ᐅ Sound insulation between brick walls/concrete lintel and wooden beam ceiling

Hello,

Our wooden beam ceiling was apparently installed not directly on the concrete ring beam of the masonry walls, but on wooden supports, possibly due to low ceiling heights on the upper floor. This has resulted in a gap of about 5cm (2 inches) between the walls and the ceiling. The ceiling will still be covered with drywall, but I am concerned that this gap may create a significant sound bridge between the rooms.

Now my question:
What can I use to soundproof this gap?
I have thought about the following options:
- Mineral wool (ISOVER acoustic)
- Foaming the cavity (are there specific soundproofing foams? I assume they should be open-cell?)

What would you recommend in this situation? Filling the wall cavities with bricks or similar is practically impossible due to the already installed battens, etc.

I look forward to helpful advice.

Regards
mertmk3

Please try sketching the situation.
I don’t see any point in filling the gap since the ceiling is not solid anyway.

Nevertheless, the ceiling is well soundproofed, right?

Here is a picture showing the wooden beam ceiling with a vapor retarder on top, battens on the left, and the wall between the rooms at the bottom. You can almost see through it. On the 30mm (1.2 inch) battens, there will be an additional 12.5mm (0.5 inch) drywall. The gap to the wall can just about be closed. However, between the rooms there will be only two layers of 12.5mm (0.5 inch) drywall.

I wouldn’t use foam; I believe specialized sound insulation wool could be an option.

Oh, so there is insulation and a covering inside/on there? Well, just fill it with mineral wool.

Yes, there is 240mm (9.5 inches) insulation in the ceiling.

Which mineral wool would you recommend?