Muffled game sound

Usually the first game after I’ve turned my xbox on the sound is fine, then afterwards most of the games the sound is muffled. It’s not crisp at all and when I sprint you can hear your spartan making strange grunting noises. It’s really annoying as its rendering my 7.1 surround sound headset useless because you can’t hear people walking around behind you.
I’m using a one x and razer thresher ultimate headphones.

Any help with this and I will build a statue out of muffins in your honour