Robovox is pretty fun to use for quick and dirty sound experiments to add to songs and of all the voice changing apps this is the only one that I found satisfying...
Google Play info:
- Android 6 Marshmallow ready
- 8 new voice models added
- 10 voice models for free now
- Improved button layout for realtime, parrot, recording and play mode
- Recording time extended to 5 minutes