Suppress
You can suppress a suppressable messages that you find superfluous by clicking on its name in the list.

Suppressed messages are not ticked and not highlighted. You can  enable a suppressed message  by clicking its name in the list shown to the right.

Sound
Click and hold on the header of a  message with sound symbol will change from enabled to disabled sound and vice versa. You are notified when your action has been registered (unless you have not suppressd the notification).