Brick filled or unfilled, relevant for interior sound insulation?

Cheaper and similar setting as well as shrinkage behavior.

I don’t understand now. If the brick is narrower, there is simply less air inside, right, or am I misunderstanding bulk density?

The higher the density, the higher the sound insulation per cm of wall thickness.

10dB more attenuation results in halving the sound. The scale is logarithmic and not linear.

The higher the density, the higher the sound insulation per cm of wall thickness.

Sure, but if I now take 11.5 cm wall thickness times 1.4 density value, I get the value "16.1" (crazy calculation, I know...). If I take 17.5 times 0.8 density value, I get the value "14" -> then the thinner wall would be better in sound insulation?? Does anyone know how to calculate this correctly?

Further insight from the technical data sheets: An increase in bulk density allows for a significant improvement - I did not know until now that in the brick designation the bulk density is given immediately after the thickness and that bricks with different bulk densities can be purchased with the same thickness:
Poroton-Hochlochziegel-Plan-T 11.5-0.8 -> 41.6 dB
Poroton-Hochlochziegel-Plan-T 11.5-1.2 -> 45.6 dB
Poroton-Hochlochziegel-Plan-T 11.5-1.4 -> 47.5 dB

Poroton-Hochlochziegel-Plan-T 17.5-0.8 -> 46 dB
Poroton-Hochlochziegel-Plan-T 17.5-1.4 EB -> 52.3 dB [EB probably means earthquake, indicating that it is suitable for all earthquake zones.]
Poroton-Hochlochziegel-Plan-T 24.0-0.8 -> 49.6 dB
Poroton-Hochlochziegel-Plan-T 24.0-1.4 EB -> 56.1 dB

Conclusion: The value 0.6 in the bulk density class x 10 corresponds approximately to the improvement of the dB value (=6), so it is almost proportional.

Sound insulation aerated concrete has 63db at 24 raw density 2, thus almost twice as much attenuation as the best brick.

That is interesting. Can you be a bit more specific about what it is and which manufacturers there are? Google search yields nothing useful... What does it cost per stone? What are the U-values?