Axle seals can squeal but only when the car is moving. You normally won't hear them at highway speeds. Front wheel bearings will sound like an airplane engine.
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.
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Wednesday, October 17th, 2012 AT 8:19 PM