1998 LS 4X4 Rear Wheel noises

It seems that I have a squealing/humming coming from the rear of my vehicle.
When I'm driving I will only hear it when the windows are down. If I am going straight I will only hear it sometimes, not all of the time. When I am turning left I usually hear it on the left side of the vehicle and vice versa on the right side, though it can be the other way around, turning left and hearing it on the right hand side.

I'm guessing it's a wheel bearing or rear axle bearing. Is there a way to diagnose the problem and do it at home? My knowledge of vehicles intermediate at best. If not, what would be a rough estimate on repairs at a shop? I dislike going to the shop due to getting parts at wholesale prices, however I don't want to do anything that could cause any permanent damage.

Thanks for the help!

Make sure it is in the rear.

What speed?
Does it increase with MPH?
Have you checked rear pads and emg brake shoe?

Rear end noise checking.
http://www.differentials.com/install.html


Jack it up and put it on stands and see if you can hear it with rear wheel turning.
http://www.differentials.com/install.html

It's usually at lower speeds that I notice it, on the highway it may be drown out by road noise but it is not very pronounced. In MPH I'd say it is most prevalent between 5 - 40MPH, after that road noise takes over.

The brakes were just done so I am somewhat certain that that is not the problem.

I jacked up the vehicle today and there was a bit of play in both rear wheels so I am planning on starting with the bearings this week once the weather clears.