I'm glad I ran into this chat. Am familiar with Walker Game Ear, Peltor and Caldwell and foam plugs. Ratings from 23 to 31 decibel noise reduction. Have approached university professors of audiology/speech science on having them or students help me with research on sound levels of various black powder rifles, pistols, shotguns, muskets, fowlers, revolvers and even a cannon with parade loads and live rounds. Only published data I could find to date used a TC in line Encore with 250 grain projectile and 150 grains pyrodex. About 159 decibels. You should not expose yourself to noises over 85 decibles for much time without protection. Loud noises over 140 decibels without protection will damage your hearing. That is why I think a study needs to be done with traditional black powder firearms. Staff at a near by university thinks that they can help me out.
The Peltor did go through more batteries and the padded ear cover fell apart after a while. You can hear someone whisper 50 yards away and hear range commands. When hunting you can hear a deer or elk walking in the forest. However when the wind blows loud enough it suppresses sound just like when a shot goes off. Most all the muffs interfere with good cheek weld but I use both foam ear plugs and muffs if using a modern rifle with a muzzle brake. For normal range and club shoots the foam plugs work just fine with most black powder rifles. Proximity to other shooters on the firing line is a factor - closer being more a risk of damage.
You can spend a lot of money ($1,500.00) on fancy electronic plugs that are rechargeable and have blue tooth capability. Last thing I need when hunting or shooting for score in a match is a phone call. Some companies have moldable plugs that you either heat in hot water or use a two part epoxy that sets up in 10 or 15 seconds. I've seen them priced at $40 to over $150.00. I don't have time or money to test them all but would do so if I got free samples from a company and wrote a review for a magazine that pays its writers a decent commission. Manufacturers sending you free samples expect a favorable review.
Protection is not additive - that is a pair of foam plugs with 25 decibel suppression under a set of muffs rated at 25 decibel reduction does not give you a 50 decibel total reduction. Poor fit over glasses, beards, hats, caps, etc. can reduce effectiveness of hearing protection devices. Sound is also transmitted through the bones in your skull. I personally have never had a failure on the range with my electronic muffs quitting or amplifying the loudness of gunfire. Keep batteries fresh and carry spares. Not obeying range commands because you can't hear them makes you a liability to everyone on the line. Can be embarrassingly if not just plain dangerous.
Sound level meters from Home Depot for $350.00 are not sensitive enough to monitor anything above 130 decibels. They can measure 120 decibel noise of circular and chain saw, gas powered leaf blowers, rock concert loudspeakers and other industrial noise. A particular sound level meter at the local university starts at $4,500.00 and then you need to buy calibrators and smaller microphones. The peak noise impulse only lasts about 10 milli seconds. The more I get into the research the more I realized it was not something I would be able to do without help from the experts.
A good point made in reading some of the research is that spectators of shooting and sporting events that are near gunfire without hearing protection are risking damage to their hearing. For some reason the noise going into the left ear of a right hand shooter is more intense. A shorter barrel's muzzle blast like on a pistol or carbine is more intense than a longer barreled rifle of similar caliber or load because the muzzle is closer to the shooter's ear. Tightly patched round balls have higher pressures than smoothbores with round balls held with wadding on top.
If anyone in this forum has literature or research on hearing damage due to shooting black powder firearms, please let me know. The leading cause of hearing loss is something called presbycosis. (sp?). It is age related hearing loss. So if you are older and been shooting a lot you can expect your hearing to suffer even if you wear hearing protection. I can guarantee your hearing will be damaged if you don't wear protection. Loss of high frequency hearing goes first. A friend with 5 tours of duty in Afghanistan came home with tinnitus and noticeable hearing loss. There is a lawsuit pending on defective ear plugs issued to our troops. Another friend with cochlear implants still doesn't hear clearly. Hearing aids can amplify sounds but not restore the high frequency hearing. Once you lose the cilia in your ear your deafness is not really reversible. Protect what you have left.