Are you hearing that noise from the top of the rear windshield or from trunk area. If it is from the trunk compartment then there is a TSB for it regarding using expansion foam to fill the gaps between metal panels. If the noise is coming from the top of the rear windshield, between the glass & roof area. Then it could be the clips on the glass that was used during assembly at the factory. These clips will have to be removed in order to eliminate the noise and that requires removal of the rear windshield and resealing.
Good luck with yours.
Good luck with yours.