Personal attenuation ratings versus derated noise reduction ratings for hearing protection devices.

National and international regulatory and consensus standards setting bodies have previously proposed derating hearing protector ratings to provide a better match between ratings determined in a laboratory and the real-world measurements of attenuation for workers. The National Institute for Occupational Safety and Health has proposed a derating scheme that depends upon the type of protector. This paper examines four real-world studies where personal attenuation ratings (PARs) were measured at least twice, before and after an intervention in earplug fitting techniques. Results from these studies indicate that individualized earplug fitting training dramatically improves a worker's achieved PAR value. Additionally, derating schemes fail to accurately predict the majority of achieved PARs. Because hearing protector fit testing systems are now readily available for use in the workplace, personal attenuation ratings provide a better estimate of worker noise exposures and are able to identify those persons who need additional instruction in fitting hearing protection devices.