Air flow path through CLS W219 interior

[Phil1968]

I'm looking to put sound deadening on the underside of the parcel shelf (to block a small amount of drone from the exhaust, which seems to emanate from the boot area) as it seems to be quite thin & not too well insulated for noise. The rest of the boot area seems quite well sound insulated. There is a fine-meshed grille on the top part of the parcel shelf that runs almost it's entire length & 4 medium sized holes underneath, it's difficult to ascertain whether they communicate with the grille, I'm hoping it's not part of the air extraction path for the interior as I don't want to block them off when I fit sound insulation to the underside. I can't see where the cabin air extracts to the outside.