A free program for Android, by Autotune Voice Changer.

Tune Your Voice With Music is a free app that lets you change the pitch and the speed of your voice to make it sound like a variety of different characters. 

How can you use it?

It is really simple to use, and is designed for both beginners and advanced users. With it, you can record your voice and apply different sound effects to change the tone.

Add different sound effects and modify your voice to take it to the next level. Moreover, you can send the recordings to friends and family or set it as a ringtone.