Hearing conservation program

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Hearing conservation programs are designed to prevent hearing loss due to noise and other environmental factors in different segments of society. Regarding occupational exposures to noise, a written 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 measured on the A scale (slow response) or, equivalently, a dose of fifty percent."[1] 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,[2] and requires has almost the same exact requirements as the OSHA hearing conservation program requirements. Therefore, only the OSHA standard 29 CFR 1910.95 will be discussed in detail.

Workers cutting marble without any protective gear. Photo taken in Indore, India

Program requirements[edit]

The OSHA standard contains a series of program requirements.

  • Engineering Controls: 29 CFR 1910.95(b)(1) requires that "feasible administrative or engineering controls shall be utilized. If such controls fail to reduce sound levels...personal protective equipment shall be provided and used to reduce sound levels..."
  • Monitoring: 29 CFR 1910.95(d) requires that monitoring be conducted when "any employee's exposure may equal or exceed an 8-hour time-weighted average of 85 decibels.
  • Testing: 29 CFR 1910.95(g) requires an "audiometric testing program" for "all employees whose exposures equal or exceed an 8-hour time-weighted average of 85 decibels".
  • Hearing Protectors: 29 CFR 1910.95(i) states that "employers shall make hearing protectors available to all employees exposed to an 8-hour time-weighted average of 85 decibels or greater at no cost to the employees"
  • Training: 29 CFR 1910.95(k) mandates an annual "training program" for "all employees who are exposed to noise at or above an 8-hour time-weighted average of 85 decibels..." and mandates certain aspects of the training that must be included. This includes the effects of noise on hearing; purpose, advantages, disadvantages, and attenuation of different types of hearing protectors; purpose audiometric testing.
  • Record Keeping: 29 CFR 1910.95(m) states that employers "shall maintain an accurate record of all employee exposure measurements..."

Sound survey[edit]

A sound survey is often completed to determine areas of potential high noise exposure. This type of survey is normally completed using a sound level meter (SLM). There are three types of sound level meters. Type 0 is precision instrument normally used in laboratories. A type 1 is for precision measurements taken in the field. Type 2 sound level meters are less precise than type 1 and are often used to take all-purpose sound level measurements. Noise monitoring is generally completed using a noise dosimeter that integrates "all continuous, intermittent and impulsive sound levels"[3] to determine a person's noise exposure level.

Surveys must be repeated when there are significant changes in machinery and/or processes that would affect the noise level.[4]

Engineering and administrative controls[edit]

Engineering controls and administrative controls are the preferred method to prevent noise exposure. Normally, they do not require personal protective equipment and therefore are normally more protective. However, it is not always feasible to use administrative and engineering controls as the only ways to prevent noise over-exposure. The key is to maintain an 8-hour time-weighted average of less than 85 dBA so that personal protective equipment is not required. On October 19, 2010, the US Department of Labour proposed that the term "feasible" be interpreted as that which is capable of being done, thus enhancing OSHA's ability to enforce this aspect of the standard.[5]

Hearing protection device[edit]

If engineering controls fail to maintain an 8-hour time-weighted average below 85 dBA, then a hearing protection device (HPD) is required. There are two general types of HPDs: earplugs and earmuffs. Each one has its own benefits and drawbacks. The selection of the proper HPD to be worn is commonly done by an industrial hygienist so that the proper amount of noise protection is worn. OSHA requires that HPD be given free of charge.[6]

Earplugs[edit]

There are four general classes of earplugs. These include: premolded, formable, custom molded and semi-insert.

  • Premolded earplugs do not require the plug to be formed before it is inserted into the ear. This prevents the plugs from becoming soiled before insertion.
  • Formable earplugs are made of a variety of substances. However, all each substance shares the common feature of being able to be shaped by the user prior to insertion. One drawback of this is the obvious need for the user to have clean hands while shaping the earplug. They do have the advantage of forming to the users ear, while many premolded earplugs do not accomplish this very well.
  • Custom molded ear plugs are unique for each person, since they are cast from each user's own ear canals. Therefore, they provide a personalized fit for each individual.
  • Semi-inserts are generally a soft earplug on the end of band. The band aides in maintaining the earplug in position. They are often useful since they can be quickly removed and inserted.

