Real-ear attenuation of custom-fit earplugs with the communications earplug (CEP)

Hearing loss is one of the most common occupational injuries in the Department of Defense. Aircrew members are exposed to the continuous noise generated by aircraft and impulsive noise from weapons systems. Even during peacetime, the second most frequent occupational injury for the Armed Services continues to be hearing loss [1]. Pre-formed earplugs do not adequately fit extremely small ear canals, extremely large ear canals, or canals with sharp turns. Custom-fit earplugs may provide a solution for this hard-to-fit population. Fortunately, methodology exists to scan ear impressions to create a digital data set, and transmit this data, via the internet, to a remote manufacturer that will fabricate the custom-fit earplugs. The purpose of this study was to investigate how the attenuation provided by custom-fit earplugs created using the digital scanning technique compared to the attenuation provided by custom-fit earplugs created using the traditional wax-dipped technique when used with the CEP. Results showed that the digitally scanned custom-fit earplugs provide significantly poorer attenuation than the traditional wax-dipped custom-fit earplugs. Comply{trade mark, serif} Canal Tip expandable foam earplugs were also evaluated and the results showed significantly greater attenuation than provided by custom-fit earplugs manufactured by either custom method.