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NRR ratings


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So I was debating between buying earplugs or ear muffs. Through a little research, on YouTube and Ebay I found that I should be looking for the highest NRR. The highest I found were by a company called Titus which produces an ear muff of 37 NRR. Anybody have any opinions about earplugs/earmuffs/ noise reduction ratings or the Titus company? :confused: Thanks.

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I use SureFire Pro defenders combined with electronic MSA Sordin Supreme Pro-X with silicone gel ear seals.


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).


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.



Symbol  Definition Where Used


NRR Noise Reduction Rating United States

SNR Single Number Rating European Union

SLC8 Sound Level Conversion Australia/New Zeal



Users should not be concerned when they see several different attenuation ratings on a package.


The difficulty with inter brand comparison is that each rating number is based upon manufacturers employing differing test standards, test frequencies and calculation methods, and any given hearing protector generates different numbers depending on the rating method used. It is not hard to imagine the manufacturer using only the method that allows the highest possible rating for their product.

Edited by benelliwerkes
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