Thx. I've not done anything on the rear. not checked the oil and actually did not know the wheels even had bearings .
When I open the window to listen, I cant hear the noise, so it may be something underneath, like you say. I switched the fronts and will know tomorrow if that changes anything.
The tires are a year old and my DIY alignment is a little older. I started noticing the noise a month or two ago, I think.

https://photos.google.com/photo/AF1Q...jywg_blOw1HlaI

Edit: switching tires changed nothing.
The sound I'm hearing is similar to blowing over the top of be a coke bottle, repeatedly.