Guide to Hearing Protection
Many occupations expose workers to harmful noise levels. Hearing protectors, such as ear plugs and ear muffs, can greatly reduce the damaging effects of constant noise exposure. There are many styles of hearing protection, and each type has its own benefits. Check out PE Facts to find out which form of hearing protection is right for you!
In the U.S. today, there is an estimated 30 million people exposed to harmful noise levels at work. Hearing protectors are a simple solution that minimizes the hazardous effects of working in a noisy environment. Several questions that should be considered before selecting a hearing protector for use in your facility include:
- Are we required to provide hearing protection?
- Does the hearing protector provide adequate noise reduction?
- What types of hearing protectors are available?
- Is the hearing protector compatible with any other Personal Protective Equipment (PPE) we are using?
This document will tackle these issues and offer guidelines for choosing hearing protectors that are most appropriate for your application.
Regulations
Regarding the use of hearing protectors, the Occupational Noise Exposure Standard - 29 CFR 1910.95 Section (i ) states:
"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…."
It goes on to state that employers must provide various types of hearing protectors for employees to choose from. They are also required to train employees to use and maintain the hearing protectors as well as enforce the wearing of hearing protectors by all employees that meet the standard requirements.
Noise Reduction Rating
The Noise Reduction Rating (NRR) is the maximum number of decibels (dB) that will be reduced when the hearing protector is worn. According to Section (j) of 1910.95, hearing protectors should have an NRR adequate enough to reduce the employee’s exposure to a Time Weighted Average (TWA) of 90 dB (decibels) (or 85 dB for employees who have had a significant threshold shift).Appendix B of the same standard also states some correction factors when using the NRR to judge the effectiveness of the hearing protector.
- If using a C-weighted TWA, subtract the NRR from the TWA to determine the attenuated noise level. (i.e. TWA[C] – NRR = Attenuated Noise Level).*
- If using an A-weighted TWA, first subtract 7dB from the NRR, and then subtract the remainder from the TWA to determine the attenuated noise level. (i.e. A weighted TWA[A] – (NRR-7db) = Attenuated Noise Level).*
OSHA also recommends reducing the NRR by an additional safety factor of 50%, however, this is only a suggestion and it cannot be enforced.
Types of Hearing Protectors
There are many different types of hearing protectors available, offering various advantages and disadvantages. The most common types are:
Disposable Earplugs : These are the most common type of hearing protector. They are typically made of a PVC (polyvinyl chloride) or PU (polyurethane) foam. Disposable earplugs work by being compressed or rolled-down before inserting them. Once in, they slowly re-expand to fill the ear canal. These earplugs may come equipped with or without a pre-attached cord and they are generally one-size-fit-all (some sized plugs may also be available). These types of earplugs are intended for one use only; they are not designed to be cleaned or reused.
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| Figure 1. |
Reusable Earplugs: This type of earplug is made of a flexible material (such as silicone) that is molded to fit the ear canal. They are able to be cleaned with soap and water so that they can be reused. They may come with or with out a cord. They are more durable than disposable earplugs but they usually have a lower NRR. Reusable and disposable earplugs are both small enough to be worn simultaneously with other head/face/eye protective equipment such as hard hats, face shields or safety glasses.
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| Figure 2. |
Hearing Bands: Hearing Bands are a flexible band with earplugs attached to the ends, which can be worn in numerous ways such as over-the-head, under-the chin or behind the neck. The band also allows it to hang around the neck when not being used. The NRR of hearing bands is comparable to most other earplugs. It can be used with most other equipment such as hardhats, face shields or glasses, depending on the position of the band.
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| Figure 3. |
Earmuffs: Earmuffs consist of rigid cups lined with soft cushions that seal around the ears to block noise. Generally, the higher the NRR, the bulkier the earmuff cups tend to be (larger cups with more sound reducing insulation). Earmuffs are typically made of all plastic materials. These are called dielectric and are perfect when working under potentially hazardous electrical conditions. Sometimes a combination of plastic and metal materials is used for stronger durability. The three most popular designs for earmuffs are over-the-head (see Figure 4a.), cap-mounted (Figure 4b.) and behind-the-neck (Figure 4c.). The cap-mounted earmuffs are intended to attach directly to most hard hats with side-accessory slots. The behind-the-neck style can also be worn with a hard hat or face shield.
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| Figure 4a. | Figure 4b. | Figure 4c. |
Electronic Earmuffs: These are essentially the same as standard earmuffs but they also have other features such as AM/FM radio reception, two-way radio reception or amplification of low sound levels.
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| Figure 5. |
Commonly Asked Questions
Q. Can earplugs and earmuffs be used together for extra noise reduction?
A. Yes. OSHA does not object to earplugs being worn underneath earmuffs. The NRR this will produce is calculated by adding 5 dB to the NRR of whichever protector (the earplug or the earmuff) has the higher NRR. Remember that this is after the required reduction factor of 7dB (if using the A weighted scale) has been calculated. For example, if you were using an earplug with a NRR of 32dB with an earmuff with 27dB NRR, your noise reduction calculations would be:
- 32dB[A] (earplug) – 7db (OSHA Safety Factor) = 25 dB
- 25 dB + 5 dB (for using earmuff and earplug together) = 30 dB
- Total corrected NRR = 30 dB
Sources for More Information
29 CFR 1910.95, Occupational Noise Exposure
Please Note: The information contained in this publication is intended for general information purposes only. This publication is not a substitute for review of the applicable government regulations and standards, and should not be construed as legal advice or opinion. Readers with specific questions should refer to the cited regulation or consult with an attorney.
