Research progress on verification methods on measuring noise attenuation value of hearing protective devices / 中国职业医学

ABSTRACT

At present, the methods for verifying the attenuation of hearing protective devices(HPDs) mainly include real-ear attenuation at threshold(REAT), microphone in real ear(MIRE), and acoustical test fixture(ATF). Among them, the REAT is the gold standard, but its testing requirements are strict and there is a physiological noise masking effect. The test results of MIRE need to be modified by transfer function of the open ear, which has the advantage of convenient operation without being affected by subjective feelings. The ATF method is mainly used to verify the shape and quality of customized HPDs since its artificial ear design cannot truly reflect the real-ear test situation. The HPD fit testing has been well developed and widely applied abroad, which has been proved to be able to accurately verify and effectively improve the attenuation of workers wearing HPDs. However, relevant research and applications have only been carried out in China in recent years. At present, the main problems in the verification of the protective effect of HPDs in China are as follows firstly, the measurement is only limited in attenuation and fail to comprehensively consider the applicability and comfort of the HPDs; secondly, a-weighted sound pressure level is mostly used in noise monitoring in China, while the choice of HPDs is based on C-weighted-sound pressure level. The transition between these two has not been established. Future research should be devoted to solve the above problems and help the use of HPDs in preventing the hearing loss of noise-exposed workers.