Earmuffs

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Earmuffs that are also hearing protection Peltor earmuffs.jpg
Earmuffs that are also hearing protection

Earmuffs refer to two different items. Both items consist of a thermoplastic or metal head-band that fits over the top or back of the head, and a cushion or cup at each end to usually cover both ears. The cups can either be clothing accessories designed to cover a person's ears for warmth or personal protective equipment designed to cover a person's ears for hearing protection.

Contents


Cold weather

Woman wearing cold-weather thermal earmuffs Cold-Weather Ear Muffs 2017.jpg
Woman wearing cold-weather thermal earmuffs

History

Thermal earmuffs were invented by Chester Greenwood of Farmington, Maine in 1873, when he was 15. [1] He reportedly conceived the idea while ice skating, and asked his grandmother to sew tufts of fur between loops of wire. [2] His patent was for improved ear protectors, which he and his local employees manufactured in the Farmington area for nearly 60 years. [1]

Earmuffs vs. hats

Two people wearing behind-the-neck earmuffs Elderly couple with ear muffs.jpg
Two people wearing behind-the-neck earmuffs

Thermal earmuffs are worn for protection from the cold. Because the ears extend from the sides of the head to gather sound waves, they have a high skin surface-area-to-volume ratio, and very little muscle tissue, causing them to be one of the first body parts to become uncomfortably cold as temperatures drop. Some people experience this discomfort even if most of the body is comfortably warm, especially during strenuous activity. Wind can often cause the ears to be much colder than the rest of the head. When the ears are uncomfortably cold and the rest of the body is much warmer, using a winter hat or the hood of a jacket to cover the ears may cause the head or body to be uncomfortably hot, possibly inducing perspiration of the head, a dangerous condition in cold weather. Earmuffs can be used to warm the ears only, avoiding overheating other parts of the body or trapping exhaust heat from strenuous movement.

Types of thermal earmuffs

There are two main types of thermal earmuffs. One type has a structure similar to large headphones, with a band going over the top of the head. Another type has two round earpieces made from a material that can produce heat, connected to a thick headband going around and behind the head. Some headbands are thick and wide enough to warm the ears, and are referred to "earmuffs" when used this way.

Hearing protection

A pair of Husqvarna acoustic earmuffs. Ear muff white bg.jpg
A pair of Husqvarna acoustic earmuffs.
A hard hat with attached face shield and ear defenders. Chainsaw helmet.jpg
A hard hat with attached face shield and ear defenders.

History

Acoustic earmuffs are believed to have originated during World War II. [3] Pilots of military aircraft wore leather flaps over their ears, supposedly to protect against noise-induced hearing loss due to engine noise. [3] Prototype versions of earmuffs, composed of a headband and cuffs to fit over the outer ear, were soon after developed. These early versions were not practical due to the discomfort caused by the headbands being tightly fixed against the head. [3] In 1954, an earmuff with a more comfortable cushion design was developed. [3]

Overview

Hearing protection in the workplace in the United States is regulated by organizations such as the Occupational Safety and Health Administration (OSHA), the Mine Safety and Health Administration (MSHA), and the National Institute for Occupational Safety and Health (NIOSH). Hearing protection can be included in hearing conservation programs if noise exceeds a certain criteria. OSHA recommends the use of hearing protection devices (HPD) when an employer is exposed to an average noise intensity of 85 dBA over an 8-hour shift. HPD is required when exposed to average noise intensity of 90 dBA or greater over an 8-hour shift. [4] MSHA requirements are similar to OSHA. OSHA and MSHA require the use of hearing protection for workers who have not had a baseline hearing test or have had a shift in hearing thresholds, called a standard threshold shift. [4] [5] But this does not mean that OSHA considers HPDs to be effective. [6]


Hearing protection earmuffs have cups lined with sound-deadening material, like thermal earmuffs and headphones in appearance, which are worn as hearing protection. These may be carried on a head-band or clipped onto the sides of a hard hat, for use on construction sites. Some manufacturers combine headphones with ear defenders, allowing the wearer to listen to music, communication, or other audio source and also enjoy protection or isolation from ambient noise. For extra sound attenuation, earplugs can also be used in conjunction with earmuffs. [7] The head-band and outer covering is usually made from a hard thermoplastic or metal. The protection usually comes from acoustic foam – this absorbs sound waves by increasing air resistance, thus reducing the amplitude of the waves. The energy is transformed into heat. Earmuffs can be used in the workplace or recreationally for loud activities, e.g., concerts, shooting firearms, heavy machinery, mowing, etc.

