For a project I'm currently working on I would like to change the prosody * of a given voice sample. In other words, I need to pitch shift a voice sound without altering the formant frequencies that make up the characteristics of the voice. It's not a requirement for the system to run real-time.
Does anybody know any C or C++ (or actually, any other language) library which could achieve this?
* Prosody is the pitch of a (human) voice.