Standards hearing protection in the countries of the world correspond to different state standard specifications (in the Russian Federation it is 12.4.275-2014) and use different indicators to classify the acoustic effectiveness of protective products. In the article below, as the main indicator is used NRR (developed in the USA and recognized in Europe), since it is most common for hearing protection, designed to work with firearm.
Noise reduction ratio (NRR) Is the unit of measure used to determine efficiency. hearing protection in reducing the volume of sound. Ear protection, classified by their ability to reduce noise in decibels (dB), must be tested and approved by state sanitary control authorities. The higher NRR assigned to these agents, the greater the reduction in noise.
Basic theoretical questions
how NRR changes the impact of noise?
When ear protection are worn (and in accordance with the appropriate instructions), the level of exposure is calculated depending on the protection factor given by these means. Consider, however, that although NRR specified in decibels, the noise level is not reduced by the exact value assigned hearing protection. For example, if you are at a concert where the sound level is 100 dB, and you put earplugs with the coefficient NRR, equal to 33, the sound level for you will not fall to 67 dB. To determine the actual effect, you subtract from NRR seven and divide the difference by two. In our example, your noise protection will be (33-7) / 2 = 13. This means that at a concert with a sound level of 100 dB your earplugs with NRR= 33 will reduce the noise level to a value of 87 dB.
How does NRR remedies?
When ear protection are used together (i.e., earplugs and headphones at the same time) instead of adding their values NRR, you add five units to a higher value. For example, earplugs with NRR 29 with headphones with NRR 27 collectively provide NRR 34 dB.
What is considered excessive noise?
Although the exact sound level can be measured by a variety of instruments, excessive noise generally considered to be an impact of 85 or more decibels over an 8-hour period. However, if the noise level is 100 dB for two hours, wearing hearing protection also required. In all cases when the noise level exceeds the specified values, hearing protection is required.
Acceptable exposure levels
The most common sources of noise, the level of which is considered dangerous: tillers, rock concerts, firearms, fireworks, motorcycles, tractors, power tools and industrial installations. Using hearing protection It is strongly recommended for long-term exposure to these sources, all of which are capable of producing noise in excess of 90 dB.
150 dB – rock concert at the peak
140 dB – weapons, alarm sirens, jet engines
130 dB – jackhammer
120 dB – takeoff jet aircraft, the rehearsal of the ensemble
110 dB – machines, model airplanes
100 dB – snowmobile, chainsaw, puncher
90 dB – walk-behind tractor, power tool, road noise, subway
80 dB – alarm, busy street
70 dB – vacuum cleaner
60 dB – talk, household appliances
50 dB – heavy rain
40 dB – quiet room
30 dB – whisper library
Basic hearing protection
Handy tools – pistol cartridges
Among experienced shooters, especially with service past, such ersatz in the course. Unfortunately, cartridges instead of earplugs have more disadvantages than advantages. They are not hygienic, and can easily lead to allergies. In the ear, they are not stable, in static shooting they still hold, and when moving, their loss is only a matter of time. Their highly questionable effectiveness depends on the size of the ear canal. Actually, the level of sound reduction is not measured by anyone.
Strongly not recommended for use.
The oldest form of ear plugs available at any pharmacy. Made from cotton stripe impregnated with a mixture of wax, paraffin and vaseline. Hermetically sealed in foil, in the form of strips, and similar to chewing gum. Obviously, they do not have the specified sizes for the size of the ear.
To use these earplugs, you need to tear off the corresponding piece of packaging. And the only one, the manufacturer does not recommend adding pieces, as they can separate and get stuck in the ear canal. Then, warming up in the hands, roll up the plug, which you then insert into the ear.
Magnitude NRR they have a value of 26 dB. They really work and protect your hearing, muffling all sounds – including speech, naturally. Theoretically, they can be used many times until they become dirty. In practice, they become dirty after the first departure to the shooting range, and even more so – who will bother with storing a slippery piece that costs a penny?
Their lack is connected with their temperature sensitivity – in the cold they become hard and uncomfortable.
Can serve as a backup option, in extreme cases.
Foam Polymer Ear Plugs
Probably the most popular ear protection. They are made of foamed polyurethane with the addition of an elastomer, they can be found almost everywhere in a great variety of colors. When used, they are squeezed with fingers and then inserted into the ear canal. After the introduction, you need to wait a few seconds until they finish off, blocking the channel, and after that they are ready to work. Their NRR is 28-44 dB.
In general, they are reusable, and if soiled, they can be washed with soap and allowed to dry. Not strongly influenced by low temperatures. Often used with headphones to enhance performance.
Great, cheap and effective hearing protection.
There is a variation of them, a design in which both plugs are attached to the handle. No more than a marketing ploy to sell you a plastmassk curve to a load of earplugs.
