Most commonly experienced when an explosion sets off near a player, hearing impairment can be simulated in a couple of ways. It is sometimes depicted by merely turning down the sound in game, as if the sound effects have been drastically lowered or muted.
More commonly, however, it is associated with the ringing sound a person would hear experiencing a loud sound. This phenomenon—called tinnitus—occurs when extremely loud sounds cause the stereocilia in your ears to continue vibrating even after the sound wave has passed. Games often simulate this when grenade is tossed and explodes near the player. It is sometimes accompanied by a visual impairment that simulates the disoriented feeling associated with a loud sound and flash of light.