@ujcmtgs4n4jqza I used thick cork panels, some foam material and also I packed everything in the closet very very tight, adding a lot of clothes and stuff, so now I got more free space in other rooms and I have done test with recording devices around the house, sound stays mostly in.

Thanks, I am actually thinking of starting to share stuff... even if I'm not good, just as an excuse to practice and get better.
It's one of the advantages of not knowing anyone in person here!