Earmuffs[edit]

Earmuffs are another type of HPD. The main difference between earmuffs and earplugs, is that earmuffs are not inserted inside the ear canal. Instead the muffs create a seal around the outside of the ear to prevent noise from reaching the inner ear. Earmuffs are easy to wear and often provide a more consistent fit than an earplug. There are earmuffs available that use the principle of active noise control to help reduce noise exposures. However, the protection earmuffs offer may be mitigated by large sideburns or glasses as the seal of the earmuffs may be broken by these objects.[7]

Noise reduction ratings[edit]

The United States Environmental Protection Agency (EPA) requires that all hearing protection devices be labeled with their associated noise reduction rating (NRR).[8] The NRR provides the estimated attenuation of the hearing protection device. However, it has been found that the "labeled manufacturers' noise reduction ratings (NRRs) substantially overestimated the actual field attenuation performance."[9][10] To determine the amount of noise reduction afforded by a hearing protection device, OSHA recommends that 7 db be subtracted from the NRR. The NRR is generally given in a C-weighted format, so to obtain the A-weighted reduction, one must subtract 7 db. OSHA also recommends a 50% safety factor, therefore the final OSHA recommended reduction would be (NRR-7)/2.[11]

Fit Testing for Hearing Protection

The NRR now has some help. Fit testing devices on the market that will verify a proper fit of an HPD (hearing protection device). The fit of a hearing protector is very important, because if the HPD is not worn properly, the NRR becomes irrelevant. Products that will verify proper fit include: 3M EARFit Validation System, FitCheck, FitCheck Solo, INTEGRAfit, SafetyMeter, and VeriPro. Fit-test systems provide a Personal Attenuation Rating (PAR) that is currently dependent upon the company that manufactures the fit-testing system. Most fit test systems provide an A-weighted PAR, which means that the attenuation can be subtracted from the A-weighted noise exposure assessment of the employee or hearing protector user.[12]

System Method Test Frequencies Test Signal To Use PAR with

A-weighted Noise

Additional Notes
3M EARFit

Validation System

F-MIRE 125–8000 Hz Broadband Noise Subtract Directly Provides 20th and 80th percentile

Confidence Interval

Michael & Assoc.

FitCheck

REAT

under headphones

125–8000 Hz 1/3 Octave Band Noise Subtract directly
Michael & Assoc.

FitCheck Solo

REAT

under headphones

125–8000 Hz 1/3 Octave Band Noise Subtract directly Provides a 95% confidence interval
Workplace Integra

INTEGRAFIt

REAT

under headphones

0.5, 1, & 2 KHz Tone Subtract directly
Phonak SafetyMeter

Fit-TestSystem

F-MIRE 125–8000 Hz Broadband Noise Subtract 7 dB from PAR

then subtract directly

Subtract directly from

C-weighted noise levels

Honeywell

VeriPRO

Loudness Balance

under headphones

250–4000 Hz Tone alternating ears Subtract directly

Table: Fit-testing systems, PAR measurement method and application to estimate protected exposure level.[12]

Audiometric testing program[edit]

Audiometric testing is a very important part of a hearing conservation program. Audiometric testing allows for the identification of those that have lost significant hearing. Additionally, the testing allows for the identification of those who are in process of losing their hearing. Audiometric testing is most important in identifying those who have permanent hearing loss. This is called noise-induced permanent threshold shift (NIPTS).[13]

