Be careful here. I had the same sound for the past several weeks on an
Oldsmobile. Had already changed the front bearing/hub assemblies, and was
convinced that this was one of the rears.
Instead, it was diagnosed as cupped and damaged tires as a result of bad
struts. As soon as he said it, my head just dropped, because every GM I
have ever owned has absolutely eaten either shocks or struts. Apparently,
nothing has changed with them.
I suggest you take the car to some kind of mechanic and have him rotate (and
maybe re-balance) the tires. While that is being done, have them spin the
wheels with the car in the air, inspect the tires, and run a general
inspection on the entire car. Firestone Complete Auto Care will run a
thorough inspection along with this for just the cost of the rotation, which
is nothing if you get your tires through them.
That should identify your problem. I'd hate to have you spend money on
items that really don't need replaced.
And BTW, you don't have to have bad struts for one or more of your tires to
start making that kind of noise. A separated belt, cupping, any number of
things will make your tires do that.
Hope this helps.