Ensure that you’ve selected a correct sound output device in System Preferences > Sound > Sound Effects (section) > Play sound effects through. Also ensure that your output volume is not Mute. Finally, ensure that the alert volume is set correctly.
Ensure that you’ve selected a correct sound output device in System Preferences > Sound > Sound Effects (section) > Play sound effects through. Also ensure that your output volume is not Mute. Finally, ensure that the alert volume is set correctly.