Of all the hazards faced by workers, noise might be the most insidious. Sure, if you’re with 77,000 Kansas City Chiefs fans in Arrowhead Stadium, with crowd noise cranked up to 142.2 decibels, you’re screaming but you can’t be heard. If you’re standing next to a Top Fuel car that breathes fire at more than 150 decibels, you worry about your eardrum shattering.
But if you’re at a nightclub where noise can reach 100dB, are you thinking about dB levels? Just another night out. If you’re pushing a lawnmower with an average noise of 94dB, are you bothered? You’ve mowed the lawn hundreds of times.
Kansas City Chiefs fans set the record for loudest stadium in the world at 142.2 decibelsThat’s the danger of noise. We get acclimated to it, especially at work. And noise does its damage over time, day after day, year after year, killing inner ear hair cells usually without us realizing we’re slowly losing our hearing. Hearing loss is often discovered and recorded in the annual audiogram required by OSHA for each employee exposed at or above an eight-hour time-weighted average of 85dB. The loss is not always painful. Sure, if you’re standing next to a jackhammer or a gun shot blast without wearing hearing protection, that sonic burst can stun you, leaving your ears temporarily ringing.
But 22 million workers in the U.S. are regularly exposed to potentially damaging noise, according to the Centers for Disease Control. OSHA mandates that any workplace averaging 85dB for an eight-hour average exposure must put in place an effective hearing conservation program. (On construction sites it’s a 90dB threshold.) If you need to raise your voice to speak to someone three feet away, noise levels might be above 85dB.
Hearing conservation programs prevent initial occupational hearing loss, protect remaining hearing and equip workers with the knowledge and hearing protection devicesIndustries most cited by OSHA for hearing protection violations:
Protecting and preserving your hearing can make a huge difference in your quality of life. Permanent hearing loss cannot be corrected through surgery or medicine. Hearing aids can help, but they won’t restore your hearing to normal. Your conversations, taken for granted for so many years, may never be the same. Music, movies, TV shows, podcasts, you’ll have to crank ‘em up and hope you don’t annoy whoever is with you.
OSHA requires employers to follow a hierarchy of controls to keep the noise down in workplaces. The first strategy, installing engineering controls such as modifying or replacing equipment, often is not economically or technically feasible. The second option, limiting the time a person spends at a noise source, is often impracticable. Personal protective equipment in the form of hearing protection devices is the most common line of defense.
Concerning hearing protection and the hierarchy of controls, hearing PPE is the most common line of defenseThere is an assortment of industrial hearing protection devices (HPDs) to choose from:
Other noise canceling earmuffs passively block noise by relying on the insulating materials of the ear cups to dampen sound. They're typically worn in areas where workers don't need to speak with one another and the goal is to block all or most surrounding noise. As the NRR of these earmuffs increases, they tend to get bulkier due to the larger ear cups and increased insulation materials.
Keep in mind no single industrial hearing protector fits all people. Devices address a variety of workplaces environments and conditions, including different decibels levels, specific industries, as well as different communication requirements.
The first step in finding the right hearing protection is to determine what the noise level is in your workplace. OSHA requires measuring noise exposure with a sound level meter or noise dosimeter or both. Measurements should be taken at different times to help determine the different noise levels experienced throughout a workday. Employee movement and sound instrument calibration and maintenance should also be considered in a comprehensive measurement program.
OSHA and ANSI’s sound level estimates chart uses a thermometer-type image to rank on the left side job site sound levels as low as a framing saw (82dB), a backhoe (85dB), and up to a bulldozer (100dB), jackhammer (102dB), grader and scraper (107dB) and a chain saw (110dB). On the right side of the thermometer are everyday sound levels, ranging from a whispered voice (30dB), normal conversation (60dB) to a jet engine at takeoff (140dB) and a gunshot (140dB).
Once the noise level of a work area is determined, you can look at the noise reduction ratings (NRR) of hearing protectors to decide how much attenuation is needed to bring the worker’s exposure below the 85dB threshold. The NRR is a common method for expressing values of noise reduction or attenuation provided by different types of hearing protectors; values range from 0 to approximately 30. The higher the NRR number associated with a hearing protector, the greater the potential for noise reduction.
Skullerz 8880 Hard Hat Mounted Earmuffs are tested and certified to 26dB Noise Reduction Rating (NRR)Noise reduction ratings are important because they indicate the functionality of a device, and the ability of that device to protect hearing in noisy environments.
To approximate an NRR, break out a calculator. Industrial hearing protectors do not reduce the decibel levels in the workplace by the precise decibel reduction number on the NRR label because the hearing protector was tested in a lab, not in the field. Say a person working in a loud occupational environment is exposed to noise at 94dB(A). If the individual is wearing hearing protection equipment with an NRR of about 26dB(A), you would think the noise exposure amount would be lowered to 68dB(A). Wrong. Instead, it would be lowered to 84.5dB(A), below the OSHA threshold of 85dB. How is this calculated? OSHA has methods for estimating the adequacy of hearing protection attenuation. One method’s calculation includes:
What if you are wearing two sets of ear protectors? How is the NRR calculated? This method’s calculation includes:
Training on the proper use of hearing protectors should include individual fit testing to measure how well the devices fit each person.