Silicone ear plugs
Really reusable earplugs for shooting. The shape of the side usually resembles a coniferous tree with two or four tiers of “branches”. They are sold in separate pairs connected by a thread, and sometimes even on a safety retractor. Their indicator NRR ranges from 22-29 dB.
They are very practical and convenient in care, enough water and soap. Theoretically, they are dimensionless, but made in different sizes (usually three – small, medium and large) provide more convenience and muffle noise better. Almost not sensitive to temperature changes.
Interestingly, they are also used in water sports – they prevent water from entering the ear.
Semi-Active Ear Plugs
Step into the future compared to conventional silicone plugs, but created without the use of any electronics. Their ability to skip the selected frequency range is due to the laws of physics. A sound of small intensity passes through the channel located inside them, at the frequency of human speech, the other noises are cut off. By turning the filter plug, these earplugs turn into an analogue of the above-described conventional silicone plugs.
They are reusable, their NRR is 23-25 dB with a closed filter, with the same open – about 7-8. The manufacturer usually recommends shooting with an open filter and overlapping it in places with dense continuous noise (for example, loading into a transport aircraft).
A very interesting solution with broad functionality, bringing them closer to the active hearing protection. Their disadvantage is that an open cap leads to a small, but still lowered level of protection.
Common and widespread hearing protection, cheap, quite comfortable, does not require acrobatics when installed in the ear. Some shooting headphones even fold in the headband for easy transportation. The level of muting is about 20-30 dB, depending on the size of the cup and the size of the ears of the wearer.
If you do not want to stuff something into your own ear, and you don’t have enough money for active headphones, this is the solution for you.
Their disadvantage is the same, common to all passive systems – the inability to hear the surrounding sounds with the means of protection put on. And also the fact that the ears under them are often hot.
Passive (and semi-active) shooting headphones and earplugs for shooting have another drawback – the inability to connect to radio stations. Sometimes being connected is even more important than hearing surrounding sounds. In this case, an intermediate solution can come to the rescue – ordinary earplugs for the music player,
with passive headphones worn over them.
Active headphones and earplugs solve both the problem of perception of ambient sounds, and the problem of combining with communication devices. They are equipped with external microphones, the sounds from which are fed into the electronic circuit, are muted or cut off, and then are output to the built-in speakers inside the earphone, and from there right into the ear of the wearer. The power supply is provided by small batteries – AAA, AA or CR123. In these headphones, you can talk to people and not be afraid of hearing damage by loud sounds produced nearby – for example, by shooting. Some models of active hearing protection have a connector for connecting radio equipment, including mobile phones.
At first glance, they look like ordinary passive ones, with additional features in the form of microphones and controls. Possess NRR at 25 dB. Usually equipped with a headband, passing from above, but under the helmet it is more convenient to wear options with an occipital headband. A number of models can be fixed directly on the helmet through the adapter, and not only tactical headphones, but also industrial construction.
Some headphones have the ability to connect a microphone to them – on the bar or laryngo. To connect the resulting headset with a radio station, you need a PTT node, a “button” – an intermediary between the headset and the radio station. This device is in itself a topic for a separate article; we will not dwell on it here in detail.
Their disadvantages – more noticeable weight, significant price. They are sometimes too warm. They may interfere with the safety helmet, especially without cutouts above the ears.
Active ear plugs
Perhaps the most technologically advanced variety hearing protection, taking into account the compactness of the electronic circuits responsible for sound processing. Active earplugs, with some exceptions, consist of ear inserts with an integrated microphone, a speaker, a cut-off sound insert, and a control circuit with a power source. Some exceptions have electronics placed in each plug (in fact, electronic circuits are duplicated).
The main goal of the manufacturer in this case is to get rid of the headband and ear cushions, which in many cases are inconvenient. This is important, especially if the wearer wears a hard hat — and in the case of earplugs, the shape of the helmet does not matter, as they fit under any. Due to the exclusion of the heaviest elements of the structure, the user no longer loads the head, which is also important.
The plug itself is usually made of foamed polymer and provided with a sound-transmitting channel. The noise protection level is usually around 30-35 dB.
In the case of communication headsets, earplugs are also equipped with an internal microphone that receives the sound of the wearer’s voice from the ear canal. Thus, there is no need to use an external microphone, although some samples allow this as one of the use cases. Civilian versions are different in this – they work with mobile phones, and their microphone is placed on a cord with earplugs, just like ordinary headsets for cell phones. Outside, there is also a receive / reset button, which, if the music player is connected, becomes the start / pause button.
The electronic sound processing unit and all buttons are located on the remote unit, usually including the battery compartment. The largest of them are smaller than a pack of cigarettes, and the smallest – with a box of matches. Some earplugs have a built-in battery that charges in the transport case. Some earplugs are made splashproof, and most are completely waterproof.
The disadvantage of them, in general, is one – some people do not like to shove something into their ears. Well, the price, of course.
Safety Instructions: Hearing protection when shooting