Kill, tower, dragon, and inhib announcements not working.

Whenever anything that is supposed to get an announcement happens the pop up that shows what happened just flashes on screen and disappears quickly without the announcer saying anything. ex. "You have slain an enemy!" normally the picture of my champ, my name, the enemy name and their champ appear. It still comes up but only for a millisecond and the announcer doesn't say anything. The voice for the announcer is turned all the way up in my sound settings so I don't really know why this is happening. Please Help!