Doubling Muffs and Plugs

Discussion in 'General Firearms Forum' started by -JCN-, Jul 30, 2018.

  1. -JCN-

    -JCN-

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    I like this article:

    https://www.audiologyonline.com/articles/extra-protection-wearing-earmuffs-and-1218

    Extra Protection: Wearing Earmuffs and Earplugs in Combination
    Elliott H. Berger, MS, INCE Bd. Cert.
    August 6, 2001

    INTRODUCTION:

    When it's really loud, so loud that a properly worn single hearing protection device (HPD) can't provide safe listening, what is a hearing conservationist to do? Reducing exposure time or other administrative controls are certainly options to consider. Another option may well be the use of earmuffs and earplugs in combination, commonly called 'dual protection.' As you probably guessed, dual protection has its own assets, liabilities, and limitations. This article will explore them.

    OVERVIEW:

    It is generally recommended that one should consider the use of dual protection when 8-hour time-weighted-average (TWA) exposures exceed 105 dBA as required in the new Mine Safety and Health Administration (MSHA, 1999) noise regulation, which went into effect September, 2000. For an extra margin of safety one may wish to consider implementation of dual protection when exposures exceed 100 dBA as is suggested in the 1998 NIOSH Revised Criteria for Occupational Noise Exposure. Using dual protection at levels or exposures below that is problematic due to interference with speech-based communication. However, once noise levels exceed 100 dBA unaided speech communication (i.e. communication without electronic amplifiers and earphones) is nearly impossible anyway. Therefore, no additional detriment is created by the extra protection.

    Other difficulties in mandating the use of dual protection in lower-level noise include motivating employees to wear devices properly, and subsequent enforcement of their use. Although the 'annoyance' of a sound is not a good measure of its potential hazard or the need for hearing protection, its annoyance (or lack thereof) can substantially impact the ease with which use of HPDs can be mandated and effectively enforced. For many, exposures below 100 dBA just don't seem loud enough or annoying enough to warrant single protection -- let alone dual protection! If the sounds are not annoying, insisting on use of dual protection can be considerably more difficult than trying to obtain compliance with the use of a single product alone.

    PERFORMANCE CONSIDERATIONS:

    Earplugs worn in combination with earmuffs, helmets, or communications headsets, typically provide greater protection than either device alone. However, the attenuation of the combination is not equal to

    [​IMG]

    the sum of the individual attenuation values (Berger, 1983), as illustrated in Figure 1. Note for example; at 1000 Hz the combination of a 26-dB plug and a 34-dB muff does not yield 60-dB overall, but rather about 41 dB. The principal reason is the bone-conduction (BC) limits to attenuation, which are also illustrated in Figure 1. The BC limits represent sound that effectively flanks or bypasses the HPD to directly stimulate the middle and inner ears of the wearer. Another limitation on the performance of dual protection is that the plug and muff interact mechanically with each other, and thus do not behave as two completely independent attenuators.

    No empirical or theoretically derived equations are available that can predict the attenuation of an earplug and earmuff combination with sufficient accuracy to be useful. At individual frequencies the incremental gain in performance for dual hearing protection varies from approximately 0 to 15 dB over the better single device, but because of the dip in BC limits at 2000 Hz, the gain varies from 0 to only a few decibels at that frequency. Attenuation changes very little when different earmuffs are used with the same earplug, but for a given earmuff the choice of earplug is critical for attenuation at frequencies below 2000 Hz. At and above 2000 Hz, all dual-protection combinations provide attenuation essentially equal to the limitations imposed by the bone-conduction pathways, approximately 40 to 50 dB, depending upon frequency. As a rule of thumb, the OSHA procedure of computing the dual protection by adding 5 dB to the Noise Reduction Rating (NRR) of the more protective of the two devices is a reasonable approximation.

