I got to talk to one of NIOSH's engineers a couple of years ago, and spent quite a bit of time asking him some very basic questions, and picked up a lot of good information.
One of the things you also have to consider, is the shock wave which travels through the stock of a rifle or shotgun. Most folks think that it's just the noise. A rifle or shotgun stock besides transmitting a shock wave, also displaces all hearing muffs, no matter what the quality (dependent on whether you shoot right- or left-handed). And, if you have a beard, it can also break the seal. The other problem is shooting glasses. They all break the seal, so you can never be assured that you're getting anywhere near the protection that muffs offer.
I've worn a combination of custom molded ear plugs, and very high quality electronic muffs (Peltor Tactical Pro and Pro Ears Gold Magnum) for years, but I'm headed to the ENT on Thursday for tests. I know I have some hearing loss, and it's especially noticeable in my right ear (right-hand shooter).
I just wanted to update this thread with the results of my visit to an ENT on Thursday, 8/7/14:
The intake medical assistant asked the usual questions relating to general medical health, etc. She also wanted to know in which ear I believed the hearing loss was worst. She made a lot of notes, and then sent me for a hearing test with the doctor's audiologist. She conductive a complete hearing exam, and then discussed her findings with me. My hearing is exactly the same in both ears, and my hearing loss has been determined to be completely age-related. That's the bad news.
I next saw the ENT. He also discussed in detail my hearing test results. He also advised me that my loss was completely aged related. The audiology report was completely within those norms. He advised that I could gain some benefit from hearing aids, and he provided a referral which I can take anywhere, should I decide to get hearing aids. With the amount of loss I have, I've opted to wait for a year, having another hearing test, so a baseline can be developed.
The doctor is a shooter. His chosen shooting sports are clays and skeet. He's also a handgun shooter. (We did spend some time discussing the pros and cons of Glocks v. S&W M&P, and he was surprised about the Colt Super .38 which I carry.
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I asked him about the possibility of hearing loss from using a shotgun and rifle, through the stock. He advised that while it is a possibility, there is far more concern by not wearing appropriate hearing protection. He understands the lack of complete protection because of hearing muff displacement. So my initial fear about more hearing loss in my right ear was put to rest.
I brought my custom molded ear plugs and my electronic ear muffs (Walker Pro Ears Gold Magnum), and he advised me to keep wearing both. That this combination was as good as you could get. He was impressed with the quality of the custom plugs, and I gave him the audiologist's card, in case he wanted some like it. He also mentioned that two years was about the maximum before having new plugs molded.
Just from my experience, do not wait to have your hearing checked. The ENT and the audiologist really make a good team.