Very effective, if done correctly. For a truly well isolated room we must use two layers of studs and completely fill the empty scape between the studs with mineral wool. It is smart to use gypsum plates of differing mass/ thickness. It is very important that the wall is constructed from the floor (bearing structure) to the ceiling’s bearing structure. It is also important that the metal studs are mounted onto a few millimetres thick tape made of foam (PET).