What is the best dB rating for ear muffs?

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.

I sometimes attend events with very loud music, e.g. Technoparade (> 110dB next to speakers) and at times need to stop listening the music, without having to move. How can I achieve maximum hearing protection?

Currently I use a combination of:

How can I improve on that? I can't find (mirror) custom-fitted earplugs or earmuffs that offer more than ~30 dB reduction, unless I missed something, otherwise perhaps could I add a third level of protection (if so, what)?

Note, from Noise Reduction Rating (NRR): A Beginner’s Guide (mirror):

The equipment used to protect hearing does not reduce the decibel levels within a given environment by the precise decibel number that is tied to the NRR for that device. For example, a person who is working in a loud occupational environment may be exposed to noise as great as 100 decibels. If an individual is wearing hearing protection equipment with an NRR of about 30 decibels, the noise exposure amount would not be lowered to 70 decibels. Instead, it would be lowered to 88.5 decibels. Take a look at the following steps taken to determine the level of noise exposure after reduction:

1. Subtract seven from the NRR number, which is given in decibels.
2. Divide the result by two.
3. Subtract the result from the original noise exposure level in decibels.

which means using a custom-fitted earplugs with 30 dB reduction and earmuffs with 33 dB Noise Reduction Rating (NRR) doesn't result in the Technoparade music being reduced from 110dB to 53dB (=110-30-33): instead, the music will be heard at a dB higher than 53. One may use some online hearing protection calculator to compute the actual dB reduction given the NRR and speaker dB. Also, note that for most wearers, the NRR identified on the current EPA label significantly overestimates the protection of the hearing protector in the workplace (mirror).