Hearing protection vs. hearing damage

[PinnedAndRecessed]

Facts on noise levels:

Decibels measure sound pressure and are logarithmic, a 3db increase almost doubles sound pressure, a 6db increase quadruples sound pressure.

Gradual hearing loss may occur after prolonged exposure to 90 decibels or above.

Exposure to 100 decibels for more than 15 minutes can cause hearing loss.

Exposure to 110 decibels for more than a minute can cause permanent hearing loss.

Here are some examples of noise levels:

Video arcades - (110 dB).

Firecrackers - (125-155 dB at a distance of 10 feet).

Live music concerts - (120 dB and above).

Movie theatres - (118 dB).

Health clubs and aerobic studios (120 dB).

Sporting events (127 dB).

Motorboats - (85-115 dB).

Motorcycles - (95-120 dB).

Snowmobiles - (99 dB).

"Boom cars" - (140 dB and above).

Here are noise levels of firearms:

.223, 55GR. Commercial load 18" barrel 155.5dB

.243 in 22" barrel 155.9dB

.30-30 in 20" barrel 156.0dB.

7mm Magnum in 20" barrel 157.5dB.

.308 in 24" barrel 156.2dB.

.30-06 in 24" barrel 158.5dB. In 18" barrel 163.2dB.

.375 18" barrel with muzzle brake 170 dB.

.410 Bore 28" barrel 150dB. 26" barrel 150.25dB. 18" barrel 156.30dB.

20 Gauge 28" barrel 152.50dB. 22" barrel 154.75dB.

12 Gauge 28" barrel 151.50dB. 26" barrel 156.10dB. 18" barrel 161.50dB.

.25 ACP 155.0 dB.

.32 LONG 152.4 dB.

.32 ACP 153.5 dB.

.380 157.7 dB.

9mm 159.8 dB.

.38 S&W 153.5 dB.

.38 Spl 156.3 dB.

.357 Magnum 164.3 dB.

.41 Magnum 163.2 dB.

.44 Spl 155.9 dB.

.45 ACP 157.0 dB.

.45 COLT 154.7 dB.

Properly fitted earplugs or muffs reduce noise 15 to 30 dB. The better earplugs and muffs are approximately equal in sound reductions, although earplugs are better for low frequency noise and earmuffs for high frequency noise.

All of us should be trying to get the greatest Noise Reduction Rating (NRR) that can be put together. NRR 30 plugs with NRR 20 muffs will give you an effective NRR 45 (add plugs and muffs, then subtract 5). If noise levels are 160 dB this gives you an exposure with plugs and muffs of 115 dB. The acceptable exposure time for this is 15 minutes total for the day. If the noise levels are 150 dB the resultant acceptable exposure time with the given plugs and muffs is 1 hour and 4 hours if the noise level is 140 dB. You're not going to find unsuppressed noise levels below 140dB with gunfire.

If you are shooting by yourself, roughly 100 rounds of 140 dB instantaneous noise in a day should not produce hearing damage. Put your plugs and muffs on and you get to shoot up to a thousand rounds without damage (louder ammo/gun and the allowable drops by a factor of 5). Shoot with other people and you have to add all the rounds shot cumulatively (10 people shoot 100 rounds and everybody's done for the day; toss a handcannon or 30 cal rifle in and you're back down to 200 rounds cumulative). If you shoot on an indoor range then all the rounds fired while you are on the range go into your total. So you can see that it doesn't take very long on a range to have a thousand rounds popped off around you.

If you want to know what the noise level you are exposed to is you can rent noise dosimeters that you can wear. They will record the total noise exposure and present the information to you as dB. You can then subtract the adjusted combined NRR of your hearing protection to determine if you're getting too much exposure.

[Ledbetter]

Excellent information.

[warwagon]

That was indeed excelent information, sadly for me too late.

I can testify to any young shooters out there to please use the hearing, and eye protection at all times!

As a 51 year old, and having been around a number of rounds going off without protection, I can attest that tenitus is no fun.

