Like a jet eh? Well it could be the tires, and if they are the original tires that came with the car, that means they are like 7-8 years old and should be replaced anyway. But I doubt they are making much noise, that's usually more common with high performance wider tires.

But the sound you are describing could be a wheel bearing. The noise increases as speed increases, is independant of motor speed. From my experience with other cars, if you are on a somewhat curvy road, as you go around bends, it'll get louder when you load up that side, and quieter when you load up the other side, ie, it'll be louder if the bad bearing is on the right side and you are turning left, etc. Does your car do that?