Ironically, when I write and not worry about a particular character's "voice" it just sort of springs up unannounced. When I try to force the issue I usually end up with a character who sounds like a smug sarcastic know-it-all, and that's my voice!
My main characters are smarter, funnier and more principled than I am, but they're also products of their era, which is more-or-less now--so their use of idiom, etc., probably isn't that far from mine. So, when the engine of Coffin's dodge bursts into flames in my #1 he says "Motherfucking fuckball!" Pretty close to what I'd say in that situation, I imagine, though one never knows for sure until it happens.
What great answers! I hope my characters have a voice of their own but realize that they are me if I was them...sort of. If I were a person with that attitude, point of view and background, then that is how I think I'd act and speak...Maybe. Also I may have unconsciously known someone somewhere that resembled this character in behavior or thought process. I know I don't act as my characters do, but to a degree they do have my voice.
I like writing as both male characters and female characters, so I guess I get to exercise my masculine side and hope my "guys" aren't too feminine. Since I'm a little bit dainty, a little bit tomboy that isn't a problem so far.
Writing does give one a chance to explore all sides of things and to project ourselves into another entity whether it be the opposite sex, various religions, or even an inanimate object. Maybe it makes us understand better and become more tolerant for others problems.