Session 1pNSa: Advanced Hearing Protection and Methods of Measurement II 1pNSa9. Estimation of noise exposure level for subjects wearing hearing protector devices

Industrial workers are exposed to noise levels that could damage their hearing. The FieldMIRE (FMIRE) 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 doesn't 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 FMIRE 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. Firstly, the best location for the microphone outside of the HPD has been determined. Secondly, 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.