When persons are exposed to excessively loud environments (85 dB or more), hearing protection devices are recommended to prevent noise-induced hearing loss. [8] [9] Hearing protection should be worn whenever power tools, loud yard equipment, or firearms are used. Any noise greater than 140 dB can cause permanent hearing loss. Firearms range from a noise level of 140 dB to 175 dB depending on the firearm type. It is recommended to use dual hearing protection (earmuffs and earplugs together) when using firearms. [10] Exposure to loud noises damages the hair cells in the inner ear that are essential for sending neural impulses to the brain in order to perceive sounds. Loss of these hair cells leads to hearing loss that may cause speech and sounds to be muffled or distorted. Tinnitus is often associated with hearing loss; there is no cure for tinnitus. [11] In the workplace, OSHA requires the use of hearing protection devices whenever a person is exposed to an average noise intensity of 90 dBA or greater over an 8-hour shift. The louder the environment, the less time that a person may spend there without the risk of incurring hearing loss. NIOSH has also developed standards for hearing protection. [12] Compared to OSHA, the NIOSH standards are more conservative in their estimates for safe noise exposure times. Tabulated below are the NIOSH standards for the maximum daily exposure times at various noise levels. [13]

Level of noise (dB A)Maximum daily exposure time
858 hours
912 hours
9730 minutes
1037 minutes

Because the auditory system has varying sensitivity to sound as a function of frequency, unprotected noise exposures to mid- to high- frequency sounds pose greater risk to hearing than low frequency sounds. This frequency dependence is reflected in the use of the A-weighting curve to describe the decibel level of an exposure (dB A). [14] The A-weighting curve weights the mid frequency content, 500 to 4000 Hz, more than the frequencies outside that range. At lower, non-damaging sound levels, hearing protection will reduce fatigue from frequent exposure to sound.

Attenuation characteristics

The variability in the effectiveness of the earmuffs when used by 8 participants (REAT method) Shkarinov+Denisov.jpg
The variability in the effectiveness of the earmuffs when used by 8 participants (REAT method)

A typical earmuff attenuates (decreases) the level of noise by approximately 23 dB when tested under carefully controlled laboratory conditions. [16] The EPA requires that earmuff manufacturers test each device's performance and indicate their specific noise-reduction capabilities on the product labeling. [17] This single number is called the Noise Reduction Rating, or NRR. The attenuation is higher when measured in laboratory testing than worn in the field, or in real world settings. However, earmuffs had the least variability compared to earplugs. Discrepancies between the field and lab results could be due to improper training of how to wear the device. [18] Experiments have indicated that the actual attenuation achieved by ordinary users of earmuffs is only 33% to 74% of the labeled NRR. [18] Improper fit, device deterioration, and a poor seal with the head all contribute to reduced device performance. Despite these drawbacks, research has shown that the real-world performance of earmuffs is in closer agreement to manufacturers' labels than it is for earplugs. [18] This suggests that earmuffs are more intuitive for users to wear correctly and in some cases may be a more appropriate choice of hearing protection.

When deciding between earmuffs and earplugs, it is also important to consider the noise reduction levels achieved at different sound frequencies. In general, earmuffs provide less attenuation for low-frequency (<500 Hz) sounds than earplugs. [19] Thus, in situations where noise is dominated by low-frequency energy, earplugs are likely to be more effective. Earmuffs also fail to provide any noise reduction at infrasonic frequencies (< 20 Hz), [20] which is energy that cannot be heard because it falls below the range of human hearing sensitivity. In contrast, earplugs can provide some attenuation to infrasonic sounds. [20]

Passive vs. active

There are two different types of earmuffs used to protect the user from loud sounds based on the acoustical properties and materials used to create them: passively attenuating and actively attenuating earmuffs.

The ability of a passive earmuff to attenuate a signal is based on the materials used. The material and structure of the earmuff device is used to decrease the sound level that is transmitted through the ear canal. Materials, such as a cupped foam coated in hard plastic, will block sound due to the thick and dampening properties of the foam. [21]

Active earmuffs have an electronic component and microphones that allow the user to control their access to communication while attenuating background noise. When in loud, hazardous settings, the wearer may still be required to listen to outside sources, such as machinery work, their supervisor's commands, or talk to their colleagues. While the material and design of the muff allows for a reasonable attenuation (roughly 22 dB NRR), the user has the option to allow some sounds in that are necessary for their job. These earmuffs incorporate a volume control to increase and decrease the attenuation.