So what’s best for you? Disposables or reusables? Earplugs or earmuffs? The first thing to do is find adequate protection. Second, make sure the hearing protector is compatible with other PPE or communication devices. And then there is the age-old challenge of compliance – making sure the hearing protection is comfortable and convenient enough to be accepted and worn, not found dangling around the neck, stuffed in a pocket or flipped up on hard hats. Despite decades of knowledge about the dangers of high noise and hearing loss, NIOSH declares occupational hearing loss the most common U.S. work-related illness in manufacturing.
Skullerz 8880 Earmuffs are designed for easy Ergodyne Hard Hat and Safety Helmet integrationProvide your employees with the opportunity to select their hearing protection from a variety of suitable devices. This is a mandate in OSHA noise standard. And it’s one OSHA mandate easily met.
The marketplace for industrial hearing protection features all the types of protection needed for any situation. One example, Skullerz 8880 NRR 26dB Hard Hat Mounted Earmuffs, designed for all-day comfort and for hard hat and safety helmet integration.
Triple up on protection by adding a face shield, earmuffs and a headlamp to Skullerz Hard Hats and Safety HelmetsHow can I protect my hearing at work?
Back to topThe surest method of preventing noise-induced hearing loss (NIHL) is to eliminate the source or to reduce noise at the source by engineering methods. However, in certain situations, these measures are not possible. In such workplaces, workers may need to wear hearing protectors to reduce the amount of noise reaching the ears.
What are some things I should know about selecting hearing protection devices?
Back to topPeople should wear a hearing protector if the noise or sound level they are exposed to is close to or greater than the occupational exposure limits (OEL) for noise. For most jurisdictions, this occupational exposure limit is 85 decibels (A-weighted) or dBA. Hearing protectors reduce the noise exposure level and the risk of hearing loss when worn correctly.
If hearing protection is required, then a complete hearing conservation program should be implemented. A hearing conservation program includes noise assessment, methods for controlling noise, hearing protector selection, employee training and education, audiometric testing, maintenance, inspection, record keeping, and program evaluation.
The effectiveness of hearing protection is reduced greatly if the hearing protectors do not fit properly, are not inserted or worn correctly, if they are worn only periodically, or if they are removed even for a short period of time. To maintain their effectiveness, the hearing protection should not be modified. Music earphones or headsets are not substitutes for hearing protectors and should not be worn where hearing protectors are required to protect against exposure to noise.
Select hearing protection that is:
Earplugs are inserted in the ear canal. They may be premolded (preformed), moldable, rolldown foam, push-to-fit, or custom molded. Disposable, reusable and custom earplugs are available.
Semi-insert earplugs consist of two earplugs held over the ends of the ear canal by a rigid headband.
Earmuffs consist of sound-attenuating material and soft ear cushions that fit around the ear and hard outer cups. They are held together by a headband.
The choice of hearing protectors is a very personal one and depends on a number of factors including level of noise, comfort, and the suitability of the hearing protector for both the worker and the environment. Most importantly, the hearing protector should provide the desired noise reduction. It is best, where hearing protectors must be used, to provide a choice of a number of different types and sizes to choose from.
If the noise exposure is intermittent, earmuffs are more desirable since it may be inconvenient to remove and reinsert earplugs.
Manufacturers provide information about the noise-reducing capability of a hearing protector, referred to as an NRR (noise reduction rating) value. The NRR is based on laboratory conditions, therefore, calculations to de-rate the noise reduction rating should be done to reflect workplace conditions (see further below).
CSA Standard Z94.2-14 (R2019) “Hearing protection devices — Performance, selection, care, and use” defines noise reduction rating as “a single number rating that indicates the overall hearing protector attenuation, computed as the difference between the overall C-weighted level of a noise spectrum having equal energy per octave and the A-weighted noise levels under a hearing protector, using mean attenuation data less two standard deviations, derived from the experimenter-fit-procedure of the 1974 edition of ANSI Z3.19 (withdrawn) as defined in EPA (1979)”.
The NRR, or other similar systems such as the single number rating (SNR), is a method to more accurately determine the effective exposure of a person when wearing a hearing protector. These rating systems attempt to estimate the actual sound protection provided by hearing protectors when worn in actual working environments (vs. laboratory testing situations). The “real world” results are often different than laboratory tests with the main reasons for this difference being poor fit, and lack of proper training, supervision, and enforcement. For these reasons, training on the correct fit, and making sure users have a thorough understanding of hearing loss are important elements of the hearing conservation program.
