Soundproofing old wooden beam ceiling

Here is a construction principle with heavy construction boards and several insulation layers

Viewed from top to bottom:
floating dry screed board (25 kg/m2) with wood fiber insulation board
gypsum fiber board (32 mm / 48 kg/m2)
beam cavity full insulation
decoupled, freely suspended and cavity-insulated suspended ceiling with Silentboard panel (17.5 kg/m2)

Actually, a decoupled, freely suspended and cavity-insulated suspended ceiling with Silentboard panel (17.5 kg/m2) should be sufficient for your construction. Would you have enough room height for that?

Here is a construction principle with heavy building boards and several layers of insulation From top to bottom: floating dry screed (25 kg/m2) with wood fiber insulation board gypsum fiberboard (32 mm / 48 kg/m2) beam cavity full insulation decoupled and cavity-insulated suspended ceiling with Silentboard panel (17.5 kg/m2)

Thanks, the beam cavity full insulation as loose fill? Could become a problem with the weight. Unfortunately, the decoupled suspended ceiling cannot be implemented, I had already thought about that too.

The decoupled suspended ceilings are actually really good when it comes to sound insulation. As mentioned, you can find a lot on the internet with concrete examples of which measures have which effect. In the end, we only installed dry screed, which honestly brought almost no benefit. In any case, I would combine several measures according to the circumstances.