Occupational noise

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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.

Contents

Regulation

In the US, the National Institute for Occupational Safety and Health (NIOSH) and the Occupational Safety and Health Administration (OSHA) work together to provide standards and regulations for noise in the workplace. [1]

National Institute for Occupational Safety and Health (NIOSH), Occupational Safety and Health Administration (OSHA), Mine Safety and Health Administration (MSHA), Federal Railroad Administration (FRA) have all set standards on hazardous occupational noise in their respective industries. Each industry is different, as workers' tasks and equipment differ, but most regulations agree that noise becomes hazardous when it exceeds 85 decibels, for an 8-hour time exposure (typical work shift). This relationship between allotted noise level and exposure time is known as an exposure action value (EAV) or permissible exposure limit (PEL). The EAV or PEL can be seen as equations which manipulate the allotted exposure time according to the intensity of the industrial noise. This equation works as an inverse, exponential, relationship. As the industrial noise intensity increases, the allotted exposure time, to still remain safe, decreases. Thus, a worker exposed to a noise level of 100 decibels for 15 minutes would be at the same risk level as a worker exposed to 85 decibels for 8 hours. [2] Using this mathematical relationship, an employer can calculate whether or not their employees are being overexposed to noise. When it is suspected that an employee will reach or exceed the PEL, a monitoring program for that employee should be implemented by the employer. [3]

The above calculations of PEL and EAV are based on measurements taken to determine the intensity of that particular industrial noise. A-weighted measurements are commonly used to determine noise levels that can cause harm to the human ear. There are also special exposure meters available that integrate noise over a period of time to give an Leq value (equivalent sound pressure level), defined by standards.

Regulations in different countries

Permissible noise levels in different countries [4]
CountryTWA, dBA

(for an 8-hour shift)

Level increase corresponding to doubling the dose

(Exchange rate)

Argentina903
Australia853
Brazil855
Canada85 & 82 [5] 3
Chile855
China70-903
European Union countries853
Finland853
France853
Germany85, 70, 55 [6] 3
Hungary853
India90–
Israel855
Italy853
Netherlands803
New Zealand853
Norway85, 55, 703
RF [7] 803
Spain853
Sweden853
United Kingdom853
USA90 (100 [8] )*5
Uruguay903
* OSHA issued a directive to inspectors in 1983. [9] They are ordered to stop requiring employers to install engineering noise control if noise dose < 100 dBA. This decision is considered illegal, [10] but it is carried out in practice in most US states. [11]

These numerical values do not fully reflect the real situation. For example, the OSHA standard [3] sets the Action Level 85 dBA, and the PEL 90 dBA. But in practice, the Compliance Safety and Health Officer must record the excess of these values with a margin, in order to take into account the potential measurement error. And, instead of PEL 90 dBA, it turns out 92 dBA, and instead of AL 85 dBA, it's 87 dBA. [12]

Risks of occupational hearing loss

Temporary hearing loss after loud noise exposure. If such exposure is long enough, this temporary threshold shift may become permanent. Temporary threshold shift (hearing loss) after noise exposure.jpg
Temporary hearing loss after loud noise exposure. If such exposure is long enough, this temporary threshold shift may become permanent.

Occupational noise, if experienced repeatedly, at high intensity, for an extended period of time, can cause noise-induced hearing loss (NIHL) [14] which is then classified as occupational hearing loss. Most often, this is a type of sensorineural hearing loss. [15]

Noise, in the context of industrial noise, is hazardous to a person's hearing because of its loud intensity through repeated long-term exposure. In order for noise to cause hearing impairment for the worker, the noise has to be close enough, loud enough, and sustained long enough to damage the hair cells in the auditory system. These factors have been taken into account by the governing occupational health and safety organization to determine the unsafe noise exposure levels and durations for their respective industries.

Noise can also affect the safety of the employee and others. Noise can be a causal factor in work accidents as it may mask hazards and warning signals and impede concentration. High intensity noise interferes with vital workplace communication which increases the chance of accidents and decreases productivity. [16]

Noise may also act synergistically with other hazards to increase the risk of harm to workers. In particular, toxic materials (e.g., some solvents, metals, asphyxiants and pesticides) have some ototoxic properties that may affect hearing function.

Modern thinking in occupational safety and health further identifies noise as hazardous to workers' safety and health. This hazard is experienced in various places of employment and through a variety of sources.

