Choose or disable the alert sound
Your computer will play a simple alert sound for certain types of messages and events. You can choose different sound clips for alerts, set the alert volume independently of your system volume, or disable alert sounds entirely.
Open the Activities overview and start typing Sound.
Click on Sound to open the panel.
In the Alert Sound section, select an alert sound. Each sound will play when you click on it so you can hear how it sounds.
Use the volume slider for System Sounds in the Volume Levels section to set the volume of the alert sound. Click the speaker button at the end of the slider to mute or unmute the alert sound. This will not affect the volume of your music, movies, or other sound files.