As ockham has mentioned Adobe Audition is very good I do use it for what you are wanting to do, plus other things. I have also taken my voice and changed it into my bosses voice (it took a while to do it with a lot of tweaking). I am a male and have a very deep voice and my boss is female and has a very sexy upper midrange voice. When I finished it sounded just like her. Adobe Audition is the way to go also with several VST plugins (those will help...alot)

PoserPro 2014, Windows 7, AMD FX-6300 6 core, 8 GB ram, Nvidia GeForce GTX 750 Ti