Prefabricated house, poor sound insulation

Just for understanding. You have a house within the 5-year warranty period and you think it is too noise-permeable. Instead of having an expert report made, which could also reveal the reasons and allow you to have the construction company carry out repairs, you just want to have all the window panes replaced yourself? And if that doesn't help, you continue with the wall?

Has anyone here really ever done this? Called in an acoustician? Is that even the right term? I only find hearing aids on Google. What exactly does he do, what does it cost? Does he really measure what resonates there and how? Where we are, they only wanted 800 euros to measure whether it is loud, and that is useless because I can measure that just as well with my phone...

Someone like a certified expert for construction defects. Because it has nothing to do with acoustics, but whether the house was built according to recognized rules of technology. If not, there is a claim for (free) rectification.

Yes, always get an expert first before thinking for yourself .... that's how they make good money.
The OP would surely not just replace the pane if he assumed he had a defect!

You seem to know a lot of people. And if he rightly replaces the windows, then it was indeed a defect! Otherwise, money thrown away. It's obviously easy to speculate from a distance when it's not your own money.