not quite fair...
not really...
I see where you're coming from, but you're being a little misleading on your use of figures there, but in any case the issue is that the corresponding sounds in the room have to go up to compensate for the extra noise.
say you were at 40dBSPL with your computer fans, and playing battlefield with your speakers set to a max 75dB SPL, that'll let you hear footsteps in the game which are 35dB lower than the gunshots, say, which are the loudest sounds.
Up your fan noise by adding an industrialheatingelementcumgraphicscard, and you're at 70dBSPL noise floor, which means you can only barely hear the gunshots anymore, and the footsteps are long gone... so you keep getting knifed. In order to hear the footsteps again, you turn up your speakers by 30dB to get the footsteps above the noise floor, bringing you to gunshots 105dB SPL...
Realistic some might say, lol... but even soldiers want to wear earplugs at those kinda volumes!
Also, people don't realise how loud 85dB sustained volume actually is (that's a louder sustained volume than a lot of drumkits) - it's well above the level of hearing loss whatever H&S documents say... it's a volume you have to really shout over. If you ever go into a small studio room with a level meter, and turn up the speakers until you hit 85dB, you will find it incredibly uncomfortable. It causes 24 hour temporary hearing loss after only a minute or two, and if you work at that level regularly, you will permanently lose high frequency hearing even if it doesn't show on the crappy hearing tests which stop at 8kHz generally. The only engineers who work close to 85dB and above are those who have already lost a chunk of their hearing... most of us work lower than this most of the time - frankly, I'd do a lot of proper work at 70dBSPL, lol (though sadly as I get older I'm having to go louder... :-/ )
-Fergal
The grenade just seems appropriate...