doubling up, ear plugs+muffs

[testosterone]

Does doubling up plugs+muffs have a literal additive effect in noise reduction?

Like, if I put in 12db plugs and put on 20db muffs, is the actual reduction 30db, assuming perfect seals etc...?

I'm shooting several K a month, 12 gauge(trap) and pistol(.45 indoors).

When I double up, it is definitely quieter(expected duh) but specifically is the effect literally additive.

Anyone else double up? I notice ringing in my ears, not constant, it turns on and off, sometimes spiking then attenuating down. It's very obvious if I am sitting in a quiet room.

Chalk that up to being around heavy equipment as a child, thousands of hours operating power equipment, and working in loud machine and auto shops through my teens and early twenties with zero hearing protection.

I wish I knew then...

 

[rgwalt]

Yes, doubling up with hearing protection is more effective. I don't know that the effect is literally additive though. I work in a refinery around a lot of really noisy equipment. There are areas where double hearing protection is required due to the noise level. OSHA and other organizations have studied the effects of loud noise on hearing loss. You might be able to find some of their research out there.

 

[TonyDedo]

There's not a 100% transfer in protection (12db + 20db ≠ 32db) but as you've noticed, it does provide additional protection. I've started doubling up when I find myself in a noisy indoor range. However, if your muffs are only rated to 20db, I'd suggest buying a better pair.

Case in point, last night I was shooting .45 indoors next to a girl shooting 9mm so close to my head, I could feel the percussion waves hitting me. On the far side of her was four Yeah Dudes with an AR and a couple .45s. Definitely a night to double bag it.

 

[testosterone]

Thanks guys.

Tony,

I currently use a set of Peltor muffs that are 32db rated. Indoors I wear them + throwaway 29db ear plugs and the NR is tremendous.

Sometimes I double up on the trap field, but it is so effective it makes communicating on the line a little hard.

Doubling up like this got me to overcome reflexive blinking when shooting(pointer from brian enos forums on overcoming flinch).

My wife bought me a pair of electronic Peltor's that are only rated at 20db for xmas which is what got me thinking. The electronic muffs may be set to home defense only, but I'm going to give them a try at trap this weekend.

I definitely subscribe to the more is better philosophy on this subject, but I wonder what the minimum protection is to ensure no hearing damage.

T

 

[Blues Brother]

well, I use double ear protection when I use my leaf blower. those are SUPER loud and they are right on your back not far from your ears. So I grab a pair of disposables and use ear muffs as well. it works great. You can certainly hear the difference if you take one of them off. anything I do thats excessively noisy for long periods of time like that I will use double ear protection. I am a musician too, and when I play in situations that are loud I will use a pair of disposable ear plugs to cut the excessive noise. the strange part to me is that the earplugs dont hamper the music as much as you thing. I can still hear pitch effectively, they just cut out the excessive noise from drums or loud amps. I just had a hearing test last week and my hearing was excellent. so I know all the things I do to help protect it is working.

 

[RobMoore]

Doubling up does not give you the sum of the two individual NRR numbers, but there are benefits.

Apart from offering greater protection, plugs added to muffs ensures that you are still protected if your hardshells slip off your ears for some reason.

Doubling up works almost too well. Somtimes you can't hear anything, so I use electronic muffs over foamies so cancel out some of that.

 

[Boris Barowski]

doubling up works, but it's not the sum of both.

I combine plugs and earmuffs to study in silence too

 

[LiquidTension]

I combine plugs with my electronic muffs if I'm shooting under cover. Out in the open I usually just use muffs. The electronics are nice when doubling up, you can still hear stuff.

 

[Ed Harris]

OSHA [1983] has instructed its compliance officers to derate the manufactuer's NRR by 50% in enforcing the engineering control provision of the OSHA noise standard. However, NIOSH concurs with the professional organizations cited above and recommends using subject fit data based on ANSI S12.6-1997 [ANSI 1997] to estimate hearing protector noise attenuation. If subject fit data are not available, NIOSH recommends derating hearing protectors by a factor that corresponds to the available real-world data. Specifically, NIOSH recommends that the labeled NRRs be derated as follows:

Earmuffs - Subtract 25% from the manufacturer's labeled NRR
Formable earplugs - Subtract 50% from the manufacturer's labeled NRR
All other earplugs - Subtract 70% from the manufacturers labeled NRR

For example, measure noise exposure levels in dBC or dBA with a sound level meter or noise dosimeter.

When the noise exposure level in dBC is known, the effective A-weighted noise level (ENL) is: ENL = dBC - derated NRR

When the noise exposure level in dBA is known, the effective A-weighted noise level is:
ENL = dBA - (derated NRR -7)

To summarize, the best hearing protection for any worker is the removal of hazardous noise from the workplace. Until that happens, the best hearing protector for a worker is the one he or she will wear willingly and consistently. The following factors are extremely important determinants of worker acceptance of hearing protectors and the likelihood that workers will wear them consistently:

Convenience and availability
Belief that the device can be worn correctly
Belief that the device will prevent hearing loss
Belief that the device will not impair a workers ability to hear important sounds
Comfort
Adequate noise reduction
Ease of fit
Compatibility with other personal protective equipment

More infohttp://www.nonoise.org/hearing/criteria/criteria.htm

 

[Blues Brother]

and another thing to remember is noise levels (decibel ratings) increase exponentially not in a linear fashion. so 100 dec is way louder than 85 decibels.

