Having earplugs in the game as an item would be a feature that caters to realism, and I am totally in favor of this solution when concerning the real risk of damaging hearing from exposure to digital audio streams.
Many young people, being chronic headphone users, are now experiencing deafness at alarming rates, because of prolonged exposure to unsafe decibal levels.
If earplugs are not added, perhaps there are other immersion friendly solutions to this issue.
If it were possible to adjust the volume of specific sound effects, I can imagine many would mute a selection entirely, including vehicles and probably gunshots, (I understand how this could be looked at as an unfair advantage in DayZ, if it were like this from the start would anyone complain?). I know I am not alone in this, but I play with no audio. That isn't to say that high quality sound effects aren't important, it's still a neat thing to have and helps avoid hearing damage,(more variation in pitch because of higher quality = less strain on specific cochliae in the "ear drum".) Higher pitch sounds will do more damage than lower pitch sounds, it has to do with cochliae length.
It's important to remember that DayZ is a game, and playing it shouldn't sacrifice the players real health, even for a gimick. Repetitive keystrokes - (not mentioned here), and loud audio - (the topic of this post), are some topics that should be investigated to help users inclined to live healthier, exist healthier.
I'm interested in seeing a proposition for this issue; an in game item of earplugs would suffice, let players spawn with a meager pair in their pocket.
You could have an over the neck variant:
It has a slot in the inventory
Pressing a keybind toggles earplug activation
Don't animate, just make two static poses for them, one in the ears, one around the neck.
If it clips, it's fine, address that issue when you address clothes clipping.
You could also have a pair that takes up one slot that can be found in hunting lodges:
When players put them in, give earplugs two memory slots.
Toggling these earplugs swaps them between memory slots.
If there is no earplugs in the earplug slot, then nothing happens.