It dosen't matter that some of theese were in police combat situations, the final truth is it happens.


P&R, +10 for forwarding that info!

Now we can only hope that the newer (and in some cases older) shooters listen to what you have to say.

Best regards,

Blair

[rnovi]

I ride a motorcycle and I can tell you that earplugs are absolutely vital. Not only is riding loud, noise is also a very serious contributor to fatigue.

One question I have is whether or not the decibal ratings were taken from in front of the barrel, to the sides, or behind. The location of the reading makes a huge difference. Standing behind the barrel when a shot is taken (as opposed to the side, such as two hunters side by side...) makes a huge difference in the noise.

I personally use a set of baffled earplugs when I hunt. In the outdoors, it's just enough to cut the report of the gun but not enough so that I can't hear the call of the animals.

You only get one set of ears. Protect them.

[Eghad]

hearing protection if you got it wear it

if you dont have it, dont shoot without it

Im 50 with hearing loss......

[#18indycolts]

rnovi-lemme guess, you ride a harley,no helmet and no baffles! I can see why you need earplugs! As for me, a stock exhaust and an excellent helmet make for a quiet ride...but when you rev to 13,000+ and going over 150mph thats a diff. story! btw, i ride a '05 gsxr1000.

[rnovi]

No HD here. I ride a 1995 BMW R1100RSL in Dakar Yellow. Previous bike was a ZX11. trust me, I know speed . I just had to slow down...
Believe me when I tell you, it's a lot louder on that bike than you think. Noise fatigue for me sets in around three hours - most of my rides cover over 500 miles..

PS: We now return you to your regularly schedule thread-jacking...

[SIGSHR]

I tell new shooters that their first purchases must be eye and ear protection, then they start looking at firearms. I have been wearing plugs and
muffs for years, I wear hearing protection when I use power tools, at age 56
I actually think my hearing is getting more acute.

[BIGR]

Great Info....For years I never worried much about hearing or eye protection while I was blasting away with the guns. Since I have got older I try to use both eveytime I shoot.

[FirstFreedom]

Thanks for the info. No wonder my brother lost some hearing from a .357 mag with no protection. I wonder if a ".375" rifle with muzzle break means a .375 H&H mag, or some other .375....

[xjmox14x]

Yea, I just went shooting this weekend. I had never shot a .308 before and I had just gotten one. I shot it without hearing protection for the first shot, to see just how loud it really is. It was weird....it was loud, but it didn't really hurt. However, I did notice a slight ringing in my ears and I knew I'd be done if I had done it all day. So I slapped some earmuffs on and I was good for the rest of the day.

[Flavio]

I already have the muffs already and Im gonna buy myself the earplugs as well

[Double Naught Spy]

All of us should be trying to get the greatest Noise Reduction Rating (NRR) that can be put together. NRR 30 plugs with NRR 20 muffs will give you an effective NRR 45 (add plugs and muffs, then subtract 5).

Where did you get this NRR formula? What is the reasoning to add the levels of protection and then subtract 5?

Why would you use 30 db nrr plugs but only 20 db nrr muffs? Why aren't you using better muffs?

For the ease of simplicity, assume you had 30 db nrr plugs and 30 db nrr muffs. According to some folks, the combined use results in only a 33 db nrr. The reasoning is that since db pressure doubles with every 3 db increase, then with doubled equal protection, the additional db nrr reduction only changes by 3 db.

The math seems correct, but it is based on a single point barrier for reducing sound and this is not the case when you use multiple barriers such as plugs and muffs combined that provide a sequence of noise reduction.

For a given sound level, say 150 db, the 30 nrr muffs would reduce the noise to 120 db that gets past the muffs. The 120 db then encounters the second 30 db barrier and then the sound is reduced by another 30 db that leave you with 90 db going into the inner ear. With two barriers, the second barrier has no knowledge of how much sound (pressure) has already been reduced. In fact, it has no idea if another barrier was present. The second barrier, the plugs, simply work with the sound they encounter regardless of how that sound was manipulated on the way to the plugs.