Active noise reduction earmuffs incorporate electronic noise cancellation or active noise cancellation to attenuate (roughly 26 dB NRR [21] ) low frequency noise. [22] A microphone, circuit, and speaker inside the muff are used to actively cancel out noise. As a signal enters the microphone, the electronics within the earmuff cast a signal back that is 180° out of phase with the signal, thus "cancelling" this signal. [23] This opposing signal reduces the amplitude of the waveform and reduces the signal. These earmuffs are designed to protect against a continuous signal, particularly low frequency sounds, such as diesel locomotives, heavy tractors, or airfields. [22]

Dual protection with earplugs

Most earmuffs can be expected to provide adequate attenuation for noise levels up to 103 dBC. [16] At levels beyond this intensity, it becomes necessary for users to wear earplugs with earmuffs on top in order to achieve adequate protection from hearing damage. The simultaneous use of two forms of hearing protections is known as dual hearing protection. The MSHA regulations stipulate that workers must use dual hearing protection when average 8-hour exposures are 105 dBA or greater. [17] The US Department of Defense recommends use of dual protection when exposed to noise ranging from 108-118 dBA. [24] Dual protection is also recommended when shooting firearms because of the extremely high-level impulses (140 dB and greater) produced. [25]

The amount of noise reduction from dual hearing protection is NOT a sum of the noise reductions ratings from the two devices. [26] For example, if wearing an earplug with a NRR of 25 dB and an earmuff with an NRR of 20 dB, the combined protection would not be 45 dB. Instead, 5 dB should be added to the higher of the two NRRs. [26] In the preceding example, the combined earmuff and earplug NRR would be estimated at 30 dB (25 dB plus 5).

Barriers to effectiveness

Fit

A proper fit of the earmuffs on the head is essential to providing adequate hearing protection. [27] [28] Individuals will require earmuffs of differing sizes. [29] This is especially important to remember when considering earmuffs for children. Muffs should make a good seal against the head and should fully cover the outer ear without pushing against the ears. Additionally, the headband should be the correct length to hold the cushions over the ears. [29] Otherwise, sound can leak under the muffs and will reach the users' ears. Some wearers may use their earmuffs when hair is covering their ears or while wearing glasses. Prior to placement on the head, hair should be carefully pulled back and away from the cushions. Placing earmuffs over obstructing hair or safety glasses with thick frames may reduce the earmuff attenuation by 5-10 dB. [30] Even eyeglasses with thinner frames can reduce the effectiveness of hearing protection by 3-7 dB. [29]

The size of the "standard" cup is 65x41 mm . During an anthropometric study, the ear sizes of 2436 pilots were obtained, the maximum dimensions: 79.7 and 53.8 mm (right image). NIOSH naushniki en.jpg
The size of the "standard" cup is 65×41 mm . During an anthropometric study, the ear sizes of 2436 pilots were obtained, the maximum dimensions: 79.7 and 53.8 mm (right image).

One simple method for checking earmuff fit is to lift one or both muffs away from the head while in a noisy environment. If the noise is considerably louder with the adjustment, then the earmuffs are providing at least some degree of noise reduction. [29]

Improper earmuff fit can cause discomfort, which in turn may cause the individual to avoid wearing the hearing protection device, reducing its effectiveness. Characteristics of a comfortable earmuff include: lightweight material, soft and removable circumaural cushions, low heat and humidity buildup, easy maintenance, reduction in low-frequency noise, no resonances of sound within the earcup, wide headband, and large enough earcups to allow for full coverage of the outer ear. If the individual finds the hearing protection device to be uncomfortable, he or she should explore other options for hearing protection, such as a different style of earmuff or earplugs. [33]

Styles

There are different earmuff style options for HPD users. Styles include: cap-mounts for hard hats, neckbands for use with welding helmets and faceshields, folding earmuffs are meant to be portable and easy to store, and multi-position earmuffs worn in varies positions are useful for versatility to wear both earmuffs and other safety ware, such as glasses or masks. [21]

Structural transmission

It is possible for sound to transmit through the earmuff materials, reducing the device's effectiveness. This transmission is primarily seen above 1000 Hz. [33]

