I'm running KDE on Debian Testing.
From time to time, programs running in a terminal (Konsole) trigger system notifications of the form "Bell in session Shell".
What triggers these notifications?
Note: I'm not asking how to disable them - I know there's an option to do so in Konsole -> Settings -> Configure Notifications. I'm asking what behaviour triggers them in the first place, with a view of possibly modifying some of the programs that trigger them to not trigger them, or to trigger them under different conditions.