Alternative 1
The grille can be connected to the ductwork using a plenum, with mineral wool as sound attenuation material.
Alternative 2
The grille can be connected to the ductwork using a balancing plenum, which comprises sound attenuation material of polyester fibre with a washable surface or mineral wool. The plenum has an airflow measurement and adjustment unit. The grille is removable, in order to provide access to the measurement and adjustment module in the plenum.