Reduction

Hierarchy of Controls guideline NIOSH's "Hierarchy of Controls infographic" as SVG.svg
Hierarchy of Controls guideline

There are several ways to limit exposure to hazardous occupational noise. The hierarchy of controls [17] is a guideline for reducing hazardous noise. Before starting a noise reduction program, base noise levels should first be recorded. [18] After this the company can start to eliminate the noise source. If the noise source cannot be eliminated, the company must try to reduce the noise with alternative methods. This process is called Acoustic quieting.

Acoustic quieting is the process of making machinery quieter by damping vibrations to prevent them from reaching the observer. The company can isolate the certain piece of machinery by placing materials on the machine or in between the machine and the worker to decreases the signal intensity that reaches the worker's ear.

If elimination and substitution are not sufficient in reducing the noise exposure, engineering controls should be put in place by the employer. [lower-alpha 1] An engineering control usually changes the physical environment of a workplace. For noise reduction, an engineering control might be as simple as putting barriers in-between the noise source and the employee in order to disrupt the transmission path. An engineering control might also involve changing the machine that produces the noise. Ideally, most machines should be made with noise reduction in mind, but this doesn't always happen. Changing the machinery involved in an industrial process may not be possible, but is a good way to reduce the noise at its source. [33]

Banded ear plugs Bouchon arceau.jpg
Banded ear plugs

To decrease an employee's exposure to hazardous noise, the company can also take administrative control by limiting the employee's exposure time. This can be done by changing work shifts and switching employees out from the noise exposure area. An employer might also implement a training program so that employees can learn about the hazards of occupational noise. Other administrative controls might include restricting access to noisy areas as well as placing warning signs around those same areas.

If all other controls fail to decrease the occupational noise exposure to an acceptable level, hearing protection should be used. [34] There are several types of earplugs that can be used to attenuate the noise to a safe level. Some earplug types include: single-use earplugs, multiple-use ear plugs, and banded ear plugs. [35] Depending on the type of work being done and the needs of the employees, earmuffs might also be a good option. While earmuffs might not have as high of a noise reduction rating (NNR) as earplugs, they can be useful if the noise exposure isn't very high, or if an employee cannot wear earplugs. Unfortunately, the ability of HPDs decrease the risk of health damage is close to zero in practice. [9] [36]

Initiatives

Since the hazards of occupational noise exposure were realized, programs and initiatives such as the US Buy Quiet program have been set up to regulate or discourage noise exposure. The Buy Quiet initiative promotes the purchase of quieter tools and equipment and encourages manufacturers to design quieter machines. [37] Additionally, the Safe-In-Sound Award was created to recognize successes in hearing loss prevention programs or initiatives. [38]

See also

General:

Notes

Related Research Articles

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

Noise is unwanted or harmful sound considered unpleasant, loud, or disruptive to hearing. 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">Occupational hygiene</span> Management of workplace health hazards

Occupational hygiene is the anticipation, recognition, evaluation, control, and confirmation (ARECC) of protection from risks associated with exposures to hazards in, or arising from, the workplace that may result in injury, illness, impairment, or affect the well-being of workers and members of the community. These hazards or stressors are typically divided into the categories biological, chemical, physical, ergonomic and psychosocial. The risk of a health effect from a given stressor is a function of the hazard multiplied by the exposure to the individual or group. For chemicals, the hazard can be understood by the dose response profile most often based on toxicological studies or models. Occupational hygienists work closely with toxicologists for understanding chemical hazards, physicists for physical hazards, and physicians and microbiologists for biological hazards. Environmental and occupational hygienists are considered experts in exposure science and exposure risk management. Depending on an individual's type of job, a hygienist will apply their exposure science expertise for the protection of workers, consumers and/or communities.

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">Earmuffs</span> Ear-protecting headgear worn over ears to protect from cold or loud noise

Earmuffs are clothing accessories or personal protective equipment designed to cover a person's ears for hearing protection or warmth. They 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 cover the ears.

