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Facts About Noise #4

What’s wrong with the Noise Reduction Rating?

That is a tough question you raise! There are too many answers or no answers, depending on how you look at it.

The NRR is only as good as the underlying test data. Currently, the only requirement imposed upon manufacturers is that the products are tested in accordance with ANSI S3.19-1974.
There is no requirement that the tests are carried out by an independent and certified laboratory.
Neither is there any limitation established for how many years a test report will be considered valid.
In addition there is no enforcement mechanism established, and no Government agency is checking the validity of manufacturer’s data. Neither OSHA, NIOSH or EPA has performed a compliance audit check, or forced any less than honest (or should we be polite and call it optimistic?) manufacturer to use honest numbers!
As you might expect there are a number of companies that have used "inaccurate" data in this environment. If your underlying data is either manipulated or just old and outdated, like let’s say a 17 years old test report for a product that has changed dramatically in that time frame.
You might just be using one of the 29 NRR muffs "that really are not". How can you find out? There are two simple solutions if you care to find out. Ask the manufacturer of the brand you are using to provide one of two documents: 1) a certified U.S. test report from an independent laboratory (with NVLAP stamp), documenting the claimed NRR, 2) a certified CE (European) test report performed after July of 1995 when certification became mandatory in Europe. If the European SNR (Single Number Rating) is 3-4 dB higher than the claimed NRR value, you can relax because the NRR is valid. If not, you may not be getting what you are paying for!

Elvex can provide the official NRR and SNR values for most domestic competitors, if you have trouble getting the reports from your current supplier.

Facts About Noise #4

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