Ear muffs

Chester Greenwood invented ear muffs in 1873 when he was 15 years old ^{[1] [2]} . The idea came up while ice skating. Its implementation was helped by his grandmother, who sewed fur linings and attached them to a wire headband ^[3] . On March 13, 1877, patent # 188,292 was received for the invention. Greenwood has been manufacturing ear protection products for 60 years ^{[1] [4]} .

There are two types of modern protective headphones - warmed and anti-noise:

• Insulated headphones - used in cold weather to keep your ears warm.
• Anti-noise headphones - used to protect your ears from noise. They can be used both separately and together with a protective helmet or helmet. There are two types of anti-noise headphones - passive and active:
  • Passive headphones protect hearing by reducing the audible sound (the noise becomes quieter, as well as any other sounds - speech, warning signals, etc.).
  • Active headphones have built-in microphones and speakers, which allows you to simultaneously reduce the effects of noise, hear the environment and communicate comfortably. In some models it is possible to connect walkie-talkies, telephones and other external devices. For additional hearing protection, a combination of active headphones and anti-noise inserts can be used, this allows you to increase hearing protection, while maintaining the possibility of comfortable communication and audibility of the environment ^[5] .
  • Ballistic headphones are an intermediate variant designed specifically to protect hearing organs from barotrauma during firing from various small arms and artillery weapons, rocket launches, explosive explosives, etc. They can be either passive (for the most part) or active. In 1962, the US Army Medical Service developed TTSR ballistic headphones built into the tank helmet (headset) to protect the hearing organs of crew members at the time of the shot from the tank gun, which, when connected to the tank’s circuitry a millisecond before the shot, generated a click of such a tonality that it was unconsciously muscles of the auricle and middle ear reacted reflexively , due to a click, they contracted in such a way as to prevent the rupture of the eardrum from the too loud sound of a shot ^[6] .

The headband and outer cover are usually made of thermoplastic or metal. The cups are filled with acoustic foam that absorbs sound waves.

If people are exposed to loud noises (for example, working with power tools, engines, firearms), then hearing protection must be used to prevent hearing loss.

European noise regulations:

During certification, personal protective equipment for hearing organs is tested, and certain requirements are set for their effectiveness, which are contained in the relevant standards. But the use of PPE in real production conditions differs from laboratory tests. As a result, the effect of the use of PPE of the hearing organs in practice is much weaker than that indicated in advertising catalogs (where laboratory values ​​are given). According to experts, the real effectiveness of PPE of the hearing organs is lower than the laboratory one at least 2 times (by 10-15 dB or more) ^{[7] [8]} . Since the measurement of noise attenuation in the laboratory for certification of PPE is carried out with frequency correction C, American experts recommend that to assess the expected attenuation of noise when using PPE of the hearing organ, first obtain its relative attenuation coefficient NRR with correction on a scale of A, subtracting from NRR 7 dB, and then divide the result in half to take into account that the values ​​obtained in the laboratory are rarely achieved in practice ^[9] . The obtained value of the noise attenuation coefficient can be subtracted from the measured noise level to assess whether this protective equipment is capable of reducing to an acceptable value ( For example, with NRR = 37 dB and a noise level of 105 dB we get: 105 - ([37-7] / 2 ) = 105 - 15 = 90 dB - the efficiency is insufficient ). It is also important to train employees in the proper use of PPE for the hearing organs ^[10] . PPE of the hearing organ is the last and most unreliable means of protection , and its use is permissible only when technical ^{[11] [12] [13] [14] [15] [16]} and organizational measures have not allowed to reduce the noise level to an acceptable value. The use of PPE of the hearing organ should be accompanied by periodic medical examinations to monitor the real effectiveness of their use ^[17] .

In general, to effectively protect workers from noise, PPE should be selected and applied as part of a hearing preservation program . The opinion of Western scientists about the undesirability of using PPE of the hearing organ to protect against noise due to their unreliability is shared by Soviet and Russian specialists in occupational diseases ^[18] .

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  Headphones with active noise reduction - using microphones on the outer surface, they receive noise information and generate noise under the “cups” to suppress loud noise.

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  Headphones with active noise reduction - using microphones on the outer surface, they receive noise information and generate noise under the “cups” to suppress loud noise. Mounted on a helmet.

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  Headphones with active noise reduction - using microphones on the outer surface, they receive noise information and generate noise under the “cups” to suppress loud noise. To facilitate communication, there is radio communication.

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  Headphones with active noise reduction - using microphones on the outer surface, they receive noise information and generate noise under the “cups” to suppress loud noise. To facilitate communication, there is radio communication.

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  Personal protective equipment for the hearing organ. Headphones with active noise reduction - using microphones on the outer surface, they receive noise information and generate noise under the “cups” to suppress loud noise. To facilitate communication, there is radio communication.

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  Headphones with active noise reduction - using microphones on the outer surface, they receive noise information and generate noise under the “cups” to suppress loud noise.

• Ear plugs
• Hearing impairment
• Headphones
• Personal protective equipment
• Hearing preservation program
• Industrial noise
• Hearing Protective Equipment - Chapter 6 of the NIOSH Noise Protection Guidelines

• National Institute of Occupational Safety and Health - Hearing Protection Catalog
• GOST R EN 13819-2-2011 - Occupational safety standards system. Personal protective equipment for the hearing organ. Acoustic Test Methods
• GOST R 12.4.208-99 - Occupational safety standards system. Personal protective equipment for the hearing organ. Headphones. General technical requirements. Test methods
• GOST R 12.4.210-99 - Occupational safety standards system. Personal protective equipment for the hearing organ. Antinoise earphones mounted with a protective helmet. General technical requirements. Test methods
• GOST R 12.4.211-99 - Occupational safety standards system. Personal protective equipment for the hearing organ. Antinoise. Subjective method for measuring noise absorption