MorphVOX

MorphVOX allows you to change your voice when playing online games, making phone calls and other activities where you use a microphone.
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> You can choose between different characters such as female or child voice. The app can also handle fictional characters so you can speak as Dark Emperor, Commander Gordon, Droid and more. The program works seamlessly with your microphone and automatically converts your voice to the one you choose when you launch the app.
> Most of the voices sound realistic by default, but you can still tweak some of them to your taste.
You also have the option to insert sound effects to liven up your conversation.