Skype/Teamspeak voice changer Free program?

Hey! Im workin' on a project to we see the internet fakes and belive, i want to make a test of this kind, and i need a voice changer... Preferable teamspeak or both of tham. SKype is great to!Please help me for get a free program of this! Thx a lot for now! I'd like a Female voice like 15 years old if some1 know the settings maybe to pleaze print-screen and link it here. It would be realy helpfull!