The first thing to do is plug any holes between the two rooms if they exist, after that it gets increasingly difficult/expensive. Ideally you want a floating false wall sealed around floor, ceiling and side walls, with a lot of mass and/or limp membranes included.
The first thing to do is plug any holes between the two rooms if they exist, after that it gets increasingly difficult/expensive. Ideally you want a floating false wall sealed around floor, ceiling and side walls, with a lot of mass and/or limp membranes included.