There are many products designed to protect shooters' ears from the very real dangers of gun sounds. Not all of them do a good job.
by Derek Partridge
Originally published in Gunfacts, January 1970
The problem of hearing loss, suffered by shooters of all types of firearms, has been the subject of an increasing number of articles recently in shooting publications and a subsequent increase in advertisements, each with their own claims to solving the problem. That there is this growing awareness of a long existent problem, which has long been ignored, out of bravado or ignorance on the part of shooters, is all to the good. However, being one of many shooters who has a definite hearing loss from shooting, I was still not satisfied that the articles had covered the subject sufficiently to give shooters the information they needed to protect themselves adequately, nor that all the advertisers' claims would stand up to expert examination and testing techniques.
Readers familiar with my articles in other shooting magazines will be aware that I normally give personal opinions about a subject that I know well -- International Trap and Skeet. In the field of sound attenuation (reduction for hearing protection), I am no expert. Accordingly, I called on the services of experts in the field who had no commercial bias whatsoever. This article represents a summation of facts supplied by them and their opinions, not mine. However, their opinions are not to be construed in any way as being given from an official capacity in their governmental occupations. They gave their opinions as personal ones, gained from much experience and research with hearing protectors. Their views do not constitute U.S. Government or Armed Forces endorsement of any product mentioned, nor do they necessarily reflect governmental policies relating to hearing protectors.
The final draft of the manuscript was submitted to them and received their written approval that it was a fair and accurate representation of their views, unless qualified in the text as my view or opinion. The principal experts consulted were: Paul C. Boettcher, a Qualified Industrial Hygiene Engineer, who holds the position of Senior Safety Engineer of the Division of Industrial Safety of the State of California; Raymond J. Theep, B.A., M.P.H., R.S. and Zane H. Martin, industrial hygienists working for the U.S. Government and· the Armed Forces, also in California. Industry has a far greater and ever-increasing problem of noise-protection and has therefore spent far more time and research on the problem than anyone strictly in the shooting field.
Industrial hygienists are concerned, among other subjects, with the design and evaluation of control methods aimed at protecting the health of workers, with respirators, ventilation systems, personal hearing protectors and radiation monitoring systems. These three experts, from their own personal interest, happen to have made a very deep study in the hearing protection field, for it is a problem of such magnitude that it daily affects more and more people, even out-side industry, in every walk of life. Their four years of intensive research and testing have covered the following items:
Earmuffs...............................34 models
Earplugs
(15 pressure, 3
one-time molded, 2
custom-molded)...................20 models
Helmets..................................6 models
Earmuff-earplug
com-
binations.................................6
models
Communication sets................3 models
There are many products designed to protect shooters' ears from the very real dangers of gun sounds. Not all of them do a good job.
In all, they investigated 69 different methods of hearing protection. In addition, they also shoot trap, skeet, rifle and pistol and so are especially well versed to apply their general knowledge of hearing protection to the specific field of shooting.
Beyond industry's concern in wanting to protect its workers and also obtain maximum efficiency from them (for excessive noise reduces both efficiency and output), is the usual hard cash motivation. Compensation for total hearing loss in the average skilled worker starts around $26,000 and goes on up, hence the amount of time and money spent to resolve the problem, from which we shooters can benefit.
The first National Legislation has just been introduced in the form of the Walsh-Healey Public Contracts Act, which requires protection for workers involved in Government Contracts of over $10,000, in two categories: I) Exposure to steady noise of over 90 dBA for 8 hours. 2) Exposure to impact (sudden) noise of over 140 dBA. In both cases, the employer is required to supply, and the worker to wear, hearing protection devices approved by the government. The present California State Noise Control Orders are stronger than the government requirements, another reason for selecting California for this survey. All protectors approved for industrial use in California must meet established criteria based upon the United States of America Standards Institute Specification Z24.22.I957, Measurement of the Real-Ear Attenuation of Ear Protectors at Threshold. (Note: dB is the abbreviation for decibels, the unit of measurement of a sound's intensity. dBA is a measurement which does not include the low frequency range of 0 - 400 Hz [(Hz is the international symbol for cycles per second)] , since for industrial purposes, loss in this range should not affect speech reception. Therefore a dB rating figure can be slightly higher than a dBA figure for the same sound, if that specific sound registers in the low 0 - 400 Hz range.)
