I grew up in a small rural town in the US. While some farmers claimed that the daily noontime test was a handy call to lunch that one could hear over the roar of the farm equipment (especially since most farmers kept their wristwatches nice for Sunday ... just like a neighbor kid who lost his arm in a corn auger had a hook for work and a latex "Sunday hand" that screwed on complete with bike derailleur cable actuators), the real reason was a holdover from WWII air raid siren tests.
I'm not sure if Germany ever had those as well. I attended an event yesterday where someone was moaning about how the
churchbells bothered him, so I'd doubt it.
During the
duck and cover era, we were all taught that if the siren went off and just kept wailing and wailing, it was the Big One. Therefore, whenever the siren began to wind down again, I always was flood with a sense of relief that non-noontime sirens were "only" a fire or ambulance call.