I am looking for an algorithm that will allow me to adjust pitch of a sound sample (specifically human voice). I have tried shifting a spectrum, which i obtained through FFT, but that introduced much noise. (it is also rather slow since I need to do a complex transfom as oposd to a real, but time is no object although real time is kind of great...)
I have also tried FIR and IIR algorithms, but they did not preserve tempo of the source.
If anyone knows how to implement a pitch shifter, please email me.
Thank you very much,