You may have to have your wheel bearings inspected, when they have failed they can give off a whining noise. Have a professional take a look to verify that this is what your concern, as to not have any further damage.
A whining noise coming from the back of any vehicle is not a good noise. I recommend you take it to your regular auto technician for a diagnosis of the noise. Can not tell you anything from just a description.
〉 Answered on Aug 20th, 2013 by Amy Mattinat, Owner and Author at Auto Craftsmen Ltd
Have your rear differential checked.
〉 Answered on Aug 20th, 2013 by Barb Petrey, President - DBK Enterprises Inc at Jiffy Lube