Pitch correction using fourier transform!

Hello everyone, I'm kind of new here and firsttimer using matlab, but i've got an assignment for my university. It's sort of a proyect for voice processing, and i decided to do an autotune algorithm, pitch correction using the FFT, i've been messing around with the program, and i've managed to record my voice using recordblocking and using x= getaudiodata of the recording object i could apply the FFT to x ... to get the signal in the frequency domain, my idea was to somehow alter the values of the frequencies in the signal and then using the inverse fourier transform i would see the effects on the sound like higher pitch for higher freq values, but i'm kinda stuck on how to modify or even show these frequency values, and any information would be greatly appreciated, how could one modify the fundamental frequency of a given signal?

Answer 1

[Paulo Silva]

Autotune toy

[Ricardo]

I've been using that as a structure example, but since he's code is mixed with matlab's autogenerated onef or the user interface it's hard to keep up with what he did or he's using, and i honestly don't understand much, that's why i'm asking for more input here, but thanks for the suggestion!