How can I change the recorded voices into fun voices in iPhone?

I have seen some iPhone apps in whi开发者_C百科ch recorded voices are made into fun voices. Is it possible to programmatically change recorded voices into fun voices using an iOS library?

I found some app like Voices 2 ~ fun voice changing!, Talking Tom etc. How do they do it?

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It looks like OpenAL could give you what you want, and there are other options: See here and here, here, and here.

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Talking Tom uses Dirac I think: http://dirac.dspdimension.com. They have a free LE version as well (should be sufficient for voice processing).