Starting about 100 miles ago I began getting a knocking sound from my left front wheel, which was not very noticeable at first, but now is. There is one knock with each rotation of the wheel that can be felt a little bit through the steering wheel. I suspect either the wheel bearings or a CV joint. But one thing confuses me--when under heavy acceleration or while braking, the sound & feeling almost completely disappear. I would not have guessed to get that behaviour from either of the 2 problems I suspect. Any ideas? Do one of these problems usually exhibit this kind of behaviour?