You say it is louder with the radio ON? Is the sound actually coming through the speakers at all?
A defective brake hose can also cause a caliper to bind up.If the caliper is not releasing completely on one side the brake pad could be dragging creating a groan or boing sound as it fully releases. Some of the Hyundai cars have a brake caliper that has sliding parts and a slight rust build up can cause the caliper to hang up and not release properly when coming off of braking as when you are starting to getting going again. If it happens only when turning left it could be a caliper on the left. If it is happening when turning right it could be a caliper on the right hand side of the car.
If it is none of these things maybe you have a gremlin or a mischievous spirit living in your car's machinery.