 

[FuzzyBunny]

Muffs also have the effect of covering the bones outside your ear that can transmit noise to the bones in your was. I always double up.

Silencers should be required by law with every firearm purchase.

 

[MattTheHat]

As others have said the sound attenuation is not the combined dB rating of the two devices. In my limited experience, I'd guess it would be closer to adding 3 dB to the attenuation rating of the better device. IOW, a pair of earmuffs rated at 27 dB and a pair of plugs rated at, say 12 dB really only yield approximately 30 dB of protection.

Considering an extra 3 dB of protection cuts the sound level in half, it makes a substantial difference.


-Matt

 

[Texas Gun Person]

I use both when shooting .50 Cal. It definitely helps with the noise they put out.

 

[MattTheHat]

and another thing to remember is noise levels (decibel ratings) increase exponentially not in a linear fashion. so 100 dec is way louder than 85 decibels.

Absolutely correct. 100 dB is FIVE times (5x) louder than 85 dB.


-Matt

 

[hokeyplyr48]

I'd gladly purchase a silencer with my firearm if it weren't prohibited by NY state.

 

[Dokkalfar]

dB rating is a logarithmic graph, so you can add them, you just have to do some math first

Im not sure exactly how it works (too early for me) but instead of it being 12+20, You would have something like (10^12) + (10^20).
This SITE HERE gives you a total dB of 20.6, though I don't know if adding them is the same as adding dB reduction. Sound is really weird. But given a 3dB change is a doubling/cutting in half change, that could be about right.

 

[divemedic]

I remember years ago, I took a hearing protection class for my employer. They showed the effects of wearing a pair of 23db plugs, and 23db muffs. The combined reduction was 29db.

 

[chuwee81]

i always double up as well. As a musician (amateur or whatnot) good hearing is something i'd like to keep as long as possible.

 

[Guns and more]

Doubling up will further reduce sound pressure levels, but it's not linear.
Every 3 db. is a doubling of the sound level.

 

[pikid89]

I combine plugs with my electronic muffs if I'm shooting under cover. Out in the open I usually just use muffs. The electronics are nice when doubling up, you can still hear stuff.

Me too

I use the Ryobi Audio Plus muffs, 25db

At the public state range i go to, all the FWC officers working there wear them

 

[MachIVshooter]

I use both when shooting .50 Cal. It definitely helps with the noise they put out.

Same here.

Common sense approach. Use as much protection as is required. If the noise is still uncomfortable with one layer of protection, add another.

By the same token, I don't find .22 LR fired from a rifle to be offensive to my ears, and so don't bother with ear protection when going for varmints/small game, where the number of rounds fired don't justify the impediment to hearing the critters.

 

[NMGonzo]

Quieter, and warmer in winter.

 

[Deanimator]

It's more effective, but for me, usually not necessary. The only time where I've found it to be NECESSARY was on the VERY small NASA Lewis rifle range, which was in a deep valley. When somebody shot a .300 Win Mag down there, it was BRUTAL.

 

[Manco]

dB rating is a logarithmic graph, so you can add them, you just have to do some math first

Sure you can add them, which then translates to multiplying their corresponding linear values. For example:

log(1000) = 3
log(10000) = 4
log(1000*10000) = 7
log(1000*10000) = log(1000) + log(10000) = 3 + 4 = 7

See?

Im not sure exactly how it works (too early for me) but instead of it being 12+20, You would have something like (10^12) + (10^20).

That's only if you wanted to add/subtract the linear values. Hearing protection devices don't subtract a certain amount of noise, they effectively multiply it by a certain fraction, which is the same as subtracting a number in logarithmic form--a "29 dB" earmuff basically subtracts 29 dB from environmental noise (not quite that simple in reality, but that's how the math is supposed to work).

This SITE HERE gives you a total dB of 20.6, though I don't know if adding them is the same as adding dB reduction. Sound is really weird. But given a 3dB change is a doubling/cutting in half change, that could be about right.

Theoretically, at the most simplistic level, you should be able to add the noise reduction values, but one of the main problems--among others--is that for each device measured against a human head there is some noise that cannot be reduced, and this is largely because a certain amount of noise is transmitted directly through your skull to your inner ear. For example, true 20 dB earmuffs and true 20 dB foam plugs cannot reduce noise by 40 dB when used together, even though the math would suggest it, because the same noise that leaked in before is going to leak in now regardless (in fact, it might not be physically possible to reduce noise this much without completely enclosing one's head). That's only part of the limitation (I'm no expert on hearing protection), but it's just to give you some idea of how things work.

 

[ChronoCube]

+1 for Manco. He put it very well -- and beat me to it! Yes in the ideal model, the attenuation factors multiply, and thus the decibels add up, but like he said, there are real-world non-ideal factors like leakage.

However, your hearing is logarithmic as well IIRC, so if the power is halved (6dB), it would not actually be a significant drop in perceived noise.