I shot .308 competitively for my battalion, without hearing protection. Today I am mostly deaf in my left ear (left-handed). A buddy forgot to put his plugs in (I fault his guides) when firing at a mulie in a box canyon - think he used a 7MM Rem Mag or 300 H&H Mag - 20 years later he still has tinnitus and has to put cotton in his ears when he is in a noisy crowded room.
When people ask me for my personal opinion about in-home defense, I recommend against .32 Magnum, .357 Magnum and .44 Magnum (and their cousins) because of the sharpness, volume and high pitch of the report. I'm not a scientist and haven't yet read all the replies in the thread, but the reason I like .45s is the lower-hertz report, if that's what it is called. Velocity presumably plays a large part in all this, but that's for the scientists or engineers to discuss. Obviously, when it is hitting the fan you shoot what you have and you almost certainly won't be wearing plugs, but planning for a real event should be able to mitigate hearing damage to some degree.
At indoor ranges in particular, I never remove my ear muffs unless I visibly confirm that every other lane is cold. Otherwise, I just shout and or mouth or signal what I want to say to whomever is with me. An option, probably already mentioned, is expensive electronic earmuffs that "shut down" when the report of a cartridge hits them but that allow normal voice-level sounds through otherwise. The cost is relative. Good hearing aids begin at $1,500 each. High-end "expensive" electronic muffs are waaay cheaper than that.
If you want to be an eternal optimist, losing your hearing means you can't hear very much nagging, either.