NRR & the “lab versus worksite” gap

NRR & the “lab versus worksite” gap


In addition to the fact that the Noise Reduction Ratings (NRR), defined in EPA regulation, are simply population estimates, there are numerous other reasons behind the “lab versus worksite” gap, firmly rooted in the world of real human behavior.

They include:

 -- Lack of proper training for workers in the correct insertion of earplugs

 -- Workers choosing to maximize comfort at the expense of noise-blocking

 -- Earplugs that are poorly sized for a given worker (ear canals come in various sizes)

 -- Hearing protectors that don’t conform to the anatomy of a given wearer’s ear


In reviewing these problems of relying upon the NRR to assess a worker’s protection from hazardous noise, numerous studies acknowledge that the disparity between real-world and lab-rated attenuation is more pronounced in earplugs than earmuffs. There is simply more that can go wrong with the fit of an earplug. The insertion may not be deep enough. The diameter of the earplug may not effectively seal the ear canal. Or that particular wearer may have a bend in the ear canal preventing a full-contact fit with the ear canal walls.


The problem is that, in all of these cases, attenuation is significantly degraded.



Next: Fit Testing and Training

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