To help with room acoustics it’s typical to get absorption at the primary reflection points and, for bass, in the corners and to some degree diffusion but in smaller rooms absorption tends to be a bigger issue. The trick is getting the right amount of absorption without killing the space. These products tend to incorporate rockwool and fiberglass of varying densities with denser products absorbing lower frequencies. Foam panels are often used but just aren’t as effective as rockwool and fiberglass as thin foam only tends to absorb the higher frequencies.
Now if you are looking to reduce sound escaping into your neighbors condo that’s a different treatment. There you want mass, multi layers of gypsum board (drywall) or better yet chase walls built with an air space, then wood studs with batt insulation then multi layers of gypsum board. Better yet again, concrete block. Eliminating sound from entering another space is much more difficult than acoustically treating the listening space itself. Bass and the long wavelengths associated with those signals are the enemy for sound control.
Now if you are looking to reduce sound escaping into your neighbors condo that’s a different treatment. There you want mass, multi layers of gypsum board (drywall) or better yet chase walls built with an air space, then wood studs with batt insulation then multi layers of gypsum board. Better yet again, concrete block. Eliminating sound from entering another space is much more difficult than acoustically treating the listening space itself. Bass and the long wavelengths associated with those signals are the enemy for sound control.