According to this page, which is written for 19.04, I'm supposed to disable alert sounds by switching the alert volume to off. However, if I go to Settings > Sound, I only see the following:
I see no Alert Volume setting. Any other way to disable the alert sounds?
To disable alert sounds on Ubuntu 19.04 you could install dconf editor, either from terminal or from activities/software center. From terminal
sudo apt install dconf-editor
Next, launch dconf editor and navigate to org/gnome/desktop/sound/event-sounds and flip the switch to off - alternatively, click on event-sounds and set custom value to False
From terminal without installing dconf editor
gsettings set org.gnome.desktop.sound event-sounds false
