rear end howl. sounds like a bad bearing, but it isn't

[Myles]

I'm trying to diagnose an issue that I have been dealing with for a while now. I drive an 07 Yaris which emits a loud howling noise from the left rear tire. This noise becomes noticeable around 40 mph, and gets louder as the vehicle speed increases. When I turn the wheel to the right, the noise will go away, but when I turn it to the left it becomes worse. I suspected the bearings were bad, so I put new ones in, but that did not lead to any improvements. I replaced the tires, coil springs and shocks, but still no luck. I'm now suspecting an alignment issue, but I have read that these cars can only be adjusted with shims. I have the printout from my most recent alignment which was done when the noise was still a problem. The left rear lists -1 camber and .11 toe. the right is -.8 camber and .2 for the toe. does this seem far enough out of spec that it would cause this type of problem? I'm at a loss. any help would be appreciated.