Of course, the authors being from Germany, they may have different expectations about how the existing noise environment colors people's concern about a little more/less noise in general.

I remember taking subways (subways!, not even to mention HSR) in Germany (Munich, Berlin, etc) where you could hear a pin drop during the journey, and where you could talk to your fellow traveler in a whisper.

Go to New York or Boston, and people look at you like you're a wimp if you ask why the train is screeching so loudly.

And then another example, if you've lived in the UK for any time, you come to believe that cars are supposed to make the constant diesel-level cranking noise even at idle. And then you go across the channel and find that miraculously, cars can actually be manufactured to be quiet.