Completing baseline audiograms and periodically monitoring threshold levels is one way to track any changes in hearing and identify if there is a need to make improvements to the HCP. The Occupational Safety and Health Administration (OSHA), which monitors workplaces in the United states to ensure safe and healthful working conditions, specifies that employees should have a baseline audiogram established within 6 months of their first exposure to 85 dBA time-weighted average (TWA). If workers are unable to obtain baseline within 6 months, they are required to wear hearing protection devices (HPD) whenever they are exposed to 85 dBA or above TWA until they have obtained a baseline audiogram.[14] Under the Mine Safety and Health Administration (MSHA), which monitors compliance to standards within the mining industry, an existing audiogram that meets specific standards can be used for the employee’s baseline. Before establishing baseline, it is important that the employee limit excessive noise exposure that could potentially cause a temporary threshold shift and affect results of testing. OSHA stipulates that an employee be noise-free for at least 14 hours prior to testing.[14]

Periodic audiometric monitoring, typically completed annually as recommended by OSHA, can identify changes in hearing. There are specific criteria that the change must meet in order to require action. The criterion most commonly used is the standard threshold shift (STS), defined by a change of 10 dB or greater averaged at 2000, 3000, and 4000 Hz.[14] Age correction factors can be applied to the change in order to compensate for hearing loss that is age-related rather than work-related. If an STS is found, OSHA requires that the employee be notified of this change within 21 days.[14] Furthermore, any employee that is not currently wearing HPD is now required to wear protection. If the employee is already wearing protection, they should be refit with a new device and retrained on appropriate use.[14]

Another determination that is made includes whether an STS is “recordable” under OSHA standards, meaning the workplace must report the change to OSHA. In order to be recordable the employee’s new thresholds at 2000, 3000, and 4000 Hz must exceed an average of 25 dB HL.[14] MSHA standard differs slightly in terms of calculation and terminology. MSHA considers whether an STS is “reportable” by determining if the average amount of change that occurs exceeds 25 dB HL.[14] The various measures that are used in occupational audiometric testing allow consistency in standards within workplaces. Completing baseline and follow-up audiograms allows workplaces to detect hearing loss as early as possible and determine whether changes need to be made to provide a safe working environment for their employees.

Employee training and education[edit]

Proper training and education of those exposed to noise is the key to preventing noise-induced hearing loss. If employees are properly trained on how to follow a hearing conservation program, then the risk of noise-induced hearing loss is reduced. By providing information on the physiological effects of noise exposure, the importance of obtaining baseline and annual audiograms, and use of appropriate hearing protection, the program will provide a thorough knowledge base for employees involved. Providing a refresher training when appropriate will ensure retention of this information as well.[15] OSHA requires said training to be completed on an annual basis. Proper training is imperative since "even with a very modest amount of instruction attenuation performance can be significantly improved."[16][17]

Motivating Employees to Follow a Hearing Conservation Program[edit]

Even with training and education, the workers need to be motivated to use hearing protection on a regular basis for the hearing conservation program to be successful.[12] Even if workers are aware that noise can cause hearing loss, that does not guarantee that they will take the necessary actions to preserve their hearing.[12]

There are several reasons why a worker may choose not to adopt the protocols of a hearing conservation program. Employees may not follow protocol because they feel that noise induced hearing loss will not happen to them.[12] They may believe this because they think the level of sound that they are exposed is not loud enough to cause hearing loss or that loud noise just toughens their ears. They might also think hearing loss is not a serious condition and can easily be fixed with hearing aids.[12] Another reason is the worker may believe that hearing protection does not actually work and that he/she may still develop noise-induced hearing loss even with hearing protection.[12] If the employee feels that hearing protection may impinge his/her work, whether it be missing important warning signals or the ability to communicate, he/she is less likely to wear it.[12] Finally, the comfort of the hearing protection offered through the hearing conservation program.[18] If the hearing protection is uncomfortable, it is unlikely that the worker will adhere to the policies.[18]

