This is what the app will do:

User speaks into the phone, the app will then change the voice in a few different ways and play it back.  The app will also store either the original or processed voice into the filesystem.  I don't need very extensive processing, something simple like changing the pitch of the voice is good enough.

Check out the Voices app on iTunes: http://itunes.apple.com/us/app/voices-fun-voice-morphing/id337447139?mt=8