Shooters are subjected to impact noise: In the case of shotgunners, around 140 dB, and for rifle and pistol shooters, nearer 155 dB. These are highly damaging noise levels which are equivalent to more than 140 dBA. Protection from damaging noise is a difficult problem, as each sound is composed of different frequencies. Different materials used for protection attenuate (diminish) different frequencies. So far, no one material will give complete protection from all frequency ranges and research has not yet shown which special materials attenuate best in specific frequency ranges. Therefore, most designers have aimed at providing the best possible coverage in the 125 Hz to 16,000 Hz ranges. Researchers still have a long way to go in this field and there are many divergent opinions held among non-specialized members of the medical profession. Even theories considered valid as recently as ten to fifteen years ago, are now out-of-date. The evaluation of attenuation is also a difficult job, requiring highly skilled knowledge and equipment. Often, items found to be good attenuators, turn out to be impractical in use -- as will be seen later. Additional problems are caused by bone and body conduction of sound, rendering total protection virtually impossible. The two facts everyone in the field agrees on are that lack of protection will result in hearing loss and that loss is absolutely irreparable.
The following are industrial requirements, out as their needs can be considered greater than shooters, due to being an "8-hour-a-day" problem, they will obviously cover shooters' needs, too:
1) Good
attenuation, i.e.:
reduction of
dangerous sounds to a safe
level, but permitting voices to come through the background
noise.
2) Good fit of a proven
good attenuator, without
any air leaks. An air
leak is the greatest enemy of proper attenuation, as a
passage
of air equates with a passage of sound and so nullifies the effect of
the attenuator.
3) Good memory return: this
means that the plug must not remain in the
"deformed" state that it will assume when pushed into
the ear canal,
but must return to its original shape after removal.
4) Ease of use and comfort
of item when worn, to insure continued,
correct use. This means something that cannot be put in
the wrong ear,
upside down or back to front and is so comfortable that the wearer does
not feel compelled to remove it before leaving
the danger zone.
5) Non-toxic:
meaning the absence of any
adverse reactions of the skin
in the ear (i.e. dermatitis), to the materials from which the earplug
is made. .
6) Long life, so
that the device may be used over an extended period of
time without deforming, shrinking, hardening or deteriorating.
PRESSURE
PLUGS.
These standard, round,
straight plugs all share one major disadvantage,
whether they come in one universal size or up to six different ones: No
two human ears are the same, but are as individual as finger prints.
Not even do any person's left and right ears have the same internal
characteristics -- a glance at the accompanying photographs will
provide
eloquent evidence of this. Irrespective of whether one or six sizes
are used, industrial experience shows that a maximum of 25% of people
fitted with pressure plugs will be comfortable and of them, only two
thirds will also have adequate attenuation. Jack B. McElhiney, one-time
head of the Industrial Hygiene Division of San Francisco Naval
Shipyard, goes even further and feels, from his experience, that
pressure plugs will fit only 5% of people and that the remaining 95%
will either experience pain, fail to achieve proper attenuation, or
both.
To fit pressure plugs in at all, you have to pull the ears to open them
and to try to straighten the normally curved, flattened or oval
interior canals so they will accept the pushed in hard to fill the ear
canals and seal them from air leaks.
This naturally causes a build-up of internal air pressure and
skin-contact pressure which bring discomfort, pain or an "earache". The
end result is that the industrial user removes them and so defeats the
whole object.
The air pressure is caused by the insertion of the plug, driving air
before it. This creates an airpocket, of greater pressure than normal
outside atmospheric pressure, pressing directly against the eardrum.
This in turn MAY be the cause of the dizziness and feeling of loss of
equilibrium of which shooters occasionally complain. Generally they
attribute this to wearing a solid ear plug, which they believe
prevents air from getting through to the center of balance. This was
also a commonly-held belief among the medical profession and is still
held by some who have not updated their knowledge.