<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">Occupational hazard</span> Hazard experienced in the workplace

An occupational hazard is a hazard experienced in the workplace. This encompasses many types of hazards, including chemical hazards, biological hazards (biohazards), psychosocial hazards, and physical hazards. In the United States, the National Institute for Occupational Safety and Health (NIOSH) conduct workplace investigations and research addressing workplace health and safety hazards resulting in guidelines. The Occupational Safety and Health Administration (OSHA) establishes enforceable standards to prevent workplace injuries and illnesses. In the EU, a similar role is taken by EU-OSHA.

A recommended exposure limit (REL) is an occupational exposure limit that has been recommended by the United States National Institute for Occupational Safety and Health. The REL is a level that NIOSH believes would be protective of worker safety and health over a working lifetime if used in combination with engineering and work practice controls, exposure and medical monitoring, posting and labeling of hazards, worker training and personal protective equipment. To formulate these recommendations, NIOSH evaluates all known and available medical, biological, engineering, chemical, trade, and other information. Although not legally enforceable limits, RELS are transmitted to the Occupational Safety and Health Administration (OSHA) or the Mine Safety and Health Administration (MSHA) of the U.S. Department of Labor for use in promulgating legal standards.

<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.

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

A noise dosimeter or noise dosemeter is a specialized sound level meter intended specifically to measure the noise exposure of a person integrated over a period of time; usually to comply with Health and Safety regulations such as the Occupational Safety and Health (OSHA) 29 CFR 1910.95 Occupational Noise Exposure Standard or EU Directive 2003/10/EC.

Workplace health surveillance or occupational health surveillance (U.S.) is the ongoing systematic collection, analysis, and dissemination of exposure and health data on groups of workers. The Joint ILO/WHO Committee on Occupational Health at its 12th Session in 1995 defined an occupational health surveillance system as "a system which includes a functional capacity for data collection, analysis and dissemination linked to occupational health programmes".

<span class="mw-page-title-main">Physical hazard</span> Hazard due to a physical agent

A physical hazard is an agent, factor or circumstance that can cause harm with contact. They can be classified as type of occupational hazard or environmental hazard. Physical hazards include ergonomic hazards, radiation, heat and cold stress, vibration hazards, and noise hazards. Engineering controls are often used to mitigate physical hazards.

A short-term exposure limit (STEL) is the acceptable average exposure over a short period of time, usually 15 minutes as long as the time-weighted average is not exceeded.

<span class="mw-page-title-main">Buy Quiet</span>

Buy Quiet is an American health and safety initiative to select and purchase the lowest noise emitting power tools and machinery in order to reduce occupational and community noise exposure. Buy Quiet Programs are examples of noise control strategies. Buy Quiet is part of the larger Hearing Loss Prevention Program, and is an example of Prevention Through Design, which seeks to reduce occupational injury through prevention considerations in designs that impact workers.

<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.

A psychosocial hazard or work stressor is any occupational hazard related to the way work is designed, organized and managed, as well as the economic and social contexts of work. Unlike the other three categories of occupational hazard, they do not arise from a physical substance, object, or hazardous energy.

Engineering controls are strategies designed to protect workers from hazardous conditions by placing a barrier between the worker and the hazard or by removing a hazardous substance through air ventilation. Engineering controls involve a physical change to the workplace itself, rather than relying on workers' behavior or requiring workers to wear protective clothing.

<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.

<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.

