Well, as to the wheel bearings, I imagine the sound would seem to be coming from more outside the car. This seems to come from the inside center, or from the front...the engine.
I've actually had the heat shield issue already, so it's not that. My mechanic solved that one by removing the outer, offending, heat shield.
So, the buzz is more engine compartment than anything else.
I'm still stumped. The transmission, maybe?
