1
Open the Messages app on your Mac.
2
In the top menu, click on Messages and then select Preferences (or Settings).
4
Uncheck the box that says "Play sound for incoming messages."
1
Click on the Apple menu () in the top-left corner.
2
Select System Preferences (or System Settings).
3
Click on Notifications.
4
Find Messages in the list and adjust the alert style or turn off sounds.