Motivational techniques can be implemented to promote hearing conservation program compliance and the use of hearing protection. One suggestion is continued education at the workers' audiometric screening.[18] They should be asked to bring along their current hearing protection device to the screening. If the results are normal and the inspection of the hearing protection device is good, praise can be given for following protocol. If there is a shift in their hearing, instruction can be given again about the proper use of hearing protection and the importance of wearing them. Audiograms can be very useful in showing workers how noise can affect their hearing. One specific way to do this is to perform two hearing test on an employee on two different days.[18] One day the hearing test will be after wearing hearing protection all day and the other will be after not wearing hearing protection for the day. The difference can then be discussed with the worker and he/she has a tangible way to see how noise affects hearing. Another technique is using "internal triggers" to motivate employees to comply to the hearing conservation program.[12] If the individual already suffers from tinnitus and/or hearing loss they are probably more likely to use hearing protection because he/she does not want that problem to progress with noise exposure. Finally, the hearing protection offered should be comfortable so the worker will wear it. It is suggested that workers have a variety of hearing protection devices available to them, including at least one type of earmuff and two different forms of earplugs, to fit the individual needs and wants of the workers.[18]

Record keeping[edit]

OSHA requires that records of exposure measurements and audiometric tests be maintained. Records are also required to have the following:

  • name and job classification
  • date of the audiogram
  • examiner's name
  • calibration date
  • employee's most recent noise exposure assessment
  • background sound pressure levels in audiometric test booths.

Noise exposure measurement records must be maintained for at least 2 years. Audiometric test records must be retained for the duration of the affected employee's employment. Additionally, employees, former employees, representatives designated by the individual employee and the Assistant Secretary all must have access to these records.[19]

Program evaluation[edit]

Proper program evaluation is important in maintaining the health of hearing conservation program. The National Institute for Occupational Safety and Health (NIOSH) has created a checklist to help evaluate the effectiveness of a hearing conservation program. It can be found on their website.[20] NIOSH recommends that fewer than 5% of exposed employees should have a 15 dB Significant Threshold Shift in the same ear and same frequency.

The National Institute for Occupational Safety and Health is pushing a higher emphasis on a hearing loss prevention program rather than a hearing conservation program. While this change may seem superfluous, it is important to note the advancement. Prevention implies a response by the workplace caused by initial signs of employee hearing loss rather than instilling a new set of policies (such as "buy quiet") and thinking (such as hearing protection training and education) to decrease the possibility of occupational hearing loss from happening in the first place.

The Buy Quiet policy is an easy way to progress towards a safer work environment. Many traditionally noisy tools and machines are now being redesigned in order to manufacture quieter running equipment, so a "buy quiet" purchase policy should not require new engineering solutions in most cases.[21] As a part of the "buy quiet" campaign, the New York City Department of Environmental Protection released a products and vendor guidance sheet in order to assist contractors for achieving compliance with the New York City Noise Regulations.

In order to make these plans effective, employees and administration need to be educated in occupational noise-induced hearing loss prevention. It is also necessary to identify and examine sources of noise first before being able to control the damage it may cause to hearing. For example, the National Institute for Occupational Safety and Health has conducted a study and created a database on handheld power tools for the sound power levels they expose their operators to. This Power Tools Database allows contractors in a trade-skill profession to monitor their exposure limits and allow them preparation to prevent permanent hearing damage.

Hearing conservation for children[edit]

Overview[edit]

Due to increased worry among both parents and experts regarding Noise-induced hearing loss (NIHL) in children, it has been suggested that hearing conservation programs be implemented in schools as part of their studies regarding health and wellness. The necessity for these programs is supported by the following reasons: 1. Children are not sheltered from loud noises in their daily lives, and 2. Promoting healthy behaviors at a young age is critical to future application.[22] The creation of a hearing conservation program for children will strongly differ from those created for the occupational settings discussed above. While children may not be exposed to factory of industrial noise on a daily basis, they may be exposed to noise sources such as firearms, music, power tools, sports, and noisy toys. All of these encounters with noise cumulatively increases their risk for developing Noise-induced hearing loss. With NIHL being a fully preventable ailment, providing children with this type of education has the potential to reduce future incidence of this condition. There are multiple organizations in existence that provide educators with the appropriate material to teach this topic; teachers simply need to be proactive about accessing them.[23] Below are examples of hearing conservation programs that have been designed specifically for children.

