Let's kill this Robert Mason shit with a quick Google search of "Robert Mason Ozzy".
4th result from the top of the search- Ozzy backup vocalist from 95-96.
I'm sure there's some processing going on with Ozzy's vocals at the soundboard, but they sure do let a lot of cracks and lyrical flubs slip by if the "effects" are as heavy as some people think they are. Honestly, I think they probably just give him some standard EQ, reverb, a pinch of autotune and echo when the songs call for it. Anything more than that, and it would be legitimately noticeable.