Vibration of the earmuff

Exposure to high level noise (190 dB SPL) may cause the earmuff to vibrate off the external ear causing a leak which would allow hazardous exposure to dangerous levels of noise. [34] In loud enough environments, the ear canal can vibrate, causing the air trapped inside the earcup to vibrate as well. This typically only occurs with low frequency noise, but can reduce the effectiveness of the hearing protection device. [33] Technology in earmuffs is developing and shows promise in reducing the effects of airflow vibrations in the ear muffs. [21]

Readjustment

During the amount of time an individual wears earmuffs, the device can be jostled and displaced from the proper position that allows for the highest attenuation. This can be common in the workplace, as many individuals are in motion during the time they are wearing the hearing protection device. Moving the jaw while chewing or talking and perspiration are examples of ways in which readjustment can occur, causing the seal to be broken between the earcup and skin and allowing sound to leak in. [35]

Deterioration

It is also important to consider the age and physical condition of earmuffs. Earmuffs should be inspected regularly for cracks and changes in shape or firmness. Headbands may also lose their tension or ability to properly adjust to the head, which could lead to a decrease in device effectiveness. [35] Physical changes could create an opening to the ear, allowing sound through and reducing attenuation. According to some manufacturers, ear cushions should be replaced every 6-8 months if used regularly. If earmuffs are used very frequently then the cushion should be replaced every 3-4 months. [36]

Detriments

Wearing earmuffs makes it difficult to communicate because it blocks speech noise which may make speech sound muffled or unintelligible. It also makes it difficult to localize sound. [37]

Specific considerations for hearing protection for workers with hearing loss

Workers with hearing loss face additional risk factors on the job site such as an inability to hear warning signals or alarms, an increased difficulty to tell where sounds are coming from, and increased difficulty communicating with co-workers. [38] This occurs due to the hearing protection device (HPD) attenuating the signals/noises below the level that the worker is able to hear. [31] OSHA regulations require individuals to wear HPD regardless of their amount of hearing loss, even if they have a severe to profound hearing loss. [39] Workers that have sustained a standard threshold shift are required by OSHA to wear HPD at an 85 dB TWA. [34] There are special considerations to take into account when fitting HPD on workers with a hearing loss. These factors include comfort, degree and configuration of the worker's hearing loss, the necessary communication demands in the workplace (verbal vs. nonverbal), the ease of communication, and the noise exposure levels of the worker. [40]

Workers may want to wear their hearing aids under an earmuff. According to OSHA, hearing aids should not be used in areas with dangerous noise levels. However, OSHA allows for the professional(s) in charge of the hearing loss protection program to decide on a case-by-case basis if a worker can wear their hearing aids under an earmuff in high-level noise environments. Workers are not permitted to wear their hearing aids (even if they are turned off) instead of using HPD. OSHA specifies that hearing aids are not "hearing protectors" and do not attenuate enough sound to be used instead of HPD. [34] Wearing hearing aids alone, without the use of earmuffs, could potentially cause additional noise-induced hearing loss. It is recommended that workers should not use their hearing aids without the use of an earmuff when exposed to sound levels over 80 dBA. [41]

Devices that provide both communication enhancement and hearing protection can be used to attenuate loud sounds and amplify soft-level sounds. These are available with both wireless and wired options. [34] [40] The effects of these will vary based on the degree and configuration of the worker's hearing loss. Dual hearing protection with electronic/communication elements may aid a person with hearing loss in hearing warning signals and help with communication. Workers with a high frequency hearing loss may benefit more from HPD that attenuates sounds equally across the pitch range. This is helpful because traditional HPD will attenuate the higher frequencies (where these individuals have a hearing loss) more than the mid- and low-frequencies. Whereas, HPD that attenuate equally across the pitch range, can provide more comfort and balancing of loudness across the pitches for these individuals with hearing loss. This type of HPD are commonly referred to as "musicians plugs." [40] NIOSH provides a "Hearing Protector Device Compendium" with information on the different types of HPD. [42]

See also

Related Research Articles

<span class="mw-page-title-main">Noise</span> Unwanted sound

Noise is sound, chiefly unwanted, unintentional, or harmful sound considered unpleasant, loud, or disruptive to mental or hearing faculties. From a physics standpoint, there is no distinction between noise and desired sound, as both are vibrations through a medium, such as air or water. The difference arises when the brain receives and perceives a sound.