References

  1. ↑ "Occupational Noise Exposure: Standards". Occupational Safety and Health Administration. Retrieved 2016-07-14.
  2. ↑ "Reducing Noise Exposure: Guidance & Regulations". www.cdc.gov. 2021-11-08. Retrieved 2022-04-05.
  3. 1 2 US Occupational Safety and Health Administration (1983). "29 CFR 1910.95 Occupational noise exposure". www.osha.gov. Washington, DC: OSHA. Retrieved 18 July 2023.
  4. ↑ Suter, Alice H. (2011-05-24). "Noise. Standards and Regulations". Encyclopaedia of Occupational Health & Safety (Part VI. General Hazards) (4 ed.). International Labour Organization. Retrieved 14 July 2023.
  5. ↑ "Occupational Health and Safety Code". www.alberta.ca. Edmonton: Government of Alberta. 2023. Retrieved 14 July 2023.
  6. ↑ For mental work
  7. ↑ "§ 34". State hygienic requirements 1.2.3685-21 "Hygienic requirements for the safety of environmental factors for humans" [СанПиН 1.2.3685-21 "Гигиенические нормативы и требования к обеспечению безопасности и (или) безвредности для человека факторов среды обитания"] (in Russian). Moscow: Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeing. 2021. p. 337. Retrieved 14 July 2023.
  8. ↑ Bruce, Robert D.; Wood, Eric W. (2003-05-01). "The USA needs a new national policy for occupational noise". Noise Control Engineering Journal. 51 (3). Reston, VA: Institute of Noise Control Engineering: 162-165(4). doi:10.3397/1.2839711. ISSN   2168-8710 . Retrieved 29 July 2023. Quote: Over the past 30 years, there has been a wide range of regulatory action—varying from strict interpretation of the regulation in the early 1970s to a lackadaisical approach today, where an employer willing to hand out ear plugs may get away without a citation unless the time-weighted average level exceeds 100 dB on the A-weighted scale!
  9. 1 2 Suter, Alice (2012). "Engineering Controls for Occupational Noise Exposure - The Best Way to Save Hearing" (PDF). Sound & Vibration. 48 (1). Henderson, Nevada: Tech Science Press: 24–31. ISSN   1541-0161 . Retrieved 7 June 2023.
  10. ↑ Occupational Safety and Health Administration (2010-10-19). "Interpretation of OSHA's Provisions for Feasible Administrative or Engineering Controls of Occupational Noise". Federal Register. Proposed Rule. 44 (201). Washington, DC: Office of the Federal Register: 64216–64221. ISSN   0097-6326 . Retrieved 29 July 2023. p. 64218: ... the majority's adoption of a cost-benefit test amounted to an unauthorized amendment of the standard. Commissioner Cleary’s view
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  12. ↑ "B.9 Extended Workshifts". OSHA Technical Manual. US Occupational Safety and Health Administration. July 6, 2022. Retrieved 18 January 2023. Instrument accuracy must be taken into account ... . Type-2 dosimeters are considered to have an error of ±2 dBA, and the Action Level must be corrected, accordingly. For example, for an 8-hour shift, the corrected Action Level would be 87 dBA ...
  13. ↑ Izmerov, Nikolai; Suvorov, Herman; Prokopenko, Ludmila (2001). "Chapter 4. Occupational hearing loss". The man and the noise (Человек и шум) (in Russian). Moscow: ГЕОТАР-МЕД. p. 103. ISBN   5-9231-0057-6.
  14. ↑ Technical Committee ISO/TC 43 Acoustics (2013). ISO 1999:2013 Acoustics — Estimation of noise-induced hearing loss (3 ed.). Geneva, Switzerland: International Organization for Standardization. p. 23. Retrieved 14 July 2023.{{cite book}}: CS1 maint: numeric names: authors list (link)
  15. ↑ Isaacson, Jon; Vora, Neil M. (2003-09-15). "Differential Diagnosis and Treatment of Hearing Loss". American Family Physician. 68 (6): 1125–1132. ISSN   0002-838X. PMID   14524400.
  16. ↑ "Effects of Noise on The Individual in the Workplace". soundcontroltech.com. Retrieved 2017-05-21.
  17. ↑ "CDC - Hierarchy of Controls - NIOSH Workplace Safety and Health Topic". www.cdc.gov. Retrieved 2018-02-23.
  18. ↑ Bies, David; Hansen, Colin; Howard, Carl (2017). Engineering Noise Control. Boca Raton: CRC Press. p. 248. ISBN   9781351228152.
  19. ↑ "L. Noise Exposure Controls - Overview". OSHA Technical Manual. US Occupational Safety and Health Administration. July 6, 2022. Retrieved 28 July 2023.
