From my bedroom out to the living room is a long hallway; a shot fired in there would resonate in a bad way, I'd imagine. Multiple shots and it could be disorienting. Being shielded from that would provide an advantage, I would think, especially in the situation if multiple shots were fired. Obviously, the likelihood of ANY of this happening is very low, but that doesn't keep many of us from being prepared in the first place. Keeping my elecmuffs out and ready is no biggee for me. Whether I choose to take the time to put them on or not would obviously depend on the situation.
For those concerned about the 'extra time', consider this -- is it not possible that you'd "hear something" suspicious and begin your hunkering down process? Wouldn't that also assume there was a time gap between that first sound you hear and someone actually being a threat to you? Obviously, if someone busts open the door to the room you are in and that is the first warning to you that something bad is happening, well, just be happy if you can get your gun out. It was my understanding that the safest thing to do in the case were you are nearly certain you are under siege is to play defense... i.e. don't seek out the danger, wait for it to come to you (if at all), and be ready to respond.
FWIW, I have not ever heard a shot without protection, so am not sure of how loud and/or disorienting it would really be.