Guide to Selecting the Right Ear Muff -- Occupational Health & Safety

Guide to Selecting the Right Ear Muff

When combining hearing protection with safety glasses, face masks, etc., ensure performance is not adversely affected.

Wearing hearing protection can mean the difference between enjoying the sounds of everyday life and a lifetime of disability. Every day, we are exposed to potentially hazardous environmental noise. It is, therefore, critical that workers who must be present where the noise level is high and constant select either a muff or plug protector to reduce the noise level to an acceptable level. We will now discuss the factors you should consider when selecting the correct ear muff for the job.

Step 1: Determining Your Noise Level
Is the noise level and frequency content known (dB and Hz)?

If not, see the list of common noise sources on the next page. On some machines and power tools, you can find the dB level in the user manual or stated on a label on the machine.

If yes, follow this example: It is recommended that the calculated level under the ear muff should be under 85 dB (A). Therefore, subtract 85 dB from the noise level dB to find out the minimum protection level needed. The key is to provide enough attenuation but not enough to overprotect the wearer. Understand your whole-shift noise exposures and select the ear muff on the basis of that exposure, and do not use the highest measured noise level as your guide.

Example:

If you use a chainsaw, and the dB level is 110 dB (A). The recommended level under the ear cup should be below 85 dB (A). Therefore, you need an ear muff with an attenuation of at least 25 dB (110–85 =25).

When to consider selecting an ear muff with a lower protection level:

• Is the exposure time shorter than four hours? The ear muff protection level is based on noise exposure over an eight- hour working day. If the exposure is shorter, you should consider selecting a lower protection level.
• Do you need to hear important information from colleagues, warning signals etc.? Consider selecting a lower protection level or use an electronic level dependent ear muff.
• Are you suffering from hearing loss? If you have a hearing impairment, you may already have difficulty understanding speech in noisy environments. If you select the highest attenuation for hearing protectors, you may find it even more difficult to communicate or hear warning alarms.

When to consider selecting an ear muff with a higher protection level:

• Does the noise consist mainly of low-frequency noise? If the noise is mainly low frequency, you should consider selecting a higher protection level because low-frequency noise is more difficult to block out.
• Do you need to wear safety glasses, face masks etc.? When combining hearing protection with safety glasses, face masks, etc., ensure performance is not adversely affected. If you are uncertain, seek additional advice and guidance or select an ear muff with a slightly higher protection level.
• Are there any other noise sources nearby? If there are other noise sources nearby, you should consider selecting a higher protection level.

This article originally appeared in the June 2015 issue of Occupational Health & Safety.

 

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.

Shop Hearing Protection by Noise Reduction Ratings (NRR)

 

If you are interested in shopping our entire selection of hearing protection you can browse here.

How does NRR change decibels of exposure?

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.

How does wearing dual hearing protectors change NRR?

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 3M™ E-A-R™ Classic Earplugs (NRR 29) with 3M™ Peltor™ H7 Deluxe Earmuffs (NRR 27) would provide a Noise Reduction Rating of approximately 34 decibels.

What is considered excessive noise?

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

Save Your Hearing

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.