2002 LS Cavalier

My cavalier sounds like a Daytona car going down the road. (it hums) You can feel a little vibration in the floor. I have visually inspected the exhaust and it does not appear to have any holes. To double check this I put the car in neutral while rolling down the road and revved the car and the noise did not change. Could it be some bearing or bushing going on the cv joint or maybe in the transmission? I have 60000 miles. It is a 2002 2 door coupe, ls. The tires are new with about 8000 miles on them. The control arm bushings were replaced last year. It is not the same noise it made when those were bad. The sound gets louder the faster you go, so it's got to be something to do with the rolling motion. Any guesses, before I take it to the garage? Thanks!