Attenuation performance of double hearing protection devices.

Abstract

High performance jet aircraft are capable of producing 130-150 dB of noise. Large populations work long hours in these high level noise environments and are at risk of hearing loss and related hearing disabilities. An array of hearing protection devices (HPD), both single hearing protection (SHP) and double hearing protection (DHP), are issued to protect aircrew and ground crew members from the nearly constant assault of hazardous noise. American National Standard Institute (ANSI) Methods for Measuring the Real-Ear Attenuation (REAT) of Hearing Protectors S12.6 were used to measure attenuation performance of nearly 20 SHP and DHP configurations. The term DHP can be slightly deceiving. DHP means two devices are worn in combination, not the sum of the attenuation from each device worn singly. The passive attenuation performance of inserts (earplugs) and helmets worn singly and in combination were reported using REAT octave band data, EPA Noise Reduction Ratings (NRR), and ANSI Methods of Estimating Effective A-Weighted Sound Pressure Levels when Hearing Protectors are Worn: the Noise Level Reduction Statistics for use with A-Weighting (NRSA), and the Noise Level Reduction Statistic, Graphical (NRSG).