I wouldn’t know how the sound is supposed to pass through the frames, which stand about half a centimeter away from the wall? It’s not a continuous hole, but a kind of mini-labyrinth – according to reports on the internet, this is supposed to be negligible in terms of sound permeability.
That’s how we installed it as well – the controlled residential ventilation seems to work. We can’t hear the washing machine, nor the dryer.
Much more important upstairs – with the door closed, we don’t hear our loudly screaming son. However, there are three doors in between – still, that was very remarkable. Overall, we are extremely satisfied with the sound performance… not even all the doors have been adjusted so far.
Everywhere, building lime sand brick was used and Ringo doors with tubular chipboard core were installed.