There is a feature called smart notifications for agents within the portal itself which would give real-time audible notifications about new tickets and updates on the ones you are working on. You can open the Notification Center by clicking on the bell icon from the navigation bar next to search. 

You could choose the ones you want to get these alerts for by clicking on the desktop icon in the notification center. You could enable desktop notifications in this window.

Muting is possible by turning on the "silent notifications" within the Preferences tab. 

For detailed information please refer to this article.