Risk assessment for populations wearing hearing protectors

Abstract

The considerations and parameters underlying the assessment of risk of hearing loss for a population wearing personal hearing protective devices (HPD's) are examined. A damage risk function for a protected population is developed, and measures of hearing protector effectiveness are defined. It is noted that the Noise Reduction Rating (NRR) formulation of protector effectiveness cannot be validly used as a population-oriented measure of hearing protector effectiveness. In the population-oriented context, real-ear attenuation values for hearing protectors obtained under user-fit conditions must be used, but the mean value should only be reduced by 1/4 to 1/2 of a standard deviation in order to provide the required statistical confidence. Finally, some numerical examples of hearing protector effectiveness are developed using computer simulation akin to the Monte Carlo method.