Pretty much what the title says. A gunshot is among the loudest noises an average person will ever encounter. Repeatedly doing this without hearing protection causes permanent hearing loss in the real world. Given that EFT focuses on firearm realism, I believe this mechanic would be a fantastic boost to the unique immersion found in Tarkov.
Update: u/jbed24 and u/hhunkk recommended lowering the volume instead of a ringing noise (perhaps cutting it to 10% volume). I feel this would be a fair compromise between realism and user experience. We would just need to ensure the effect applies to flashbangs and other stun items for consistency.
Update 2: It’s actually concerning how many users here have mentioned that playing Tarkov has caused them actual hearing damage and real-life tinnitus.