<span class="mw-page-title-main">Hearing loss</span> Partial or total inability to hear

Hearing loss is a partial or total inability to hear. Hearing loss may be present at birth or acquired at any time afterwards. Hearing loss may occur in one or both ears. In children, hearing problems can affect the ability to acquire spoken language, and in adults it can create difficulties with social interaction and at work. Hearing loss can be temporary or permanent. Hearing loss related to age usually affects both ears and is due to cochlear hair cell loss. In some people, particularly older people, hearing loss can result in loneliness.

<span class="mw-page-title-main">Headphones</span> Device placed near the ears that plays sound

Headphones are a pair of small loudspeaker drivers worn on or around the head over a user's ears. They are electroacoustic transducers, which convert an electrical signal to a corresponding sound. Headphones let a single user listen to an audio source privately, in contrast to a loudspeaker, which emits sound into the open air for anyone nearby to hear. Headphones are also known as earphones or, colloquially, cans. Circumaural and supra-aural headphones use a band over the top of the head to hold the drivers in place. Another type, known as earbuds or earpieces, consists of individual units that plug into the user's ear canal. A third type are bone conduction headphones, which typically wrap around the back of the head and rest in front of the ear canal, leaving the ear canal open. In the context of telecommunication, a headset is a combination of a headphone and microphone.

<span class="mw-page-title-main">Noise-cancelling headphones</span> Headphones with active noise control

Noise-cancelling headphones are headphones that suppress unwanted ambient sounds using active noise control (ANC).

Occupational noise is the amount of acoustic energy received by an employee's auditory system when they are working in the industry. Occupational noise, or industrial noise, is often a term used in occupational safety and health, as sustained exposure can cause permanent hearing damage. Occupational noise is considered an occupational hazard traditionally linked to loud industries such as ship-building, mining, railroad work, welding, and construction, but can be present in any workplace where hazardous noise is present.

The permissible exposure limit is a legal limit in the United States for exposure of an employee to a chemical substance or physical agent such as high level noise. Permissible exposure limits were established by the Occupational Safety and Health Administration (OSHA). Most of OSHA's PELs were issued shortly after adoption of the Occupational Safety and Health (OSH) Act in 1970.

<span class="mw-page-title-main">Earplug</span> Device to protect ears from loud noises

An earplug is a device that is inserted in the ear canal to protect the user's ears from loud noises, intrusion of water, foreign bodies, dust or excessive wind. Since they reduce the sound volume, earplugs may prevent hearing loss and tinnitus, in some cases.

<span class="mw-page-title-main">Noise control</span> Strategies to reduce noise pollution or its impact

Noise control or noise mitigation is a set of strategies to reduce noise pollution or to reduce the impact of that noise, whether outdoors or indoors.

<span class="mw-page-title-main">Sound level meter</span> Device for acoustic measurements

A sound level meter is used for acoustic measurements. It is commonly a hand-held instrument with a microphone. The best type of microphone for sound level meters is the condenser microphone, which combines precision with stability and reliability. The diaphragm of the microphone responds to changes in air pressure caused by sound waves. That is why the instrument is sometimes referred to as a sound pressure level meter (SPL). This movement of the diaphragm, i.e. the sound pressure, is converted into an electrical signal. While describing sound in terms of sound pressure, a logarithmic conversion is usually applied and the sound pressure level is stated instead, in decibels (dB), with 0 dB SPL equal to 20 micropascals.

<span class="mw-page-title-main">Health effects from noise</span> Health consequences of exposure to elevated sound levels

Noise health effects are the physical and psychological health consequences of regular exposure to consistent elevated sound levels. Noise from traffic, in particular, is considered by the World Health Organization to be one of the worst environmental stressors for humans, second only to air pollution. Elevated workplace or environmental noise can cause hearing impairment, tinnitus, hypertension, ischemic heart disease, annoyance, and sleep disturbance. Changes in the immune system and birth defects have been also attributed to noise exposure.

<span class="mw-page-title-main">Noise-induced hearing loss</span> Medical condition

Noise-induced hearing loss (NIHL) is a hearing impairment resulting from exposure to loud sound. People may have a loss of perception of a narrow range of frequencies or impaired perception of sound including sensitivity to sound or ringing in the ears. When exposure to hazards such as noise occur at work and is associated with hearing loss, it is referred to as occupational hearing loss.

