Written on Thursday, March 5, 2009
Noise Reduction Rating (NRR) is an attempt to summarize a hearing protector’s performance in a simple manner, by processing all the test data in accordance with an established formula. Since the 1980’s, the NRR rating has been the most widely and most commonly used criteria to measure performance of hearing protection.
The NRR is a single-number rating that is required by law to be shown on the label of each hearing protector sold in the United States. However, this will soon change.
The EPA will soon make an announcement proposing a major revision in hearing protection labeling requirements. Basically, the NRR will change from a single-number rating into a two-number range.
The reason for the change is this: Many workers do not achieve the amount of attenuation from their hearing protectors as indicated on the NRR label. Improper fit or difficulty of use are examples of why this can happen. Years of research confirm that the current NRR labels highly overestimate the amount of attenuation that individuals actually receive in the work place.
The new dual-number rating will consist of high/low values that are based upon the user’s training, experience, and motivation levels in wearing hearing protection. The high NRR value is possible to achieve for 20% of individuals, falling under the “highly trained and motivated users” category. The low NRR value is obtained for 80% of individuals (most of us), who fall under the “individually trained, but not necessarily motivated or highly trained users” category.
For example, instead of seeing NRR 32, you would see an NRR range of 18 – 32. Most of us (80%) would obtain an NRR of 18 from this particular hearing protector, while only 20% of individuals (highly trained and motivated) would be able to achieve the maximum NRR of 32.
For more information and the most recent updates regarding the NRR revision and associated OSHA compliance policies, please visit NRRupdate.com.
Written by Carissa Kelley