Personal attenuation ratings reported using Fit Check Solo™: Is background noise a concern?

It is well known that some personnel, especially Service Members, operate in hazardous noise-environments. To reduce the risk of hearing loss and hearing related disabilities, hearing protection devices (HPDs) are worn to decrease the level of noise at the ear. Noise attenuation provided by HPDs can vary greatly depending on user fit. Fit test systems were developed to measure the noise attenuation performance of HPDs and to report a personal attenuation rating (PAR) based on that particular fit. Elevated levels of background noise in a typical office-type setting (in comparison to a laboratory) could however affect PAR results. A study completed by the Air Force Research Laboratory compared PAR results of 3M EAR Classic earplugs and Howard Leight Airsoft earplugs from data collected using ANSI S12.6 methodology in the laboratory and data collected using Fit-Check Solo™ in an office environment, a controlled noise office environment, and the laboratory. Results demonstrated that PARs were affected by increased background noise; however, the significance varied based on the number of frequencies used in the PAR calculation. Experimental methodologies, PAR results, and background noise levels will be presented.