hso, I also said that this seems to be good for only a shot or two, and I also said that it seems to apply while hunting, I never said this would protect you in military situations, which in my experience usually last longer than a couple of rounds. I also mentioned from my experience how even that won't protect you from unusually loud firearms, and that even hearing protection won't necessarily provide complete protection either.
I am pretty certain, as Dentite also mentioned, that the ear has some limited built in protection, and I am pretty sure I read about that in an American Rifleman article a long time ago (although I might have the actual description of how it works wrong), but I never meant to imply that this would save your hearing in any way during military service. And it certainly won't help you for the high duration noise that one is often exposed to in daily service.