Woo, Woo, Woo sound 35 - 45 mph

Returned from FL (1200 miles) 3 weeks ago. Car has always been flawless. Two days later get into the car to run our son to PHL. Around 35 - 45 mph I get the woo, woo, woo sound like a wheel bearing our tire. Above 50 mph I can't hear it any more. Sound does not change with load, (acceleration, coasting, decceleration). I convinced myself that it was tires since they were worn down to the wear bars. I just got the car back from the State required safety and emissions inspection and new tires and nothing has changed. Same sound, same speeds. I can only hear it in the car. Cannot hear it outside with the window down. I cannot feel any vibration. Above 50 mph it is silent.
Has anyone experience something like this before? Any suggestions on where to start looking?
Thanks, Bob C



