F 150 Supercrew 2001 humming noise at stop

I have a Ford 2001 F 150 Supercrew, 127,000 miles, 4.6L engine. No major probs., serviced regularly per manual. Did get new tranny 50,000 miles when blew out but no probs. since. Noticed humming noise coming from right front, seemed like worse when accelerating, but not consistant. re-did wheel bearings, and now still notice but \now also happened when fully stopped at red lights, began the low pitch hum about 1 full minute, then stopped.

Any clues to what this is?