    For the best estimate of dual-protection performance a real-ear attenuation at threshold measurement of the combination being evaluated should be conducted. Some manufacturers of hearing protectors can provide such data. Better yet, real-world attenuation values should be considered (Berger, 2000). Unfortunately few of those types of data are available. One study, of which the author is aware, suggests that the highest attenuation in terms of an NRR-like number, that can realistically be obtained for about 84% of the population, is about 25 dB (Hachey and Roberts, 1983). This was observed in one study of a foam earplug worn in combination with a small-volume plastic earmuff. Thus when TWAs exceed about 110 dB, even dual protection is likely to be inadequate. At such times, limited durations of exposure and twice-annual monitoring audiometry should be considered.

    The use of dual HPDs is especially recommended when high-intensity noise is dominated by energy at or below 500 Hz since it is in this frequency range that the attenuation of single HPDs will be the least and the potential benefits from dual protection are the greatest.

    APPLICATION CONSIDERATIONS:

    For maximum protection not only must a muff and plug be worn together, but both devices must be worn correctly and consistently. Even short periods of disuse can dramatically reduce the effective protection. At low frequencies, the earplug can be the most important part of the combination and thus its correct use is vital. Individual training is especially important for the high-noise otohazardous areas in which dual protection is likely to be worn.

    Another issue is the ability to monitor correct usage. This is complicated once the muff is in place since the fit of the plug cannot be readily assessed by supervisors unless they stop and ask the employee to lift one or both earmuff cups. In fact, when dual protection is apparently being used, whether or not the plug is actually being worn at all cannot be ascertained by simple passing observation. An interesting

    solution to this problem has recently been provided by one manufacturer in the form of clear earmuffs with a special donut-shaped foam absorber inside that allows clear viewing of the earplug (see Figure 2).
    The absorber has been designed so as not to degrade the earmuff's attenuation, so that even if the muff is worn alone, it functions as well as its standard opaque counterpart.

    [​IMG]

    Figure 2: A new style of dual protection that incorporates the use of a foam earplug worn under a clear earmuff cup (Peltor/E#149;A#149;R High Performance Series).


    CONCLUDING REMARKS:

    It has been observed that 97% of industrial noise exposures are less than 100 dBA TWA. Therefore, in most cases, dual protection is not going to be necessary or appropriate. However, for

    those situations in which noise exceeds 100 dBA, as found in a wide range of industries from on-line aircraft engine maintenance to metal riveting, dual protection may be an appropriate solution.

    Although the casual observer of HPD's labeled NRRs might conclude that in almost any noise exposure employees will be adequately protected (because labeled NRRs commonly range from 22 - 33 dB), that is far from the actual case. Many studies in the past 20 years have clearly demonstrated that in real-world environments HPD attenuation falls far short of the EPA-mandated NRRs that have appeared on packaging since the early 1980s (Berger et al., 1996). Thus in critical high-noise instances, where TWAs exceed 100 to 105 dBA, the use of dual hearing protection is warranted.
     
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  2. G26S239

    G26S239 NRA Patron

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    On the flightline we would wear double ear protection when standing near the Huffer or APU while they were operating. The BC or cone conduction is a good thing to consider as well. That's why I wear mickey mouse protection indoors and when shooting the 460XVR. Good article JCN.
     
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  3. Diesel McBadass

    Diesel McBadass Tactically Epic

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    I wear electronic muffs over foam plugs. A solid combo.
     
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  4. CBennett

    CBennett

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    lately same...especially when shooting the AR and especially if its at the INDOOR range. outdoor with 9mm i can do my good earmuffs but inside i use both.
     
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  5. checkyoursix

    checkyoursix

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    I do it when I SO carabine matches, or when I SO a match with a lot of walls, barrels and the like.

    Eargasm (didn’t make that up, sorry) plugs are very good for that, they are thin, easy to double.
     
  6. fnfalman

    fnfalman Chicks Dig It

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    I've been using double hearing protection for years now. Especially ever since that I lost half of my hearing in my left ear due to an infection, I want to protect the rest of my hearing for as long as possible.
     
