Well, er, he wasn’t doing it in that final drugged-out phone call he made the night he died, or whatever that was. I won’t link to it, it’s really disturbing 
but it was even deeper than his arena-crowd voice. It barely sounds like the same guy, and not childlike at all.
I think there is some footage of MJ sounding like a “normal person” as he talked to his dancers during rehearsal in that documentary @nungesser mentioned, but I didn’t see any convenient clips from it on Youtube when I was looking for examples.
