Could be a wheel bearing, but they tend to growl, and get worse with time. I'd check the tires carefully. Put a rear tire on the front, do one side, then the other, and drive it in between to see if the noise changes or goes away, i.e. try to isolate which tire might be making the noise. You can also jack one side up and spin the front tire, you'd be surprised at how easy it is to see if its out of round. Also, a belt could be or have delaminated. My thought is to rule out the tires before you start spending money on parts. The sealed wheel bearings seem to be reliable. Good luck.