2002 Jeep Liberty: Increased road noise at 25-35MPH

I'm the sole owner of a 2002 Jeep Liberty Limited that has 49,000 miles on it. For the past two years a problem with noise has gotten worse. At low speeds, roughly below 25 mph I don't hear much additional noise, other then the engine and tires. But as I speed up to about 35 mph, the noise increases. The noise sounds is low pitched noise, and sounds like a bad case of tires and road condition but it gets so loud that it's difficult to talk without shouting. The noise starts to disipate at 40-45 until it isn't quite so noticible at 55+.

I don't believe it is bearings as there is little to no noise at lower speeds and I've had bears go on me 4 times on other vehicles, and the noise isn't quite so rough, but close.

The noise raising pitch between 35-50 mph. I've replaced the tires, did a 4-wheel alignment ( not for this purpose but.). There is no change in noise if the Jeep is put into neutral when driving. Engine load doesn't appear to make any impact. Braking and acceralation don't make any impact.

I'm wondering if this could have been something that has been bad all along. This jeep was my wifes and it never was all that quite. The ball joints were replaced ( by factory recall ). Could something have been damaged by them?

Thanks in advance.