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  21. ↑ Jensen, Paul; Jokel, Charles R.; Miller, Laymon N. (December 1978). Industrial Noise Control Manual. DHHS (NIOSH) Publication No 79-117 (Revised ed.). National Institute for Occupational Safety and Health. p. 380. doi:10.26616/NIOSHPUB79117 . Retrieved 29 July 2023.
  22. ↑ Cheremisinoff, Nicholas P. (31 December 1996). Noise Control in Industry. A Practical Guide. Elsevier. p. 203. ISBN   978-0-8155-1399-5 . Retrieved 29 July 2023.
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  24. ↑ Technical Committee, ISO/TC 43/SC 1 Noise (1995). "ISO/TR 11688-1:1995 Acoustics — Recommended practice for the design of low-noise machinery and equipment — Part 1: Planning". iso.org. Geneva, Switzerland: ISO. p. 25. Retrieved 29 July 2023.{{cite web}}: CS1 maint: numeric names: authors list (link)
  25. ↑ Technical Committee, ISO/TC 43/SC 1 Noise (2008). "ISO/TR 11688-2:1998 Acoustics — Recommended practice for the design of low-noise machinery and equipment — Part 2: Introduction to the physics of low-noise design". iso.org. Geneva, Switzerland: ISO. p. 46. Retrieved 29 July 2023.{{cite web}}: CS1 maint: numeric names: authors list (link)
  26. ↑ Technical Committee, ISO/TC 43/SC 1 Noise (2001). "ISO 15664:2001. Noise control design procedures for open plant". iso.org. Geneva, Switzerland: ISO. p. 24. Retrieved 29 July 2023.{{cite web}}: CS1 maint: numeric names: authors list (link)
  27. ↑ Technical Committee, ISO/TC 43/SC 1 Noise (2004). "ISO 17624:2004. Guidelines for noise control in offices and workrooms by means of acoustical screens". iso.org. Geneva, Switzerland: ISO. p. 14. Retrieved 29 July 2023.{{cite web}}: CS1 maint: numeric names: authors list (link)
  28. ↑ Technical Committee, ISO/TC 43/SC 1 Noise (2000). "ISO 15667:2000 Acoustics — Guidelines for noise control by enclosures and cabins". iso.org. Geneva, Switzerland: ISO. p. 50. Retrieved 29 July 2023.{{cite web}}: CS1 maint: numeric names: authors list (link)
  29. ↑ Technical Committee, ISO/TC 43/SC 1 Noise (2020). "ISO 11690-1:2020. Recommended practice for the design of low-noise workplaces containing machinery. Part 1: Noise control strategies". iso.org. Geneva, Switzerland: ISO. p. 29. Retrieved 29 July 2023.{{cite web}}: CS1 maint: numeric names: authors list (link)
  30. ↑ Technical Committee, ISO/TC 43/SC 1 Noise (2020). "ISO 11690-2:2020. Recommended practice for the design of low-noise workplaces containing machinery. Part 2: Noise control measures". iso.org. Geneva, Switzerland: ISO. p. 31. Retrieved 29 July 2023.{{cite web}}: CS1 maint: numeric names: authors list (link)
  31. ↑ Technical Committee, ISO/TC 43/SC 1 Noise (1997). "ISO/TR 11690-3:1997. Recommended practice for the design of low-noise workplaces containing machinery. Part 3: Sound propagation and noise noise prediction in workrooms". iso.org. Geneva, Switzerland: ISO. p. 24. Retrieved 29 July 2023.{{cite web}}: CS1 maint: numeric names: authors list (link)
  32. ↑ Technical Committee, ISO/TC 43/SC 1 Noise (1998). "ISO 14163:1998. Guidelines for noise control by silencers". iso.org. Geneva, Switzerland: ISO. p. 44. Retrieved 29 July 2023.{{cite web}}: CS1 maint: numeric names: authors list (link)
  33. ↑ "Reducing Noise Exposure: Noise Controls". www.cdc.gov. 2021-11-08. Retrieved 2022-04-05.
  34. ↑ "1910.95(b)(1) | Occupational Safety and Health Administration". www.osha.gov. Retrieved 2022-04-04.
  35. ↑ Sokol, Bill (March 1, 2005). "Ear Plugs: A Field Guide". Occupational Health & Safety (Waco, Tex.). 74 (3): 46, 48–50, 52. PMID   15846964 . Retrieved 2022-04-04.
  36. ↑ Groenewold M.R.; Masterson E.A.; Themann C.L.; Davis R.R. (2014). "Do hearing protectors protect hearing?". American Journal of Industrial Medicine. 57 (9). Wiley Periodicals: 1001–1010. doi:10.1002/ajim.22323. ISSN   1097-0274. PMC   4671486 . PMID   24700499 . Retrieved 29 July 2022.
  37. ↑ "Buy Quiet". Centers for Disease Control and Prevention. 25 October 2021.
  38. ↑ "Safe-in-Sound:Excellence in Hearing Loss Prevention Award". Safe-in-Sound. Retrieved 2016-07-14.
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