I don’t know if this is really a problem with Plasma or what it really is. But after installing Manjaro on my old HP ProBook 450 G0, I have this annoying error sound, which sound like a very old-fashion static kind of sound, every time I e.g. get no results in a search in a web page in Firefox, or I press key combinations that don’t exist, such as ~ followed by - or ` followed by p etc.
I haven’t found any place in the system settings for this, and the worst thing is it doesn’t even go off when I disable the speakers. That is, the screen looks like on the picture, but I still get these error sounds.