dubcac is correct, i kno. my driver's side wheel bearing needs replacing and it sounds more like a constant rubbing sound. imagine a wobbling rim or a flat tire, like a constant "whomp whomp whomp" sound... it's been a year now that i have been driving this way im just too lazy to pull off the knuckle and have the bearing replaced. but yeh back to the point, its your axle cuz i have the same problem too.