my 1999 Buick LeSabre makes a loud noise when backing up , this has just started , please help , something is not right

 

If rear disc brakes, could be a stone lodged in-between rotor and pad. Sounds like a wiped out wheel bearing.

 

Is it possible for you to have someone either drive the car or get close enough to listen for where the noise appears to be originating ? Left rear, right rear. ?

Could involve brake system parts. Helps if the area can be determined to save time and trouble of removing and checking everything.