4046 as PLL and a CD4059 as programmable divider
This PLL was first published in March 1983 in Free Radio Magazine and was re-published a year later in the same magazine. It uses the well known 4046 as PLL and a CD4059 as programmable divider.
I'm betting it's been done, might be underwhelming..
The hardware version looks cool, you feed it MIDI note data and it tries to morph the input to reflect those notes. I suspect software is kludgier for real time use, but also probably a lot "better" in execution in that it's not ~ 20 years old.
I'm flirting with GAS over here, need to shore up my gear budget I suppose.
EDIT
So, this fucking thing has been bugging me enough that I pulled a manual in hopes that I'd get a deeper understanding of what's going on.
According to the manual, pitch correction starts the process (which differs from harmonizing or intelligent pitch shifting) by tracking the frequency of the input. So, with a non-periodic signal like white noise, it appears the processing engine will reject the signal. From what I can tell, the quiescent "rejection" mode of pitch correction is simply untreated bypass. So instead of the exaggerated clusterfuck of what one would expect from a harmonizing pitch shifter (which, to my knowledge, is just full pass manipulating time base of a signal) the intonation correction would simply revert to bypass to be as unobtrusive as possible.
Sort of analogous to the blue screen versus static screen in the realm of analog video.
So, my GAS has relaxed quite a bit, though it could be nifty on feedback or drone material it sounds like a nuance machine that is not quite better than my hundred bucks.
I put some noise through Melodyne a bunch of years ago, it was fun for a bit of a while, making all the sounds one note, or turning it into Springsteen's "Philadelphia."