Attached ceiling panels made of Styrofoam

By the way, I would definitely want to "improve the acoustics" of reinforced concrete ceilings.

That's exactly what they are for. That is not a disadvantage.

Many thanks to everyone for the information, tips, and opinions. We are still considering, but will definitely decide soon :)

Stretch ceiling as an alternative. Meanwhile with various materials and design options. Should be inexpensive and quick to install. The dismantling as well.

That's exactly what they're for. That's not a disadvantage.

I meant the room acoustics (hard ceiling, reflections, unpleasant during conversations...), not impact sound etc. ;-)

I meant the room acoustics (hard ceiling, reflections, unpleasant during conversations...), not impact noise, etc. ;-)

I also meant the acoustics. The panels are soft and not smooth. That is good for the acoustics.

So, regarding these Styrofoam ceiling tiles - I understand what you mean. They really seem like the easier option compared to filling, sanding, wallpapering, and painting.