In fact, the inner ear, which controls our balance and equilibrium, is
a sealed unit inside the also sealed eardrum, so air has absolutely no
effect on it. All you achieve by allowing passage of air to your ear,
is to open the door to the dangerous sound waves, which are also let
through.
The skin-contact pressure of plugs constricts the, blood flow through
the capillaries in the skin surface of the ear. The physiological
explanation is that the body cells respond to oxygen starvation by
producing a chemical called a kinen, which causes a pain sensation --
just
like the pain caused by ill-fitting glasses or dentures.
In fairness to shooters,
mention must be made of one pressure
plug
that has long been advertised and sold as the shooter's earplug, with
advertisements stating that they were" ... acclaimed by champion
shooters and recommended by hearing specialists.... and...
eliminate
the harmful effects of gun blast noise." I now learn that these have
been rejected as unsuitable, not only by the California Division of
Industrial Safety, but also by the U.S. Armed Forces, for the following
reasons: Unreliability of valve-closing mechanism at certain levels of
both impact and continuous noise; inability to fit enough people
through having only one size; the medical hazard of accidental blows
occasioned by the main body of the plug being metal (covered in
rubber); further medical hazard of distortion and distention of the ear
canal when inserting the plug; the fact that the valve can easily be
put out of action by anyone, or combination of the following: ear wax,
dirt, dust or moisture. The same company also markets two other
pressure plugs, which, although subject to the same disadvantages of
all pressure plugs, are nevertheless good attenuators and were approved
by the same authorities that rejected the one described above.
EAR
MUFFS:
With these, it is
possible to obtain nearly 100% protection,
if a number of factors are observed. The most important is that a
pressure of 3 - 4 p.s.i. (pounds per square inch) is maintained on each
side, in order to maintain a seal which is airtight and therefore
guarantees proper attentuation. This is how those muffs which are
acceptable to industry are originally designed. Unfortunately, this
pressure is such that it is generally uncomfortable and results in
headaches. People are often seen stretching them apart until the
pressure is bearable, at which point the air-seal will have been broken
and the muffs unwittingly rendered ineffective.
The muffs should also be the type which are worn with the band over the
head. When worn with the strap behind the head, the weight of the muffs
is often too much for the necessary pressure to be maintained.
Further
problems of maintaining adequate sealing and pressure can be
caused
by unusual facial bone structure or by wearing glasses. Both have been
partly overcome by the use of liquid sealing rings, filled with oil or
glycerine, but, they have an unfortunate tendency to leak.. Sponge
rubber also provides an effective seal, but is subject to
imperceptible deterioration through sweat and wear. It is therefore
extremely hard to know at what point the seal is no longer effective.
If the internal cup size is too small and squashes the ear, this also
will prevent proper sealing. Apart from causing headaches, muffs are
hot and sweaty to wear and can cause heat rash. Jack McElhiney also
cites cases of dermatitis, inflammation of the skin.
CUSTOM-MOLDED PLUGS:
This last major group of hearing protectors is the smallest, but most effective and acceptable from every aspect of both industrial and shooting application. They are made to fit the individual by the simple means of taking molds of the two ear canals with a quick-setting, soft, rubbery material. Then are cast female molds, from which, in turn, the final fitted plugs are made. Custom plugs should never be made of the hard materials which are often used in fitted hearing aids, since the intention of a hearing aid is not to prevent sound entering, but quite the reverse. Even some of the materials used by hearing aid manufacturers,"which are termed "soft", are still too hard for attenuation purposes. They would cause bruising with movement, which brings pain, which equals distraction, aggravation and fatigue, all of which equal missed targets for shooters. Why doesn't this affect hearing-aid wearers similarly? They only wear them in one ear and learn to immobilize one side of their faces, which is why they often appear to be speaking out of the side of their mouths.
