I was just in a VRC world chilling with someone talking about random bs - when all of a sudden, both my speakers from my Valve Index shot out this deafeningly loud BZZZZT sound for about 1 second. 
It scared the everliving fuck out of me and I jumped - then about 5 minutes later it happened again. So I got off. 
What the fuck was this??? I was lying down with my cable resting behind my head, also the headset is about 3 months old. I've never experienced this before.