Estimation of noise exposure level for subjects wearing hearing protector devices

Abstract

Industrial workers are exposed to noise levels that could damage their hearing. The Field-MIRE (F-MIRE) method has been developed to quantify earplug and earmuff attenuations with two microphones located under and outside of the HPD. This technique has been designed to be used in the field, but does not give a direct access to the noise exposure level, that is, the noise level at the head location without the subject. In this article, we present a combination of the F-MIRE method with a proposed technique to estimate the sound pressure level without subject, in order to quantify both the ambient and protected noise exposure levels and deduce the effects on worker hearing. Several experiments have been conducted on four subjects with three types of earplugs and with five types of earmuffs. First, the best location for the microphone outside of the HPD has been determined. Second, correction factors that need to be applied on the outside microphone measurement to estimate the sound pressure level without subject have been quantified. Finally, the proposed technique has been validated with measurements taken in a simulated workplace.