Hyundai Repair: 2002 Santa Fe 2.7 AWD automatic (Noise), wheel bearings, all terrain tires


Question
My Santa Fe has 122000 KM on it and so far not so many problems.
Since a few weeks I noticed that the car got very noisy when I drive around 80 -130 km/h. It seems that the noise is coming somewhere from the front but not the engine and it's a sound like if u have some very rough all terrain tires on the car but of course I haven't.
It sound like the wheel bearings were bad so I replaced them, but the same noice is still there and it's really getting anoying. It's almost hard to have a normal coversation with that noise.
This is my first car with an automatic. Could it be the transmission or the transfer case that makes the noise? But when I put the car in Neutral while I hear the noise and let it roll I can hear the same noise -not less and not more-  so it doesn't go away when the car is rolling in neutral.
I change the transmission oil every 40000km


Answer
There are several possibilities.  First, feel your tires.  If you have significant flat spots on the tire tread, the noise is probably coming from the tires.  

If not, it could be coming from the transfer case.  If you determine it's not the tires, I'd recommend taking to a shop for diagnosis.  The shop will be able to operate the vehicle on the lift and listen for the source of the noise while the car is on the lift.