[kesserman]

With two barriers, the second barrier has no knowledge of how much sound (pressure) has already been reduced

I have wondered about this as well....

Some may say that you only get 3db additional protection due to operator error.

[Don P]

We go through this at work. You folks are giving false info here!
The way it works is when using muffs and canal plugs if one is rated at 31 and the other is rated at 33 you add 5db to the higher of the two ratings and that is the level of protection. Anyone that disagrees with this, can look at any safety product suppliers catalog and it will be explained in the hearing protection section. This has been learned at our company safety and OSHA seminars, along with testing our employee's yearly as part of our hearing conservation program.

[Double Naught Spy]

First, 22-Mag, how much hearing protection is afforded by different materials and barriers is not reflected in the testing of employees' hearing. You may be able to determine if the hearing protection afforded is working or not, but not how much hearing protection is provided by layers or materials. Why? Becuase hearing loss is a cumulative event that occurs over time, and can occur outside of the work environment.

Since you are up on the OSHA standards and facts, if you are operating a piece of equipment that is encased in a sound absorbing chamber that effectively reduces the noise level by 33 db but is still producing 140 db of sound that comes through that barrier to the operator's (your) position and you are wearing muffs that reduce noise by 31 db, how much sound is getting to the ear? By your information, the doubled protection would result in only another 5 db in reduction and the person wearning the muffs would be getting 135 db.

I love the math aspect. if you double the protection of a single barrier, you get a reduction of just 3 db because of the log scale whereby pressure doubles every 3 db. What you are claiming is that whether slightly more than doubling or slightly less than doubling the protection, you are geting 5 db more protection, not 3. That means that pressure is reduced by half with the first 3 db of reduction then another significant amount for the extra 2 db.

Please tell me how it is that the 31 db nrr muffs are not reducing the noise penetrating the muffs by 31 db and instead would only be 5 db.

Or is this a project of some mystical relationship between plugs and muffs? If so, please explain.

I have spoken with two audiologists who have both explained to me the apparent accepted normal that in wearing muffs and plugs, say they are both the same rating, reduces the sound to the ear by only another 3 db because sound level is cut in half by the double protection. Neither could knew or could explain if the NRR calculations and 3db pressure reduction was calculated using a single barrier or multiple barriers or how it is that sound passing through one barrier knows to only reduce by a small amount (either 3 or as you suggest, about 5 db) versus sound of the same exact level only passing through one barrier and being reduced the full 30 db amount.

Just how does 170 db sound reduced to 140 by a barrier know to reduce by only another 3 or 5 db when passing through the next 30 db barrier versus 140 db sound that hits only one 30 db barrier and knows to reduce to 110 db.

If you can come up with a source other than product packaging, please let me know. I am not an audiologist, but the facts and figures don't seem to work and the info you provided doesn't fit the info the others provided.

[Don P]

I'm not looking for a flame war here. I just stated thing learned from company provided training. I am providing this info for all to read. There are many more studies out there if any of the members choose to search them out and here for your reading pleasure, I would like to draw your attention to the paragraph titled Limitations of Protection. I also did not state this was learned from testing employee's hearing. I stated we test there hearing as part of our hearing conservation program. Maybe you need to go back and read my first reply.

Lend an Ear to Hearing Protection

Dennis Zeimet, Charles V. Schwab and Laura Miller
Iowa State University Extension


Table 1. Common noise levels (in decibels)
Jet airplane 140*
Pig squeals 130*
Chain saw 115
Loud rock music 115
Chickens (inside building) 105
Table saw 100
Shop vacuum 98
Garden tractor 92
Tractor wearing HPDs 85-95
Lawnmower 85
Electric drill 88
Quiet whisper 20
Note: Each increase of 6 decibels doubles the noise level
* Above 130 decibels causes pain.

The traditional picture of a farm as a serene and quiet workplace couldn't be farther from the truth. Machinery, even sounds made by animals, create a sometimes noisy and often hazardous environment.

