Sounds like a possible bearing failure, can you describe in more detail what your doing when you hear the noise and what makes it go away if at all. In my experience bearings can be noisy w/o doing anything at all. Or you hear it during braking and usually while turning which typically identifies the outside bearing as the failed one. Any other odd things like vibration or pulsation while braking?

LIFT OR BUST! 2001 Sportage EX 4dr 4WD with 300,210 miles & counting .....
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