Creation of Programs[edit]

This is the primary goal of most hearing conservation programs at the elementary, middle, and high school levels is to spread knowledge about hearing loss and noise exposure. When an educational program is being created or adapted for use with children, behavior change theories are often employed to increase effectiveness. Behavior theory[disambiguation needed] identifies possible obstacles to change while also highlighting factors that may encourage students to change.[18] The following are elements that are also considered during the implementation of a new program for children:

1. Adaptation of the program for the specific population (age, demographic, etc.)

2. Use of interactive games, lessons, and role-playing

3. Time to apply the skills that are taught

4. Reoccurring lessons on the same topic area[18]

Examples of Programs & Campaigns[edit]

Dangerous Decibels[edit]

Dangerous Decibels is a program designed to teach concepts related to the prevention of noise-induced hearing loss. Proven to be effective for children in 4th through 7th grade, children are engaged in hands-on activities during this 50-minute presentation. The class will learn about what sound is, how their ears hear and detect it, and how they can protect their hearing from dangerous decibels. Throughout the program, the class focuses on three strategies: Turn it Down, Walk Away, and Protect your Ears.[24]

Listen to your Buds[edit]

Created by the American Speech-Language-Hearing Association, this campaign aims to teach children and their parents about practicing safe listening routines when listening to music through personal devices, such as an iPod. With the help of sponsors, ASHA hosts an educational concert series to promote safe music listening.[25]

Cheers for Ears[edit]

Run by the Ear Science Institute of Australia, this school program was created to educate elementary-age children on the risks of high listening levels and the effects of hearing loss. Program has a mascot named Charlie and utilizes sound level meters, computer games, apps, and take-home packets to teach the concepts. Teachers also receive addition activities and worksheets for continued learning opportunities.[26]

It's a Noisy Planet. Protect Their Hearing.[edit]

Organized by the United States National Institutes of Health, this is a campaign created with the aim to increase parental awareness of both the causes and effects of noise induced hearing loss. By targeting parents instead of children, the goal is for adults to influence the behaviors of their children before bad habits are even created. Resources provided include web-based games and puzzles, downloadable graphics, and tips for school and home environments.[27]

Sound Sense[edit]

Created by The Hearing Foundation of Canada, the Sound Sense classroom program teaches children how hearing works, how it can stop working, and offers ideas for safe listening. The classroom presentation satisfies the requirements for the science unit on sound taught in either grade 3 or 4, as well as the healthy living curriculum in grades 5 and 6. In addition, the webpage provides resources & games for children, parents, and teachers.[28]

HEARsmart[edit]

An Australian program initiated by the HEARing Cooperative Research Centre and the National Acoustic Laboratories (NAL), HEARsmart aims to improve the hearing health of all Australians, particularly those at greatest of risk of noise-related tinnitus and hearing loss. The program has a particular focus on promoting healthy hearing habits in musicians, live music venues and patrons. Resources include: Know Your Noise - an online risk calculator and speech-in-noise test, a short video that aims to raise awareness of tinnitus in musicians, and a comprehensive website with detailed information.[29]

Effectiveness & Program Evaluation[edit]

Just as program evaluation is necessary in workplace settings, it is also an important component of educational hearing conservation programs to determine if any changes need to be made. This evaluation may consist of two main parts: assessment of students' knowledge and assessment of their skills and behaviors. To examine the level of knowledge acquired by the students, a questionnaire is often given with the expectation of an 85% competency level among students. If proficiency is too low, changes should be implemented. If the knowledge level is adequate, assessing behaviors is then necessary to see if the children are using their newfound knowledge. This evaluation can be done through classroom observation of both the students and teachers in noisy classroom environments such as music, gym, technology, etc.[30]

Other Regulatory Agencies[edit]

