
In general, women have those resonances (all the harmonics and stuff) higher than men, which sounds like an increase in pitch. Theres a lot of videos on youtube that can go in to incredible depths, but basically your vocal cords make a tone, and the shape of your mouth and nose makes a wacky resonance that when moved quickly in the right way sounds like words.

A voice's perceived gender is actually way more complicated than just pitch.
