I get this question a lot, so I figured I would take a stab at actually explaining it.

For Hello, I recorded 3 vocal layers all through the built-in mic on my MacBook. Two of which were in my normal speaking pitch, and one an octave up.
I put a noise gate on all three channels and a spreader on each of the lower octave takes. The stereo spreaders allow you position the track in the spectrum which work great in conjunction with the pans. I let one channel lean to the left so you could better hear there were a few of me in there.

I wanted to make this sound mostly human so I went easy on the pitch-correction (auto-tune) and only applied it to the falsetto track. To make the falsetto track step from note to note I set the response speed to fast. Since I was recording this while sitting on my couch with a beer in my hands, I turned off the D#, F# and G#, where my voice accidentally slid to a few times. It’s actually these little mistakes that let the pitch-corrector work it’s magic, so to speak. When the response time is turned all the way up these “mistakes” force the corrector to jitter between allowed notes, struggling to avoid the notes that have been turned off. You can use this method to get those Lil’ Wayne vocals that must cost him so much. I detuned the track a bit too, just to give it a bit of harmonic tension since all my notes were now proper accurate. Fuck accuracy.

Now for the fun part. I have each of the 3 vocal layers each routed to 3 separate channels, the main out for each track all routes to Bus 13. Bus 2, 3, and 6 all have some form of delay effects to compression to EQ and a stereo spread before hitting the master. I’m not going to get too into revealing my trade secrets here, but the idea is to set up a few bus channels with different types of effects on each and then route those bus channels to different bus channels. Most of the bus channels that I set up resolve at bus 13.
Bus 13 runs everything through a standard Logic compressor and a lightly driven tape emulator (PSP Mix Saturator - Part of the PSP Mix Pack). It runs through a few more of Logic’s standard dynamics processors, some more EQ and then out to the master.