Hazardous Noise & the Value of Hearing Protection Fit-Testing

Hazardous Noise & the Value of Hearing Protection Fit-Testing

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At the heart of worker protection in any project is ongoing monitoring of the hazards.  Guesstimates of hazardous exposures, or conjecture about the effectiveness of protective equipment, are simply not acceptable in industry.

 

Although hazardous noise is one of the most common and easily identifiable exposures at a worksite, hearing protectors (earplugs and earmuffs) have been evaluated for decades using a guesstimate of effectiveness -- a population estimate of protection.  While this estimate, called the Noise Reduction Rating (NRR), is defined in EPA regulation, it is known to be a poor predictor of how much protection a noise-exposed worker on the jobsite will actually obtain.

 

The reason for this disparity?  The NRR on a package of hearing protectors is defined under ideal test conditions in a laboratory, in which lab personnel (not the test subjects) fit the protectors.  In the lab, the protectors are worn for just a few minutes of testing, while the subject is required to keep the head still, and avoid any jaw or face movements that could adversely affect the fit of the protector.  Following this ANSI-standard test protocol, the results from ten subjects are averaged to generate the NRR.  But it is hardly a good predictor of what is experienced in the real world by individual workers at a worksite.  A hearing protector that is laboratory-labeled to provide 30 decibels (dB) of attenuation (noise-blocking), for example, may provide 32 dB for one worker; but the same earplug may provide 22, 12, or 2 dB of attenuation when fit by other workers in the same setting.

 

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Next: The “lab versus worksite” gap

Blog Author:  Brad Witt  
Blog Catagories:  NRR  noise reduction rating  Hearing Protectors  Hearing Protection  hazardous noise  fit-testing  

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