<span class="mw-page-title-main">Hearing conservation program</span>

Hearing conservation programs are designed to prevent hearing loss due to noise. Hearing conservation programs require knowledge about risk factors such as noise and ototoxicity, hearing, hearing loss, protective measures to prevent hearing loss at home, in school, at work, in the military and, and at social/recreational events, and legislative requirements. Regarding occupational exposures to noise, a hearing conservation program is required by the Occupational Safety and Health Administration (OSHA) "whenever employee noise exposures equal or exceed an 8-hour time-weighted average sound level (TWA) of 85 decibels (dB) measured on the A scale or, equivalently, a dose of fifty percent." This 8-hour time-weighted average is known as an exposure action value. While the Mine Safety and Health Administration (MSHA) also requires a hearing conservation program, MSHA does not require a written hearing conservation program. MSHA's hearing conservation program requirement can be found in 30 CFR § 62.150, and is very similar to the OSHA hearing conservation program requirements. Therefore, only the OSHA standard 29 CFR 1910.95 will be discussed in detail.

An Exposure Action Value (EAV) or Action Value (AV) is a limit set on occupational exposure to noise where, when those values are exceeded, employers must take steps to monitor the exposure levels. These levels are measured in decibels. The American Occupational Safety and Health Administration (OSHA) set the EAV to 85 dB(A). When the eight-hour time-weighted average (TWA) reaches 85 dB(A), employers are required to administer a continuing, effective hearing conservation program. The program consists of monitoring, employee notification, observation, an audiometric testing program, hearing protectors, training programs, and record-keeping requirements.

<span class="mw-page-title-main">Safe-in-Sound Award</span>

The Safe-in-Sound Excellence in Hearing Loss Prevention Award is an occupational health and safety award that was established in 2007 through a partnership between the National Institute for Occupational Safety and Health (NIOSH) and the National Hearing Conservation Association (NHCA). In 2018, the partnership was extended to include the Council for Accreditation in Occupational Hearing Conservation (CAOHC).

<span class="mw-page-title-main">Occupational hearing loss</span> Form of hearing loss

Occupational hearing loss (OHL) is hearing loss that occurs as a result of occupational hazards, such as excessive noise and ototoxic chemicals. Noise is a common workplace hazard, and recognized as the risk factor for noise-induced hearing loss and tinnitus but it is not the only risk factor that can result in a work-related hearing loss. Also, noise-induced hearing loss can result from exposures that are not restricted to the occupational setting.

Acoustic trauma is the sustainment of an injury to the eardrum as a result of a very loud noise. Its scope usually covers loud noises with a short duration, such as an explosion, gunshot or a burst of loud shouting. Quieter sounds that are concentrated in a narrow frequency may also cause damage to specific frequency receptors. The range of severity can vary from pain to hearing loss.

<span class="mw-page-title-main">Hearing protection device</span> Protection device for auditory organs

A hearing protection device, also known as a HPD, is an ear protection device worn in or over the ears while exposed to hazardous noise and provide hearing protection to help prevent noise-induced hearing loss. HPDs reduce the level of the noise entering the ear. HPDs can also protect against other effects of noise exposure such as tinnitus and hyperacusis. There are many different types of HPDs available for use, including earmuffs, earplugs, electronic hearing protection devices, and semi-insert devices.

The Auditory Hazard Assessment Algorithm for Humans (AHAAH) is a mathematical model of the human auditory system that calculates the risk to human hearing caused by exposure to impulse sounds, such as gunfire and airbag deployment. It was developed by the U.S. Army Research Laboratory (ARL) to assess the effectiveness of hearing protection devices and aid the design of machinery and weapons to make them safer for the user.

<span class="mw-page-title-main">Hearing protection fit-testing</span> Test for determining the effectiveness hearing protection devices

Hearing protector fit-testing is a method that measures the degree of noise reduction obtained from an individual wearing a particular hearing protection device (HPD) - for example, a noise canceling earplug or earmuff. Fit testing is necessary due to the fact that noise attenuation varies across individuals. It is important to note that attenuation can sometimes score as zero due to anatomical differences and inadequate training, as to the proper wear and use. Labeled HPD attenuation values are average values that cannot predict noise attenuation for an individual; in addition, they are based on laboratory measurements which may overestimate the noise reduction obtained in the real world.

<span class="mw-page-title-main">Safe listening</span> Avoiding hearing damage from intentionally heard sounds

Safe listening is a framework for health promotion actions to ensure that sound-related recreational activities do not pose a risk to hearing.

