Abstract
This paper compares dBA levels at the protected ear obtained using the ISO-NIOSH method with the NRR factor recently adopted by the Environmental Protection Agency. The study was done on 144 combinations of 12 noises and 12 protectors. In each case the sound level was predicted using each of the methods. The differences between the levels, E, was used to define the accuracy of the NRR. It was found that the level predicted using the NRR was always higher than measured, the difference ranging between 0 and 11.3 dBA. Because of this rather conservative estimation of the hearing protector's attenuation and the simplicity of its use, the application of the NRR factor in industrial hearing conservation programs is recommended strongly.