Sound insulation - differences in interior doors?

can also be done via the upper frame ventilation.

Of course, but even then you can do without chipboard, because the "noise" finds its way through the frame.

Is it really that critical with the ventilation system? The room is not hermetically sealed for the rest of its life...

Does anyone of you know the Planet minE-S system? It is an overflow channel in which the air can circulate and air equalization can take place. To ensure that the sound is also insulated, the lower door gap is sealed tightly. I recently came across the system on the Internet.

I have to pass on that. I only know that sound always takes the path of least resistance (if you want to put it that way).

As our architect said... what good is the 1800s KS wall and the top insulated window if the sound (in our case airplane noise) mainly comes through the roller shutter box and the opening for the range hood?

I have now also measured again... the gaps under the door are 0.4 to 0.6 mm... so that can't be the reason, can it?

You probably mean cm, right?

That’s not much, but quite a bit for sound.