Ford: 1997 Taurus front end noise

I have a 1997 Taurus and a howling noise is comming from the front
end. The noise starts at about 30mph and gets loudest at about 45mph
and up. A vibration is also felt along with the noise. The noise is
the same when accelerating, decelerating and braking and doesn't
change when turning. The auto trans fluid level is ok and fluid color
looks good. The noise doesen't seem to be comming from one side of the
car or the other. Any ideas?

Brad