The noisy farm environment has taken its toll on many farm operators' hearing capabilities. A central Iowa farm health clinic found that 70 percent of farmers given a routine hearing test had below normal hearing for their age. At least 30 percent suffered hearing loss significant enough to warrant an assistive hearing device.

Table 1 is a chart of sounds commonly heard by people involved in agricultural activities. Continuous sounds of 85 decibels or higher are considered hazardous. Any time you have to shout to be heard by someone standing 3 feet away, the noise level is probably greater than 85 decibels. Every 6-decibel increase doubles the sound. For example, a table saw (100 decibels) is twice as loud as a garden tractor (92 decibels).

Distance from the noise source also is important. As a person moves away from the sound, loudness drops off quickly. For example, someone 9 feet rather than 3 feet away from a chain saw will hear 103 decibels and not 115 decibels. The key is to keep noisy equipment as far away as possible. When that's not possible, wear hearing protection devices (HPDs) to get noise within the acceptable 85-decibel range.


HEARING LOSS

Some hearing loss occurs naturally as part of aging. Generally this does not become severe unless people are continually exposed to noise. Therefore, it is important to avoid excessively loud noises to prevent additional hearing loss that could lead to a disability.
Hearing loss will occur even if people say they have become "used to the noise" or ignore it. Many people say they can "block out" noise, but damage will continue unless the hazardous noise level is reduced.

Although noisy environments can lead to permanent hearing loss, they also can affect people in other ways. Noisy environments can lead to increased anxiety, hypertension, and fatigue. Many people who wear hearing protection comment that they feel better in general at the end of the day.

Most people cannot detect their own hearing loss because auditory damage occurs slowly over time. Usually, a person with a hearing loss may think other people are mumbling and need to "speak up" or enunciate better. If in doubt, get a hearing test by an audiologist, available at most hospitals and clinics.


WHEN TO CONSIDER PROTECTION

Hearing loss can be prevented with the proper use of hearing protection devices (HPDs). These devices provide a barrier between the sound and the ear, or absorb sound waves before they enter the ear. Persons with normal hearing always can detect some sound while wearing HPDs because bones in the head conduct sound.
You may want to consider HPDs if:


you work in noisy conditions that have a continuous decibel level greater than 85;
you experience "ringing" in the ears after being in a noisy area;
you are bothered, nervous, or anxious after being in a noisy area;
you want to increase your comfort;
you are unusually fatigued after working in a noisy area, or
your doctor recommends one.

HOW TO SELECT PROTECTION

Not all HPDs provide the same level of protection. Consider the following aspects:
Style. The most common hearing protection devices are muffs worn over the ears, and plugs worn in the ears. Muffs may be more comfortable to wear for long periods of time than plugs. Muffs should not be worn with eyeglasses or any other obstruction that will reduce their effectiveness.

Hearing plugs may be disposable or designed for re-use. Disposable plugs are especially popular for short wearing periods or infrequent use. They are inexpensive and can be thrown away when the job is completed or they become dirty. However, disposable plugs can be relatively expensive if hearing protection is required on a regular basis. In this case, a non-disposable plug or muff, meant to be washed and stored after each use, is a good choice.

Effectiveness: Not all materials can block the same amount of sound. An HPD manufacturer must indicate how much noise (in decibels) the device will reduce for the wearer. This is listed on the package as the noise reduction rating (NRR). For general use, look for NRR of 25 or greater. Remember that the rating was obtained in perfect conditions after wearers had received careful fitting instructions. A more realistic estimate is about half the manufacturer's NRR. For example, expect a d vice with a 30 NRR to reduce noise by about 15 decibels. This means that a 95-decibel noise would be reduced to 80 decibels for the wearer.

Cost: Hearing protection devices do not have to be expensive to work well or be comfortable. Expandable foam ear plugs are available for about $1; muffs about $15-$30, depending on quality.


