Brick filled or unfilled, relevant for interior sound insulation?

Here as a supplement to my above question, some "hard facts" from the technical data sheets: Poroton-Hochlochziegel-Plan-T 11.5-1.4: 47.5 dB (evaluated direct sound insulation value Rw), density class 1.4 Poroton-Hochlochziegel-Plan-T 24.0-0.8: 49 dB (evaluated direct sound insulation value Rw), density class 0.65 Poroton-T8-24.0-MW (mineral wool): 46.3 dB (evaluated direct sound insulation value Rw), density class 0.65 [Perlite in 24er not available at all!]

-> I believe these max. 2.7 dB hardly play a role in everyday life.

However, I wonder: Why is the sound insulation better without mineral wool?

And: Why is the thinner 11 cm brick "denser" in terms of density class?

Cheaper and similar set as well as shrinkage behavior.

With the interior walls we have I can only say not so many problems, however I would never take just 11.5 that is way too thin... we have one between the guest WC and kitchen and the difference to the others that have 17.5 is literally massive.

also be careful: toilet flush or shower thermostat should not simply border e.g. the children's room otherwise you can hear the flushing. That doesn't have to be.

however, I would never take only 11.5, that's way too thin ... we have one between the guest bathroom and kitchen and the difference to the others that have 17.5 is literally massive.

I would probably rather take only 10 cm, as a gypsum board.

That is a naive calculation. 11.5 density 2 has better sound insulation than ytong 24 density 1.

Therefore, you cannot compare apples with pears.

however, I would never take only 11.5, that is way too thin … we have one between the guest WC and the kitchen and the difference to the others that have 17.5 is literally massive.

As an addition:
Poroton-Hochlochziegel-Plan-T-17,5-0,8: 46 dB (weighted direct sound insulation measure Rw), raw density class 0.8
-> That would be 1.5 dB better sound insulation - can that make such a big difference?