Closing the Gap Between Real-World Experience & Desired NRR

Closing the Gap Between Real-World Experience & Desired NRR


The value of fit-testing in helping wearers of hearing protectors close the gap between their real-world experience and their desired NRR was made evident in a field attenuation study conducted by the Howard Leight® Acoustical Laboratory. In the study, the real-world attenuation of earplugs worn by 100 noise-exposed workers at eight different noisy companies was measured. Workers wore a variety of earplugs from several different manufacturers.


Of the 100 earplug users, one-third of the tested workers achieved real-world attenuation that was equal to or higher than the published NRR for their respective earplug. The middle third of workers achieved attenuation within 5 decibels below the NRR, and the bottom third of workers showed real-world attenuation anywhere from 5 to 30 decibels below the published NRR for their selected earplug.


These workers were then interviewed to determine which factors correlated the best to a good earplug fit. The results showed there were no personal factors that were accurate predictors of a good fit of an earplug in the field: gender, age, ear canal size, years in noise, and familiarity with earplug model were simply poor predictors of whether a user would achieve good attenuation.


But when program factors were evaluated to predict good earplug fit, there was one factor that proved to be the strongest indicator of high attenuation in the field: If a worker had received one-on-one training in how to properly fit an earplug, there was a high probability that worker would achieve good attenuation from their chosen earplug.


Importantly, this positive effect of training held up only when the training was administered one-on-one.   The same could not be said for group training sessions. In hearing protection, it seemed to make little difference whether the worker had participated in multiple group training sessions. But a single one-on-one training session significantly improved the probability of good fit, and good protection.



Next: Advocates for Fit-Testing


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

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