LIMITATIONS OF PROTECTION

As with most personal protective devices, HPDs have limitations. Improperly worn HPDs may not reduce the noise levels to within acceptable levels and tend to cause a false sense of security. Wearing both plugs and muffs at the same time will reduce the amount of noise exposure. However, the additional reduction from wearing both devices will be only 6 or 7 decibels, even if the NRR for both devices is above 25.
A dirty HPD can cause serious skin irritation and ear infection. Follow manufacturer's instructions to clean non-disposable HPDs, and keep in a clean, dry container. Washing expandable foam or disposable plugs can actually harbor germs and foster disease.

Wearing hearing protection devices may take some adjustment. At first, wearers may experience some physical discomfort after several hours. Upon continued use, these annoyances generally diminish. The long-term benefits -- diminished loss of hearing -- outweighs any short-term inconveniences from wearing HPDs.


HEARING SAFETY

How Much Do You Know?
Most hearing protection devices, regardless of type or design, reduce about the same amount of noise that reaches the ear. True or false?
An extended time in a noisy environment can make people feel anxious and fatigued. True or false?
The squeal of a pig has a louder decibel level (sound) than a rock concert. True or false?
Which of the following sounds could cause hearing loss?

an electric drill
a garden tractor
an enclosed poultry building
all of the above

It's more difficult to hear conversations in a noisy environment while wearing a hearing plug or muff. True or false?
Hearing muffs always block out more noises than hearing plugs. True or false?
See answers at the end of "What Can You Do?".

What Can You Do?

Identify jobs where the noise may be harmful to your hearing or bothers you.
Ask your local farm supply dealer to stock HPDs.
Wear hearing protection in any situation in which you must raise your voice to be heard 3 feet away.
Get a hearing test if you think you may have hearing loss or question your hearing ability.
Purchase a hearing protection device that will meet your specific needs. Follow the manufacturers' instructions for proper use and wear.
Answers to quiz:

1-False; 2-True; 3-True; 4-d; 5-False; 6-False


FOR MORE INFORMATION

If you're interested in purchasing a hearing protection device, check with your local farm supply store or a direct-mail catalog. An audiologist or hospital clinic also would be a good source. For more information about hearing protection devices, contact the National Safety Council (NSC) for a copy of a Rural Accident Prevention Bulletin: Hearing Protection in Agriculture, Catalog #69941-0006. You can write the NSC at 444 N. Michigan Avenue, Chicago, Illinois 60611. Cost is about $1.


Disclaimer and Reproduction Information: Information in NASD does not represent NIOSH policy. Information included in NASD appears by permission of the author and/or copyright holder. More

NASD Review: 04/2002

This document is Fact Sheet Pm-1518j , a series of the Safe Farm Program, Iowa State University Extension, Ames, Iowa. Safe Farm promotes health and safety in agriculture. It is funded by the National Institute for Occupational Safety and Health, Iowa State University, and a network of groups that serve Iowa farm workers and their families. Publication date: October 1993.
Prepared by Dennis Zeimet, industrial education and technology; Charles V. Schwab, extension safety specialist, and Laura Miller, extension communications. Design by Valerie King, Iowa State University Extension, Ames, Iowa.

[Dyaus]

Not to steal the topic, but what brand of muffs or plugs do you guys use? I'm looking to get some and wondered if you guys preferred one brand to another. Thanks.

[Chris Phelps]

"boom" cars produce from 120dB and up INSIDE the car. 140-150 is common for competition vehicles, again... INSIDE the car.


People who refer to cars with systems as "boom cars" most likely have never been in them, and therefore will probably assume that dB rating is OUTSIDE the vehicle. This would be quite false.


There are many errors on the origional post, but being a certified mobile electronics installer, that one caught my attention the quickest.


I have been competing since I was 16, and my current SPL record is 153.7dB. I can sit in the car for about 3 minutes fairly comfortably without hearing protection.

I think the frequency at which the SPL is achieved is equally as important as the level itself. For example, a quick 150dB burst at 2khz (where human ears are most sensitive) would leave your ears ringing for the better part of the day. A 150dB burst at 20hz-60hz (where car audio systems are loudest) will not have this same effect. Yet, this fact remains largly overlooked when these posts come up. I frequent a car audio forum, this forum, and a sportbike forum, and the subject comes up a lot.