Detailed calculations of the protection provided by a hearing protector involve using octave band analysis of the workplace noise and the noise attenuation provided by the hearing protector for noise in each octave band. Attenuation is defined by CSA Standard Z94.2-14 (R2019) “Hearing protection devices — Performance, selection, care, and use” as “the reduction in sound pressure level incident upon the ear due to the application of a hearing protector or, specifically, the change in hearing threshold level that results when a hearing protector is worn.”
Calculating noise attenuation of hearing protection and de-rating noise reduction values (NRR)
Source: CSA Z94.2-14 (R2019) “Hearing protection devices — Performance, selection, care, and use” Table 2
Earplugs
Percent of NRR achieved: 50%
For use with dBA: Leq – [NRR (0.50) – 3] = XX dBA
For use with dBC: Lceq – NRR (0.5) = XX dBA
Earmuffs
Percent of NRR achieved: 70%
For use with dBA: Leq – [NRR (0.7) – 3] = XX dBA
For use with dBC: Lceq – NRR (0.7) = XX dBA
Dual Protection (use of earplugs and earmuffs)
Percent of NRR achieved: 65%
For use with dBA: Leq– [(NRR + 5) (0.65) – 3] = XX dBA
For use with dBC: Lceq – (NRR + 5) (0.65) = XX dBA
The NRR used for dual-protection calculations is higher of the individual NRRs of the two devices.
Note: Certain CSA Group standards are available for online viewing. To access these, you must first create an account with “CSA Communities”.
Go to: "https://community.csagroup.org/login.jspa?referer=%252Findex.jspa"
Once you are logged in, click on the text below the “OHS Standards / View Access” graphic.
Click on the jurisdiction of your choice to see the CSA Standards as referenced in that legislation.
Standards may also be purchased from CSA Group: "https://store.csagroup.org/"
As an example:
Measured workplace noise time-weighted average (TWA) exposure = 98 dBA
Earplug with NRR = 29 dB
Estimated noise exposure = 98 – [29(0.5) - 3] = 86.5 dBA
CSA Standard Z94.2-14 (R2019) provides further guidance on how to apply NRR calculations.
Both types of hearing protection offer advantages and disadvantages.
Earplugs can be mass-produced or individually molded to fit the ear. They can be reusable or disposable. On the positive side, they are simple to use, less expensive than muffs, and often more comfortable to wear when in hot or damp work areas. Some disadvantages are they provide less noise protection than some muffs, and should not be used in areas exceeding 105 dBA. Earplugs are less visible than muffs, making it more difficult to confirm if they are worn. They must be properly inserted and inserted hygienically to provide adequate protection.
Earmuffs can vary with respect to the material and depth of the dome and the force of the headband. The deeper and heavier the dome, the greater the low-frequency attenuation provided by the protector. The headband must fit tightly enough to maintain a proper seal, yet not be too tight for comfort. Some advantages are that earmuffs usually provide greater protection than plugs, although this is not always true. They are easier to fit, generally more durable than plugs, and they have replaceable parts. On the negative side, they are more expensive and often less comfortable than plugs, especially in hot work areas. In areas where noise levels are very high, muffs and plugs can be worn together to give better protection.
The following table summarizes the differences between earplugs and earmuffs.
Comparison of Hearing ProtectionEarplugsEarmuffsAdvantages:
Advantages:
may be worn with minor ear infections
Disadvantages:
Disadvantages:
The human aspects of hearing protection are particularly important since the only useful kind of protection is the protection that is actually worn. Some people do not accept particular kinds of protectors; every human being is different, and the anatomy of the ear and ear canal can vary significantly from person to person.
It is a good idea for the employer to provide a number of different types and sizes of hearing protection from which workers can choose, keeping in mind any safety or hygienic reasons for not providing a particular kind of protector. That is, a particular type of protector should not be used if noise levels are too high or if it proves to be inadequate from a hygienic point of view. For example, earplugs which are used in a plant setting where people reuse them throughout the day, often reinserting them with dirty fingers, can introduce dirt and bacteria into the ears, causing ear infections.
The bottom line on hearing protection is worker preference. If the workers do not like the type of protection (for example, if it is uncomfortable, does not fit well, or is impractical), they will not wear it.
Follow the manufacturer's instructions. With earplugs, for example, the ear should be pulled outward and upward with the opposite hand to enlarge and straighten the ear canal, and insert the plug with clean hands.
In order to get the full benefit, hearing protectors must be worn all the time during noisy work. If hearing protectors are removed only for a short duration, the protection is substantially reduced. The following table gives a maximum protection provided for non-continuous use of an ideally fitted 100% efficient hearing protector. For example, when hearing protection is rated with an attenuation of 25dB, if one takes off their hearing protector for 5 minutes in an hour the maximum protection will be reduced to no more than 11dB.
Impact of removing hearing protectorTime removed (in 1 hr)Maximum 25 dB protection is reduced to (dB)0 minno reduction1 min175 min1110 min830 min360 min0Source: Removal of hearing protectors severely reduces protection. Health and Safety Executive, UK (no date)
Hearing protectors must be used ALL THE TIME to get the full benefit.