If you want to do more research, "articulatory phonetics" is a good phrase to start with. "Acoustic phonetics" might help, too.

I REALLY hope the 'hiss' the writers are talking about IS a kitty hiss, because otherwise FAIL.

And I forgot!--if you want to get carried away (I'm not sure how into this you want to get), there's a few other things you could do with your vocal cords themselves. Your character could mess around with phonation and change the acoustics of the voice. It's possible that this would be a good detail if you want to use it.