With motorcycles, the high dB ratings are generated not by the bike itself, but by the noise of the wind passing into or under your helmet. I wear earplugs when I ride for this very reason... and often times, my ears will be ringing regardless.





How about a study of how the frequency and spl combined will affect our hearing, instead of relying solely on spl?


To further stress my point... here is one final thought. Many uninformed people think that the frequency has no effect at all. If this were the case... if you were sitting in a 3 x 3 cube made of steel, and someone blew a dog whistle (which has a frequency of about 40khz, generally... human hearing is 20-20khz.), you would actually go deaf. We all know, however, that this is not the case... since the sound is inaudible.

[Don P]

To answer Dyaus's question IMO purchase the best you can afford. Howard Leight makes many ear canal products. The ones I use are named MAX and they offer 33db of noise reduction. Combine these ear canal plugs with a set of ear muffs that offer 30db and you will obtain about 37-38db in noise reduction. If you plan on spending A LOT of time at the range then maybe you need to look at the muffs that use batteries. They will be in the 250-300 dollar range. For weekend shooting canal plugs and muffs will give you ample protection. If you like check my post from the Iowa University to give yourself more info to work with.. To sum it up, how deep are the pockets and how much range time.

[Sumner]

well this is my first post.
im from australia, and our gun laws are really strict. at ranges u must wear hearing protection.
i think its pretty common sense. when i first started off, i had plugs, later finding out they are pretty bad. i then purchaced some decent muffs, that have batteries in them, i can hear people talking in the range next to me but any loud noises it muffles. great muffs, and being young, and allready having to say "what" lots i want to protect my ears the best i can.

[Dyaus]

Lots of good information in this thread. Personally I like muffs better. The main reason being they are more comfortable for me. I don't like really like ear plugs to much, but it could just be because i've got some crappy ear plugs. They never seem to fit my ear good and sometimes start to back out of me ear. So I think i'll look for a good set of muffs.

[Don P]

More info for the non-believers, click on the attachmentshttp://www.e-a-r.com/hearingconservation/

[panino]

Prolonged exposure... does that mean that a single 12 gauge shot indoors would not cause permanent damage? I.e. a home defense occurrence?

[Double Naught Spy]

Yes. The damage may or may not be noticeable, but it will definitely damage your hearing. Now, losing something like 1-2% of your hearing isn't a bad trade for saving your own life and the lives of your loved ones, is it? Probably not, but if you can avoid it, it is a good thing. The loss is going to likely be less than that, but you get the idea.

A gunshot indoors results in you experiencing the sound/pressure multiple times versus firing outdoors. As such, you get several impacts. With the initial blast, you get the first report to your ears, say 150 db. That alone is enough to produce mechanical damage to the ear. The second event comes from the sound reflected off of the first wall and is a first even reflection. In fact, first reflections off the walls and floor (if no carpet) will still be quite powerful. In a typical hall or living room with a tile or wood floor, you can suffer 6 first reflective events with the first shot. If your shotgun is 150 db, your reflected events could each be well over 135 db and so all six reflected events will be enough damage your hearing. So your 1 shot has produced 7 damaging events to your ears and that is assuming you don't enough up with two or more impacting you at the same time and potentially doubling the pressure when they do. After that, the sound will bounce a few more times in quick succession such that you won't even know it. You will be hit be repeated events, all travels at the speed of sound and it will likely take place within less than a quarter of a second. The events will each be less and less as the sound/pressure dies off via travel distance (multiple reflections) and by being absorbed in things such as carpeting, furniture, etc.

22-mag noted...

Note: Each increase of 6 decibels doubles the noise level

This statement is in error or at least not helpful in regard to hearing protection. They may be referring to what is interpreted by the ear such that a 6db increase sounds twice as loud. HOWEVER As noted in the original post, the pressure doubles with each increase of 3 db. So a 6 db increase would actually be a quadrupling of the pressure and it is the pressure that causes the damage.