Well, my normal voice is "sort of deep" and I can push it lower, if need be. And I'm assuming by 'boy' and 'girl,' you mean 'male' and 'female,' right? ^^; I'm not exactly young (21), so my voice doesn't sound very boyish.
However, I don't have anything in the realm of voice recording software, other than the standard one windows comes with. If you know of one that's free or has a short trial, I have no issues downloading.
Let me know.
Kularian