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  7. megawatt

    megawatt Electron maker

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    Wear both when shooting. Especially with long guns because most ear muffs get pushed up and lifted off your ear when shooting a rifle.
     
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  8. Maccabeus

    Maccabeus

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    I double up when shooting at indoor ranges.
     
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  9. Diesel McBadass

    Diesel McBadass Tactically Epic

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    Im exposed to excessive noise as part of my job as it is. Take no chances with my hobby. Some people hate hearing protection and never wear it. i dont get it.
     
  10. ChuteTheMall

    ChuteTheMall Wallbuilder and Weapon Bearer

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    My ears started ringing during Clinton's first term, and it's never stopped.:notlistening:

    I wear muffs over molded plugs most of the time indoors, sometimes only one or the other outdoors depending on who else is there.
     
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  11. WeeWilly

    WeeWilly

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    Excellent idea for anyone shooting. Tinnitus and the general hearing loss that comes with exposure to high sound levels is not only not fun, but generally preventable when proper protection is consistently followed.
     
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  12. VinD

    VinD

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    I double up in and out to protect my ears.
     
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  13. Darkangel1846

    Darkangel1846

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    As a person who has a sever High Freq hearing loss that has now progressed into lower freq. I can not endorse the wearing of double hearing protection enough. Once your hearing starts to go is becomes a royal PITA! Had to retire early because of it, have to wear hearing aids that do not help that much, people avoid talking to me as I say please repeat what you just said way too much. I have to use head phones when watching TV as I would have to have the TV way to loud without them. I can't hear the doorbell, sometimes I can 't hear the phone, have to have my cell on vibrate on my hip. If more then one person is talking I can't understand either one of them. Background noise does the same.
    Using the phone is terrible, and if people talk fast I can't understand them.
    Protect your hearing at all cost!
     
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  14. techiej

    techiej

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    I always double up when shooting indoors or if there are others shooting rifles outdoors...Otherwise I just use ear muffs.
     
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  15. Paul7

    Paul7

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    I always double up, and only shoot outdoors.
     
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  16. Judge Bean

    Judge Bean

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    I double up at the range where people bring some big noise-makers. Those muzzle brakes are really nasty. Alone in the woods, one set is good enough.
     
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  17. China boy

    China boy

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    Its effortless to double up so why not. Plugs plus electronic muffs are a great combo.

    You never know what the guy next to you at the range is bringing. My one buddy only shoots .22 and tells me how he goes to an indoor range with people shooting ARs next to him. Haha.

    Always better to over do it with protection rather than not.

    I do this combo. Works very well for not too much spent.
    https://www.amazon.com/gp/product/B007FKY86K/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1

    https://www.amazon.com/Electronic-S...s&keywords=howard+leight+ear+protection&psc=1
     
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  18. DonD

    DonD

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    I've been wearing double ear protection for many, many years on everything louder than a .22LR rifle, there, plugs are in my view, quite adequate. Double protection for .22LR handguns.

    I also find that while the main reason for double ear protection when shooting my 500 Mags is saving hearing, I find that the lowered noise level at my ears reduces the perception of recoil, reduces the tendency to flinch occasionally and makes it more fun. Don
     
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  19. geefal

    geefal

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    I started 20 years to late, but now do the combo setup also. Trying to save that last 20% of hearing I have left. :crying: Would literally beat the living snot out of the "young" version of me for all the stupid problems he saddled me with. Galldang idiot he was, thinking he was going to live forever and nothing was going to affect him.
     
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  20. Borg Warner

    Borg Warner

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    Doubling up on ear protection helps the shooter to relax and concentrate on aim, grip. stance, and other fundamentals and helps new shooters most of all.

    Behaviorists and neuroscientists say that we are born with only two innate and primal fears: Fear of loud noises, and fear of falling. All other fears, fear of spiders and snakes, claustrophobia etc, are learned fears.

    And even if gunfire doesn't actually scare you, it does cause an instinctive reaction and my personal experienced is that I am much better able to focus on my shooting when I double up on hearing protection
     
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