References

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  14. ↑ A-weighting
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  17. 1 2 Rawool, Vishakha (2012). Hearing Conservation. New York, NY: Thieme. ISBN   978-1-60406-256-4.
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  19. ↑ Berger, Elliot (1996b). The performance of hearing protectors in Industrial Noise Environments. EARlog 4. Aearo Company: Indianapolis, IN.
  20. 1 2 Berger, Elliot (1984). Protection for Infrasonic and Ultrasonic Noise Exposure. EARlog 14. Aearo Company: Indianapolis, IN.
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  24. ↑ U.S. Department of Defense (March 5, 2004). "Hearing Conservation Program".Instruction 6055.12.
  25. ↑ "Recreational Firearm Noise Exposure". www.asha.org. Retrieved 2017-02-24.
  26. 1 2 Berger, Elliot (1984). Attenuation of earplugs worn in combination with earmuffs. EARlog 13. Aearo Company: Indianapolis, IN.
  27. ↑ Voix, Jérémie; Smith, Pegeen; Berger, Elliott H (2018). "Chapter 12: Field Fit-Testing and Attenuation-Estimation Procedures". In D.K. Meinke; E.H. Berger; R. Neitzel; D.P. Driscoll; K. Bright (eds.). The Noise Manual (6th ed.). Falls Church, Virginia: American Industrial Hygiene Association. pp. 309–329. Retrieved 10 August 2022.
  28. ↑ Technical Committee CEN/TC 159 “Hearing protectors” (17 November 2021). EN 17479-2021. Hearing protectors - Guidance on selection of individual fit testing methods. Brussels: European Committee for Standardization. p. 46. ISBN   978-0-539-04746-2.{{cite book}}: CS1 maint: numeric names: authors list (link) link
  29. 1 2 3 4 Berger, Elliot (1988). Tips for fitting hearing protectors. EARlog 19. Aearo Company: Indianapolis, IN.
  30. ↑ Witt, Brad (2009). "Bad Assumptions About Hearing Protection" (PDF). Howard Leight. Sperian Hearing Conservation, LLC. Retrieved October 27, 2016.
  31. 1 2 Berger, Elliott H.; Voix, Jérémie (2018). "Chapter 11: Hearing Protection Devices". In D.K. Meinke; E.H. Berger; R. Neitzel; D.P. Driscoll; K. Bright (eds.). The Noise Manual (6th ed.). Falls Church, Virginia: American Industrial Hygiene Association. pp. 255–308. Retrieved 10 August 2022.
  32. ↑ Milton Alexander, Lloyd L. Laubach (1968). Anthropometry of the human ear. A photogrammetric study of USAF flight personnel. Wright-Patterson Air Forse Base, Ohio: Aerospace Medical Research Laboratories. p. 38.
  33. 1 2 3 Vishakha, Rawool (2011). Hearing Conservation: In Occupational, Recreational, Educational, and Home Settings. New York, NY: Thieme Medical Publishers, Inc. pp. 156–158.
  34. 1 2 3 4 Rawool, Vishakha Waman (2012). Hearing Conservation in Occupational, Recreational, Educational, and Home Settings. New York, NY: Thieme Medical Publishers, Inc. pp. 146–148.
  35. 1 2 Berger, Elliot (1996a). Hearing protector performance: how they work-and- what goes wrong in the real world. EARlog 5. Aearo Company: Indianapolis, IN.
  36. ↑ Leight, Howard. "Howard Leight | Hearing Protection and Hearing Conservation" (PDF). Howard Leight. Retrieved 2022-11-02.
  37. ↑ National Institute on Deafness and Other Communication Disorders. (2008). NIDCD fact sheet: Noise-induced hearing loss. Retrieved March 16, 2018 from http://www.wba.aplusanywhere.com/R85Content/media/video/health_as3/swfs/health_31_hearing_loss.pdf
  38. ↑ "Innovative Workplace Safety Accommodations for Hearing-Impaired Workers".
  39. ↑ "OSHA Regulations (Standards - 29 CFR)".
  40. 1 2 3 Berger, Elliott (2000). The Noise Manual, Fifth Edition. Fairfax, VA: AIHA.
  41. ↑ Berger, Elliot (1996). Can Hearing Aids Provide Hearing Protection. Indianapolis, IN: Aearo Company.
  42. ↑ "Hearing Protector Device Compendium". Centers for Disease Control and Prevention.
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