How do I turn on Calendar rings but turn off notification rings

Hi! I have a Nexus 5. I need to keep notification sounds off (gmail, facebook messenger, etc.) but I need calendar event alarms to stay on and make a loud noise that wakes me up. I tried downloading the Calendar Event Reminder app, but it only rings if notification ring is turned on, but I can't turn on notification ring (I am in class a lot). Is there any way that I can get calendar events to make a ring, but all other notifications to stay silent?