It might not be a total surprise – Us germans don’t generally do well in directly settling matters. It is a matter of politeness, you can’t just go and tell your neighbor to turn off his damned stereo. He’s not supposed to ever have it too loud and so it would be inpolite to point out that it, in fact is, too loud.
Of course it doesn’t get better after a while you simply wish him to die in a fire.
the soundtrack in today’s case would have been Flesh Field’s Strain:
Turn the balance to this speaker only, tremble to minimum, bass to max, loudness to max, and then it will be tolerably silent in your own room but the bass will crawl through the walls. If neccessary, deploy second speaker and put your laundry on the speaker to eliminate resonance.
I guess only japanese are that complicated.