Oh, I understand. Thanks for the explanation.

Regarding noisemakers, I should rather say noise making devices, I guess. Here is a company promoting theirs (quick Google search): https://mardersicher.com/marderschreck-mardersicher-ms-12v-m... Googling for an example, I just discovered that the German Wikipedia has an extensive article (https://de.wikipedia.org/wiki/Marderabwehr) on defense mechanisms! The devices are supposed to only emit ultrasound. In practice, most don't.