Sound insulation between rooms with suspended ceiling

Hello team,

we are currently building and our drywall installer has built the interior walls with gypsum boards. He always only builds them up to the roof beam but not up to the OSB ceiling of the attic. He does it this way on all sites. The ceiling will still be suspended. Insulation is in the attic and therefore not intended between the roof beams. So, basically, there is air under the suspended ceiling. And now we are afraid that we do not have sufficient sound insulation between the rooms. What do you think?
The drywall installer said that it is too expensive and complicated to build the panels all the way up and cut them accordingly. He would line it with mineral wool. However, I do not know if that provides sound insulation. Do you have any ideas?

Mineral wool absorbs sound quite well. The gypsum board is not exactly a soundproofing miracle either. Just put in wool and that's it.

What kind of stones are these? 11.5 ones? They hardly provide any sound insulation anyway. Speaking from my own experience... I’m also with the drywall installer. Just want to get in and done. Anything more here is over the top.

These are 10 cm plaster blocks. And the wool would then simply be wedged between the beams. Otherwise nothing special, right?

The drywall installer said that it is too expensive and complicated to build the panels all the way up and cut them accordingly. He would line it with mineral wool.

I wouldn't have let them end that far down, but it seems sufficient to me and is probably also widespread. What is underneath: acoustic ceiling or closed panels?

I wouldn't have ended them quite that low, but it seems sufficient to me and is probably common like that. What's underneath: acoustic ceiling or closed panels?

I only went there after the work was finished, and the inquiry revealed that they have apparently been doing it that way for years, and the home construction company also sees no problem. Underneath are just normal panels. No acoustic ceiling. It's a single-family house and above is only the attic.