woo woo noise from rear end/wheels/u-joints?

My 94 TA 6-speed has a very odd noise coming from the rear of the car. I cant tell if its the u-joints, wheel bearings or the diff. It gets louder as you accellerate and I can take it out of gear and the noise is still present. It sound does change when I turn the wheel.

I have a 97 firebird. When i bought it i was aware that it had a bad right rear wheel bearing. However when i got the prob checked out i not only had a worn out wheel bearing, but also bent right rear axel which caused the bearing to go out. im almost positive that you have a worn out wheel bearing, mine was making the same noise especially when going around curves.

what kindof noise is it? is it a high-pitched squeel, or a thunking noise, or a grinding kindof noise?

Its not a grinding or thunking and it is more of a low pitch whiring kind of noise like a siren almost. The noise seems to be consistent with the wheel speed. I am fixing to change the diff oil and will be pulling the axles and replacing the bearings. I was just hoping someone has had the same experience so that I stop worrying about the diff being bad. Thanks.