Nélisse Hugues, Gaudreau Marc-André, Boutin Jérôme, Voix Jérémie, Laville Frédéric
Service de la recherche, Institut de Recherche Robert-Sauvé en Santé et Sécurité au Travail, 505, Boulevard de Maisonneuve Ouest, Montréal, Québec H3A 3C2, Canada.
Ann Occup Hyg. 2012 Mar;56(2):221-32. doi: 10.1093/annhyg/mer087. Epub 2011 Oct 17.
The effectiveness of hearing protection devices (HPDs), when used in workplace conditions, has been shown over the years to be usually lower than the labeled values obtained under well-controlled laboratory conditions. Causes for such discrepancies have been listed and discussed by many authors. This study is an attempt to understand the issues in greater details and quantify some of these factors by looking at the performance of hearing protectors as a function of time during full work shift conditions.
A non-invasive field microphone in the real ear (F-MIRE)-based method has been developed for measuring the effectiveness of different HPDs as a function of time in the workplace. Details of the test procedures, the equipment used, and the post-processing operations are presented and discussed. The methodology was developed in such a way that a complete time and frequency representation are possible. The system was used on a total of 24 workers in eight different companies. Work shifts of up to 9-h long were recorded. Various types of earmuffs and one type of molded earplugs were tested.
Attenuation data reported as a function of time showed, for most workers tested, considerable fluctuations over entire work shift periods. Parts of these fluctuations are attributed to variations in the low-frequency content in the noise (in particular for earmuffs) as well as poor insertion and/or fitting of earplugs. Lower performances than laboratory-based ones were once again observed for most cases tested but also, important left and right ear differences were obtained for many individuals. When reported as a function of frequency, the attenuation results suggested that the few approximations used to relate the measurements to subjective real-ear-attenuation-at-threshold (REAT) data were realistic.
The use of individualized attenuation data and performance ratings for HPDs as well as a good knowledge of the ambient noise in the workplace are key ingredients when evaluating the performance of hearing protectors in field conditions.
多年来的研究表明，听力保护装置（HPD）在工作场所条件下的有效性通常低于在严格控制的实验室条件下获得的标称值。许多作者已经列出并讨论了造成这种差异的原因。本研究旨在更详细地了解这些问题，并通过观察听力保护器在整个工作班次期间的性能随时间的变化来量化其中一些因素。
已开发出一种基于真耳现场麦克风（F-MIRE）的非侵入性方法，用于测量不同HPD在工作场所的有效性随时间的变化。介绍并讨论了测试程序、所用设备以及后处理操作的详细信息。该方法的开发方式使得能够获得完整的时间和频率表示。该系统共应用于8家不同公司的24名工人。记录了长达9小时的工作班次。测试了各种类型的耳罩和一种类型的模制耳塞。
作为时间函数报告的衰减数据显示，对于大多数测试工人，在整个工作班次期间存在相当大的波动。这些波动部分归因于噪声中低频成分的变化（特别是对于耳罩）以及耳塞插入和/或佩戴不当。在大多数测试案例中，再次观察到其性能低于基于实验室的性能，而且，许多个体的左右耳之间存在重要差异。当作为频率函数报告时，衰减结果表明，用于将测量值与主观真耳阈值衰减（REAT）数据相关联的少数近似值是现实的。
在现场条件下评估听力保护器的性能时，使用个性化的衰减数据和性能评级以及对工作场所环境噪声的充分了解是关键因素。
