Loud intermittent whining from front end

Hi, I am desperately seeking advice as to how to stop the annoying whining coming from somewhere in the right front part. It is not a belt because it never happens when parked and does not depend on RPM's. It is unpredictable, sometimes starts almost immediately after you start driving, while sometimes it seems okay, you drive it on a highway and then you slow down and suddenly the loud whine kicks in and does not stop until you stop. This is not from brakes, they are done, and it does not change at all when you brake or turn. I already replaced the wheel hub but no result. I strongly suspect the right axle support bearing or even the transmission output bearing. How can I find out for sure?