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 Sounds section, click on Alert Sound.
Select an alert sound. Each sound will play when you click on it so you can hear how it sounds.
To change the volume of the alert sound, return to the Sounds section, click Volume Levels and adjust the System Sounds slider. Click the speaker button next to the slider to mute or unmute the alert sound. This will not affect the volume of your music, movies, or other sound files.