low pitch noise

My 98 Grand Prix SE has a low pitch noise coming from the front end when i hit 30+mph. I was told the left front wheel hub was bad so i replaced it. and it is still making the noise i was wondering if it could be the other hub or somthing else.

Many times hubs go out at the same time. You replace the noisiest one only to find out the other is growling too. Just to be safe, check the tires as well. Run your hand along the tread both forward and backward. If the tread feels as though it has sharp points as you run your hands along it (especially in the opposite direction of rotation), your noise may be the tires.