If you're talking home defense, then no matter what caliber you carry, it's going to be that pop of the first round be it 380, 9mm, 38 Spc, 357, or 40 from which to protect your ears. Wear your sound reducing hearing aids 16/7. Saving your life is more important than "what if". I doubt a one off is going to eliminate your hearing. I am willing to bet my hearing on it.
My hearing is down by 50% in both ears since childhood I think. Blowing up rolls of caps on the concrete curb under Dad's 16 oz. Carpenter's hammer. We didn't know! Box after box after box. Too late when we found out.