Field Attenuation Study Shows Individual Training Key To Hearing Protector Effectiveness

-- Study by Howard Leight Acoustical Laboratory evaluates factors affecting earplug performance

-- Shows one-third of workers achieve higher attenuation than published NRRs

Smithfield, RI -- A recent field attenuation study conducted by the Howard Leight Acoustical Laboratory on the performance of hearing protection devices showed that individual, one-on-one training was the most significant factor in predicting good earplug performance. The study, which was conducted on over 100 workers at eight different facilities, showed that fully one third of workers achieve attenuation higher than published Noise Reduction Ratings (NRR) for their earplugs, and that another third achieve attenuation within 5 dB of those ratings. Only the remaining third had attenuation that was more than 5 dB below published NRRs.

"This reinforces the need for individual fit testing of earplugs, especially in light of the Environmental Protection Agency's proposed labeling changes," said Brad Witt, MA, CCC-A, Director of Hearing Conservation for Sperian Hearing Protection, LLC, and a principal author of the study. "No generalized rating scheme for hearing protectors can be effective without knowing how much attenuation individual workers actually attain. If a safety manager were to supply earplugs based on the assumption that all
earplugs only achieve half of their published NRR in the field, then clearly two-thirds of the workers in this study would be seriously overprotected, since they are achieving much higher protection than 50%."

In this study, workers were tested during their standard work shifts. They were not pre-screened, and were tested with their own earplugs that they routinely wear on the job, with no modifications. The tested earplugs were from four different hearing protection device manufacturers, and workers received no training or coaching as part of the test. The workers were simply asked to insert the earplugs as they normally did
on the job. No feedback or correction was offered if they fit the earplug incorrectly.

According to Witt, the purpose of the study was to identify factors which contributed to good earplug fit, and hence, good attenuation in use. "A variety of personal as well as program factors were evaluated to determine which factors would correlate the best to a good earplug fit among these 100 workers," he said.

Factors evaluated included: gender; age; years working in a hazardous noise environment; ear canal size; familiarity with hearing protection devices; model of product used; amount of group training received; amount of individual training received; and enforcement.

Of all these factors, said Witt, "only one stood out as having a strong correlation: one-on-one training. That is, the more often a worker had received Individual Training in the proper use of hearing protectors, the higher the probability of a good fit." The same could not be said for Group Training, according to Witt. "It appeared to make no difference at all whether a worker had attended zero, five or ten group training
sessions in hearing protection, when measuring good attenuation in the field."

Enforcement, he added, was also a good predictor of good earplug performance, but only when it was coupled with one-on-one training.

Another question posed by the study was whether workers who achieved low attenuation with one type of earplug would also attain low attenuation with all types of earplugs. "We tested this by inviting some workers to try a second pair of earplugs-different earplugs, perhaps a model they had never tried before," said Witt. Workers who tried a second pair of earplugs often had major leaps in attenuation, bringing them
closer to the published NRR.

"Field testing of hearing protectors bridges the gap between the laboratory estimates of attenuation and the real-world attenuation achieved by workers as they normally wear the protectors," Witt concluded. "This test confirmed the value of individual, one-on-one training, and the wisdom of offering workers a variety of
suitable hearing protectors."

Since its beginnings as a one-man operation more than 30 years ago, Howard Leight by Sperian has grown into one of the largest global manufacturers of hearing protectors in the industrial market and the recognized innovator in protection and people-oriented fit. Howard Leight offers the widest variety of hearing protection devices and technology, ranging from the highest attenuating Max® single-use earplug,
to SmartFit® earplugs with Conforming Material Technology(TM)-which delivers a more personalized fit-to VeriPRO(TM), the new industry-changing fit verification system for hearing protectors. Utilizing Bilsom® Technology, Howard Leight earmuffs raise the bar on innovative design, performance and comfort, with features like padded wire headbands, high-visibility designs, unique sound management technologies and
multi-level attenuation options. Visit Howard Leight online at

With nearly 6000 employees worldwide, Sperian Protection is resolutely geared towards international markets. The world leader in personal protective equipment (hearing, eye, respiratory and fall protection, gloves, clothing and footwear), the Group offers innovative products adapted to high-risk environments so that all workers in the manufacturing and services industries can work with confidence. Sperian Protection
is listed on Euronext's Eurolist and on the SBF120.

Media Contact:


Thomas R. Rankin, APR


For additional information, contact:

Sperian Hearing Protection, LLC

7828 Waterville Road

San Diego, CA 92154

Tel: 800-430-5490

Fax: 401-232-3110


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