To clarify, the effect I'm referring to occurs when your guardian is very low health and close to death. At this time the in-game sound effects become muffled and echo-y, and you can hear your guardians' heartbeat. This effect generally dissipates when your character regains health or dies I've experience an issue where this audio effect does not go away. This issue arose when I quit a mission as I was about to die. I loaded up a new mission and the audio was still sounding like I was near death, minus the heartbeat. I loaded up a patrol mission after that and the effect remained. I reset the game and that corrected the problem. Not a serious bug by any means just reporting it here in case someone cares.