Why does Half-Life start replaying my audio from about five minutes ago

Roughly 5 minutes into playing Half-Life it begins playing the audio from 5 minutes ago and its really loud and I can't hear what's actually happening in the game. It continues playing even after quitting out of the game (It's happening while I write this). The issue has only just started happening today and has happened even after I restarted my computer. Any help would be great.