Brick filled or unfilled, relevant for interior sound insulation?

Soundproofing pumice has 63db at 24 raw density 2, so almost twice as much damping as the best brick.

I live in a pumice multi-family house and can't complain.

Can you be a bit more specific about what that is and which manufacturers there are?

Look in the pumice area with the usual suspects: KLB (climate lightweight block), Riffer Bisotherm, Meurin, Ehl, ...

if I now take 11.5 cm wall thickness times 1.4 raw density value, I get the value "16.1 (crazy calculation, I know...).

I couldn't have said it better :-)

Please definitely remind the TE to also include the windows. Our brick has 43 dB, unfortunately the windows only 32 dB. Unfortunately, we didn't pay attention to that. I've already had the bedroom window panes replaced, now the floor-to-ceiling windows in the living and dining room are next. It annoys me. But since the neighbor announced child number 5 today and his sloping driveway (I’m just saying Bobbycar) runs right along the boundary, I have to bite the bullet otherwise my nerves will break.