A half inch thick layer of bonded recycled fiber sound absorption material will be glued to the inside of the panel in areas where it will not interfere with the door or window mechanisms. I sourced this material from an upholstery shop where it is used for similar applications. It is easy to cut, conforms to the curved surfaces, and bonds easily with spray adhesive. Also, next time the carpet around the trans tunnel is accessible, a layer of this material will be added there as well. gordo