AN IN-EAR NOISE DOSIMETRY METHOD THAT EXCLUDES THE SOUNDS GENERATED BY INDIVIDUALS WEARING EARPLUGS: PRELIMINARY FIELD STUDY

摘要

Every day, hundreds of millions of employees worldwide are exposed to noise levels that are likely to affect their hearing. While noise reduction at the source remains the preferred solution to address the issue of occupational noise, industrial workers are often left with no other option but to wear hearing protection devices (HPD). Unfortunately, the effective protection provided by a given HPD on a given individual depends upon several subject-dependent variables (e.g. earcanal geometry, HPD fitting and wear time). This makes it difficult, with conventional measurement methods, to properly assess the amount of noise an individual receives during a workshift. To overcome this issue, new measurement techniques have been recently developed, such as in-ear noise dosimetry (IEND). IEND may be integrated into HPDs to perform continuous sound pressure measurements under a hearing protector, and hence obtain personal noise exposure assessments accounting for HPD performance. IEND, however, raises questions about the impact of self-generated noise on measurements, as speech or movements (e.g. chewing, walking) from the wearer may significantly affect the sound pressure levels (SPL) measured inside occluded earcanals. As part of this study, an IEND method was developed to perform noise dosimetry measurements under an earplug while excluding the disturbances induced by the wearer. The approach, which was validated in the laboratory using real-ear measurements performed on still human test-subjects, had yet to be tested in real life environments. This paper presents the results obtained on subjects moving in indoor and outdoor urban environments, and provides recommendations about the application of such method in occupational settings.