The Mine Safety and Health Administration (MSHA) requires that all feasible engineering and administrative controls be employed to reduce miners' exposure levels to 90 dBA TWA. The action level for enrollment in a hearing conservation program is 85 dBA 8-hour TWA, integrating all sound levels between 80 dBA to at least 130 dBA. MSHA uses a 5-dB exchange rate (the sound level in decibels that would result in halving [if an increase in sound level] or a doubling [if a decrease.in sound level] the allowable exposure time to maintain the same noise dose). At and above exposure levels of 90 dBA TWA, the miner must wear hearing protection. At and above exposure levels above 105 dBA TWA, the miner must wear dual hearing protection. Miners may not be exposed to sounds exceeding 115 dBA with or without hearing protection devices. MSHA defines a standard threshold shift as an average decrease in auditory sensitivity of 10 dB HL at the frequencies 2,000, 3,000, and 4,000 Hz. (30 CFR Part 62[31]).

The Federal Railroad Administration (FRA) encourages, but does not require, railroads to use administrative controls that reduce noise exposure duration when the worker exceeds 90 dBA TWA. The FRA defines the action level for employee enrollment in a hearing conservation program as an 8-hour TWA of 85 dBA on certain railroads, integrating all sound levels between 80 dBA and 140 dBA. FRA uses a 5-dB exchange rate. Those employees who are always at or above 90 dBA TWA are required to wear hearing protection such that sound levels are attenuated below 90 dBA TWA. (49 CFR Part 229[32]).

The U.S. Department of Defense (DOD) specifies that engineering controls are preferential when reducing the noise levels at the source. The use of hearing protective devices is considered an "interim protective measure" while engineering controls are developed. The goal of these controls is to reduce ambient steady-state noise levels to 85 dBA regardless of TWA exposure and to reduce impulse noise levels to below 140 dBP. The DOD requires that personnel be entered into a hearing conservation program when continuous snd intermittent noise levels ale grs greater than or equal to 85 dBA TWA, when impulse SPL are at or in excess of 140 dBP, or when the personnel is exposed to ultrasonic frequencies. The DOD integrates all sound levels between 80 dBA to a minimum of 130 dBA when determining an individual or representative noise dose. When used, hearing protectors must be capable of attenuating worker noise exposure below 85 dBA TWA. Hearing protection is required to be carried by personnel who work in designated noise areas, such as those exposed to gunfire or ordnance tests and Service musicians. The DOD defines a significant threshold shift as a 10 dB average decrease in hearing thresholds at 2,000, 3,000, and 4,000 Hz in either ear, with no age corrections. It is further specified that a shift in 15 dB at 1,000, 2,000, 3,000, or 4,000 Hz is an early warning sign for an STS; follow-up retraining is required in this case. (DOD Instruction 6055.12[33]).

The European Union (EU) requires a hearing conservation program be implemented when the worker exposure levels exceed 80 dBA TWA. Note that this is more strict than hearing conservation regulations in the United States. The EU specifies several different exposure action values: a "lower" value of 80 dBA at which the employer must make hearing protection devices available to the employee; an "upper" value of 85 dBA at which the employee is required to wear hearing protection; and an "exposure limit" value of 87 dBA, under which the individual's noise exposure shall be limited to preserve hearing. The directive also defines a weekly noise exposure level which is applied to individuals working in circumstances of inconstant noise exposure. Finally, the EU also recommends a variety of noise reduction methods, including administrative controls to reduce worker exposure duration, the provision of quieter equipment, and adequate maintenance of machinery and other noise sources (European Parliament and Council Directive 2003|10|EC[34]).

See also[edit]

References[edit]

