Of the guns I shoot the most, my 18” barrel 5.56 is OMG loud. It has a very effective muzzle brake/suppressor mount that works well for reducing muzzle rise; but it trades lack of muzzle rise for a giant increase in noise. My competition pistol and 12 gauge are pretty standard in their ability to turn money into noise. My other primary noise offender is my F-class rifle. The 30” barrel helps to get the noise away from my ear, but 50-ish grains of powder is still quite loud.
For all of these centerfire activities, I use a double layer system for protecting my hearing. The first layer is a set of foam earplugs, then muffs.
The ear plugs I use are 3M Skull screws, the decibel rating is 32db. They are all I normally use for protection when shooting rimfire or suppressed. Having the foam plugs inside the ear does two things. First it reduces the overall impact of the sound entering the ear canal. Second, by physically filling the ear canal it also reduces the secondary vibrations that travel up the jawbone by acting as a dampening device. This is especially useful with rifles as the cheek weld is a direct transmitter of these secondary threats. Any fairly firm foam plug would work, but a higher “db” rating is better and the ones I use don’t slowly work their way out as you shoot.
My second layer of protection is a set of active sound deadening earmuffs with ambient sound amplification technology, the Dillon HP-1. These muffs add another 21db of sound rating. They also have the ability to cut out all sound over 85 db a few microseconds after it hits. The best part is they can amplify sounds lower than 85 db on a rheostat.
Muffs of this style have a passive rating of between 18-24db. In the manner I use hearing protection, the passive rating is not as important. The primary passive sound reduction comes from the foam plugs. The muffs work more on concussion reduction in the passive role. In the active role, the muffs crop out sounds over 85 db and can amplify desired sounds. This could be the sound of quarry animals while hunting or commands at the range. This belt and suspenders combination makes it possible to easily keep aware while target shooting or hunting, yet not risk hearing damage.
It should be noted that 32db plugs and 21db muffs do not add up to 53db of sound reduction. Being a logarithmic scale, it doesn’t work that way. Each 3db is doubling of sound intensity, even if the ear does not perceive it that way. The combo I use likely gives a maximum of 41-44db of direct reduction; but it also helps in the other ways mentioned.