Audible Logic and Acknowledging Alarms

The Notification Center shows indicates whether or not active alarms have been acknowledged (viewed).

Unacknowledged alarms are displayed with red text in the Notification Center.
Acknowledged alarms are displayed with black text in the Notification Center.

When a new Notification is displayed, the audible tone is played untill acknowledged

Acknowledging a Notification, either by pressing a pop-up notification in the bottom right hand corner; or by pressing a notification in the Notification Center, silences the audible tone for all Notifications, but only acknowledges the selected Notification.
If multiple unacknowledged Alarms/Notifications are present within the same team, acknowledging one of them, acknowledges all of them (within that team).