  1. ^ 29 CFR 1910.95(c)(1)
  2. ^ 30 CFR § 62.150
  3. ^ 29 CFR 1910.95(d)(2)(i)
  4. ^ OSHA 1910.95 appendix (G)
  5. ^ Federal Register / Vol. 75, No. 201 / Tuesday, October 19, 2010 / Proposed Rules
  6. ^ 29 CFR 1910.95(i)(1)
  7. ^ Stephenson, Carol Merry. "Choosing the Hearing Protection That's Right For You". Retrieved 2017-02-03. 
  8. ^ 40 CFR code of Federal Regulations, Part 211, Product Noise Labeling, Subpart B - Hearing Protection Devises
  9. ^ Park, MY; Casali, JG (December 1991)."A controlled investigation of in-field attenuation performance of selected insert, earmuff, and canal cap hearing protectors". Human Factors 33(6): 693-714
  10. ^ Berger EH, Franks JR, Behar A, Casali JG, Dixon-Ernst C, Kieper RW, Merry CJ, Mozo BT, Nixon CW, Ohlin D, Royster JD, and Royster LH. (1998) Development of a new standard laboratory protocol for estimating the field attenuation of hearing protection devices. Part III. The validity of using subject-fit data. J. Acoust. Soc. Am., 102:665-672.
  11. ^ CPL 02-02-035 - CPL 2-2.35A - 29 CFR 1910.95(b)(1), Guidelines for Noise Enforcement; Appendix A
  12. ^ a b c d e f g h i Murphy, William (2013). "Comparing Personal Attenuation Ratings for Hearing Protector Fit-test Systems" (PDF). CAOHC Update. Retrieved June 13, 2016. 
  13. ^ Noise and Hearing Conservation Technical Manual Chapter: Noise and Health Effects (App I:C)
  14. ^ a b c d e f g Rawool, V.W. (2012). Hearing Conservation in Occupational, Recreational, Educational, and Home Settings. New York: NY: Thieme Medical Publishers, Inc. pp. 65–105. 
  15. ^ Rawool, V.W. (2012). Hearing Conservation in Occupational, Recreational, Educational and Home Settings. New York: NY: Thieme Medical Publishers. pp. 174–186. 
  16. ^ Williams, W. (2004). "Instruction and the improvement of Hearing Protector Performance" Noise and Health Oct-Dec;7(25):41-77 http://www.noiseandhealth.org/article.asp?issn=1463-1741;year=2004;volume=7;issue=25;spage=41;epage=47;aulast=Williams
  17. ^ Joseph A, Punch J, Stephenson M, Wolfe E, Paneth N, Murphy W (2007). The Effects of Training Format on Earplug Performance. Int J Audiology 46:609-618
  18. ^ a b c d e f g Martin, William Hal; Sobel, Judith; Griest, Susan E.; Howarth, Linda; Yongbing, Shi (2006-06-01). "Noise Induced Hearing Loss in Children: Preventing the Silent Epidemic". Journal of Otology. 1 (1): 11–21. doi:10.1016/S1672-2930(06)50002-9. 
  19. ^ 29 CFR 1910.95(m)
  20. ^ Noise and Hearing Loss Prevention: Hearing Conservation Program Checklist National Institute for Occupational Safety and Health
  21. ^ John R. Franks; Mark R. Stephenson; Carol J. Merry, eds. (1996). "PREVENTING OCCUPATIONAL HEARING LOSS — A PRACTICAL GUIDE" (PDF). U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES. 
  22. ^ Rawool, Vishakha Waman (2012). Hearing Conservation. Theime Medical Publishers. p. 283. 
  23. ^ Folmer, Robert (2008-02-01). "Hearing-Loss Prevention Practices Should Be Taught in Schools". Seminars in Hearing. 29 (1): 067–080. doi:10.1055/s-2007-1021774. ISSN 0734-0451. 
  24. ^ "The Dangerous Decibels Classroom Presentation". 
  25. ^ "Listen to Your Buds". 
  26. ^ "Cheers for Ears". 
  27. ^ "It's a Noisy Planet. Protect Their Hearing". 
  28. ^ "Sound Sense". 
  29. ^ "HEARsmart". 
  30. ^ Rawool, Vishakha Waman (2012). Hearing Conservation. New York, NY: Theime Medical Publishers, Inc. pp. 292–293. 
  31. ^ "30 CFR Part 62". eCFR - Code of Federal Regulations. 
  32. ^ "49 CFR Part 229". eCFR - Code of Federal Regulations. 
  33. ^ "DOD Instruction 6055.12" (PDF). 
  34. ^ "DIRECTIVE 2003/10/EC OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL" (PDF). 

External links[edit]