skill we practice out of necessity. Also, I'm just answering on a hunch; I'm not aware of any studies or data to back me up, and I do know some sighted people who are better at recognizing voice actors and actresses (in cartoons and video games) than I am. But I still feel like I'm better at recognizing voices in real life.