The Occupational Safety and Health Administration (OSHA) has official limits on the decibel level American workers can be exposed to during an 8-hour shift. OSHA's permissible exposure limit is 90 A-weighted decibels (dBA) over 8 hours. However, the organization also states that for every 5 dBA increased, the amount of time the worker can be exposed reduces by 50 percent.
To elaborate further, a worker can safely be exposed to 90 dBA for 8 hours, but if the noise level increases to 95 dBA, they can only be exposed for 4 hours before suffering hearing damage. That is, unless they are wearing adequate hearing protection.
One of the biggest advantages of ear muffs is that they don’t need to be custom fit. Most models are designed as a one-size-fits-all solution, and some can be easily adjusted to fit snugly on the wearer’s head. Because of their size, they’re easy to see and hard to lose. In addition to protecting employees from loud noises, they also keep their ears warm, making them ideal for those whom have to brave cold temperatures on the job, such as construction workers and landscapers.
While they can do a lot of good, ear muffs do come with their fair share of disadvantages. For one, they can be extremely uncomfortable in hot and humid conditions. Because they fit snugly over the ears, they do a great job of trapping in heat, which isn’t ideal when temperatures reach 80 degrees or higher. Also, people with glasses may have difficulties because the ear hooks may prevent the muffs from securely fitting. Additionally, since they don’t directly block the ear canal, ear muffs may not provide as good of a seal against extreme noise in comparison to ear plugs.
Because they fit directly into the ear canal, ear plugs offer a higher level of protection from noise than ear muffs.
Those employed in factories, foundries, or on the tarmacs at airports are suitable candidates for this type of ear protection. They are easy for a worker to carry with them in a sealable plastic baggie or a hard-shell case. And, for workers wearing glasses or a safety helmet, there is no discomfort or interference.
On the negative side, ear plugs are sometimes hard to fit in the ear. Some instructions require the wearer to pull their ear at a certain angle, ball up the ear plug, and then stick it in their ear canal. If done incorrectly, the ear plug will constantly slip out of the ear canal and not protect the wearer as well as it should. Additionally, their small size makes them easy to lose and hard to see when inside the wearer’s ear.
It depends on the needs of the worker. Ear muffs will get the job done in most situations, but may cause discomfort in areas with higher temperatures. On the other hand, ear plugs fit directly into the ear canal and offer maximum protection from excessive noise. Their only downside is their size. They aren’t the easiest to fit, and they are so small that they can easily be lost.
No matter which is chosen, it’s wise to pay attention to the decibel (dB) rating. Both ear plugs and ear muffs come with a dB rating that tells the user how much noise reduction there will be when the product is worn. For example, if a set of ear muffs has a 30 dB rating, it means the noise level of the environment will be reduced by 30 dB when wearing. So if you’re working with a jackhammer that belts out 120 dB of noise, the muffs would reduce that noise to 90 dB, allowing you to spend more time using the tool before any hearing damage occurred.
Keep in mind that there doesn’t necessarily need to be a choice between one and the other. For those who work under extreme noise conditions and do not need to communicate much while working, it is okay to wear both ear plugs and ear muffs at the same time. In doing so, they are ensuring themselves maximum protection from the threat of hearing damage.
When hearing protection is worn, your level of exposure to noise is based on the NRR rating of the protection device being used. Keep in mind, however, that while the NRR is measured in decibels, the hearing protector being used does not reduce the surrounding decibel level by the exact number of decibels associated with that protector’s NRR. For example, if you are at a rock concert where the level of noise exposure is 100 dB and you are wearing earplugs with an NRR 33dB, your level of exposure would not be reduced to 67 dB. Instead, to determine the actual amount of decibel deduction applied (when decibels are measured dBA which is the most common), you take the NRR number (in dB), subtract seven, and then divide by two. Given the previous example, your noise reduction equation would look like the following: (33-7)/2 = 13. This means that if you are at a rock concert with a level of noise exposure at 100 dB and you are wearing a hearing protector with an NRR 33 dB, your new level of noise exposure is 87 dB. If you are wearing a product with an NRR of 27 it would deduct 10 decibels (27-7/2=10).
*To maximize noise reduction, hearing protectors must be worn properly.
When hearing protectors are worn in combination (i.e. earplugs AND earmuffs), rather than adding the two NRR numbers together, you simply add five more decibels of protection to the device with the higher NRR. For example, using (NRR 29) Earplug with (NRR 27) Earmuff would provide a Noise Reduction Rating of approximately 34 decibels.
Noise Reduction Rating (NRR) is a unit of measurement used to determine the effectiveness of hearing protection devices to decrease sound exposure within a given working environment. Classified by their potential to reduce noise in decibels (dB), a term used to categorize the power or density of sound, hearing protectors must be tested and approved by the American National Standards (ANSI) in accordance with the Occupational Safety & Health Administration (OSHA). The higher the NRR number associated with a hearing protector, the greater the potential for noise reduction.
While the amount of on-the-job noise exposure can be determined through various testing devices, excessive noise is generally defined as exposure to 85 or more decibels of sound over an 8 hour period.According to OSHA,hearing protection is required for all employees at this degree of exposure. This OSHA Action Level, however, will vary depending upon the decibel level of the surrounding environment. For example, if a worker is exposed to 100dB in a 2 hour period, he or she is also required to wear hearing protection. Each hearing protector product is required to meet the ANSI S3.19-1974 testing of NRR levels.
In all cases where the sound levels exceed the values shown below, a continuing, effective hearing conservation program should be administered.
For a better grasp of industry standards, here are a few of the most common producers of noise levels that OSHA considersto be dangerous: lawnmowers, rock concerts, firearms, firecrackers, headset listening systems, motorcycles, tractors, power tools and industrial machinery. The use of hearing protection is strongly recommended during continued exposure to any of the previously listed environments, as all can deliver sounds in excess of 90 decibels.
Painful:
150 dB = Rock Concerts at Peak
140 dB = Firearms, Air-Raid Siren, Jet Engine
130 dB = Jackhammer
120 dB = Jet Plane Take-off, Amplified Music at 4-6 ft., Car Stereo, Band Practice
Extremely loud:
110 dB = Machinery, Model Airplanes
100 dB = Snowmobile, Chain saw, Pneumatic Drill
90 dB = Lawnmower, Shop Tools, Truck Traffic, Subway
Very loud:
80 dB = Alarm Clock, Busy Street
70 dB = Vacuum Cleaner
60 dB = Conversation, Dishwasher
Moderate:
50 dB = Moderate Rainfall
40 dB = Quiet room
Faint:
30 dB = Whisper, Quiet Library
Exposing yourself to high decibel environments can result in permanent damage to your hearing. In the event you find yourself in one of these environments, protect yourself with the proper hearing protection. If you have questions about any of the hearing protection products on our website, please feel free to call our customer service department. Our staff is dedicated to keeping your hearing safe and sound.
How 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.