darenager is spot on with his advise.

You can’t basstrap that room, you would need at least half the space for that to work.

I want to add that the ideal weight/density for broadband panels is about 55kg per cubic meter, rockwool sells multiple kinds of mineral wool with that weight(Rockwool 221).
Don’t use mineral wool that’s heavier than that unless specifically made for acoustics. You can use lighter but then it will need to be thicker.
Make it at least 10-15cm thick.

Your room is about 30cm higher than the average room, so you could use that extra height for some more damping material.

If you use curtains, try to find the completely light-blocking kind.
The heavier the better. Or layer light ones with the heavy cotton stuff.

Also, never use reflection filters on mics.
They are a horrible solution in almost every situation.
Treat the room or place the mic in a better position.

2 Likes