A proper custom fit can only be obtained by using a soft material, which, as it slips gently into place, gradually lets the air out of the canal. This prevents the formation of the pressure pocket created by standard pressure plugs because the air left between plug and eardrum has been equalized to the same pressure as the outside air. The material should also be such that it softens further under the heat of body temperature and so molds itself even more perfectly into the ear, allowing the user all normal facial movements of talking, eating and drinking, without any bruising or even discomfort. The outer portion should be of a harder material to hold the plug firmly in position in the form of the outer ear. (A further advantage of custom-fitted plugs, is that even if the instructions are lost, there is only one way each plug will fit in the ear -- the correct way.)
As far as the panel of experts I consulted know, there is only one such product available today, which has all these characteristics and also provides satisfactory attenuation. It is called the Soundown and is used, for example by I.B.M., United Air Lines and at the N.A.S.A. Ames Laboratories at Sunny-vale, Calif., where they have nearly 100% employee acceptance and satisfied continuous use. This compares with a mere 15% acceptance figure for other plugs and 30% for muffs. (The higher figure for muffs results partly from the fact that they are supplied in areas where noise is at such a high level as to be obviously damaging to personnel working there, as opposed to other areas where it does not appear to be damaging to the average, uninformed worker.) The industrial hygienists found that the Soundowns can be worn for hours, without any discomfort, to the extent that workers even forget they are wearing them. The plugs have been worn for as long as seven years (the length of time the product has existed) on this daily basis, without any deterioration. Edgar DeMar M.D., Regional Medical Director of United Air Lines, San Francisco, after months of research, concluded in his report on Soundowns, published in Industrial Medicine and Surgery: "We have been introduced to a new type of ear plug that seems to have ideal characteristics."
Ear muffs, in good condition, work well. Key points: There must be an airtight seal all around, and the muffs must not be dislodged by, for example, brushing against a gunstock. The required 3 - 4 p.s.i. pressure for the seal is not easily maintained by the behind-the-head type.
One custom-molded plug that works well is the Soundown. The success of this plug seems related to the fitting accomplished by the maker, which allows both proper attenuation of sound and comfort for the wearer.
It's much the same with unprotected eyes: I never liked to wear glasses, as I don't need them optically and would only wear them for skeet (where there is the possibility of a fragment from the first of a pair of doubles striking your face, while you are concentrating on breaking the second); any time I used an automatic (where there is the ever-present chance of blow-back of partly, burnt particles of powder, during the shell-ejection phase); and anytime there was a head-wind (when muzzle blow-back particles from either your own or a competitor's gun could hit you in the eyes at a crucial moment). Then, in the hot California sun and the hotter Texas sun, I found eye-fatigue could be caused solely by the strong light of the sun. Throughout the day, my eyes would become progressively more bloodshot and painful, causing me to strain them more and more, to focus on fast-moving International Trap targets. The resultant fatigue and irritability had their obvious effect on my performances, which inevitably trailed off through the day. Since wearing proper protective lenses, this pattern has not repeated itself!
A further pertinent suggestion comes from Jerry Eisen, another California State Qualified Industrial Hygiene Engineer: Indoor rifle and pistol range operators should consider sound protection when designing new facilities and even with existing ones should insure the maximum use of sound-deadening material in such places as between shooting stands or booths. Also, on both indoor and out-door ranges, operators should insure that their personnel are as protected as the shooters, for they are subjected to far more potentially damaging sound than the shooters.
As a closing thought to shooters and yet another factor for the importance of wearing good hearing protectors, the results of a unconnected, but relevant human behavioral survey, are of interest. To sum it up with a pertinent example: It was found that if a man is lying in the street moaning, he attracts far more attention and action on the part of passers-by than a man in exactly the same position, but lying silent. This was one of a series of tests which showed that our emotions are more influenced by what we hear than by what we see. As shooters, we are subjected to visual distractions, which can range from a fly on the barrel to an emerging trap boy's head, but how often have we heard the deliberately-not-very-low whisper that reminds us clay busters that we are "going straight"? Even if it is a perfectly innocent remark by a disinterested bystander, it is much harder to put out of our heads than any visual distraction, and I'm sure we can all remember more than one such occasion that blew a straight!
Originally published in Gunfacts, January 1970