2002 Oldsmobile Aurora CV shaft

If this noise was there shortly after the wheel bearings were replaced, it is likely due to improper installation procedures. Some people set the vehicle on the ground with the wheel installed to hold the axle shaft from spinning when they tighten the nut. At that point the new bearing has already been damaged and will be noisy. There must never be any weight on the bearing when the axle nut is not torqued to specs.

That brings up the second cause of a noisy wheel bearing. That's to not torque it properly with a click-type torque wrench. Almost all front wheel bearings call for at least 180 foot-pounds of torque, which is a real lot, but most GM front-wheel-drive cars call for 240 foot-pounds.

This assumes the noise you're hearing sounds like an airplane engine.

Did you read what I wrote about improper installation procedures?

Were both bearings replaced? If not, how was it determined which one was noisy?

Dandy. The next suspect would probably be a rubbing splash shield behind one of the rotors. I've also run into a few axle shaft seals that make a squeaking noise but those were on Chrysler products. The way to find that is to spray any type of light lubricant into the opening of the transmission where the inner cv joint goes in. You have to douse it pretty good to get enough to run all the way in there. If it's a noisy seal, that oil will quiet it down for up to a day, but that's it. The only permanent fix is to replace the seal.

There is a tool you might be able to borrow or rent from an auto parts store that borrows them called the "Chassis Ear". It is a set of six microphones, a switch box, and headphones. You clip the microphones to suspect points, then drive around while listening with the headphones. You can move the microphones around to zero in on the source of the noise. Be aware that many mechanics have never seen or even heard of this tool. Suspension and alignment mechanics use it to find rattles, squeaks, and other noises.