Rear road noise louder with speed? Not tires!

[evo-r]

Thanks for all the responses. One weird thing is that the shop that stated it's some bearing in the differential actually put the car on the lift and put in "drive" at various speed while 2 other people were underneath the car to hear which side the noise is coming from (with mechanics stethoscope). Their conclusion were the noise is coming from the center near differential.

Based from the noise change from left & right sweeping motion, I'm just going to replace the passenger rear bearing first and go from there.