It is time to service my car. I complained about the car is getting noisier when driving. The serviceman called me in the afternoon to inform me that the front wheel bearings have been replaced. I have no idea what that is. But after I picked up my car, the noise has been reduced significantly. It used to make a constant noise when turning right. The noise is now gone. It may be the same reason described here. The car seems to be a lot quieter even when driving.
If this is really the root cause of the problem, why didn't they change the bearings the last time I complained ?