Introduction of European EN 352 standards, Requirements for Hearing Protection Devices

【Abstract】 Noise-induced hearing loss and its prevention get more and more attention globally. Among the global standards, the European standards for hearing protection devices (HPDs) has been established as a multi-level system, aligned with ISO acoustics standards. The EN 352 series product standards are extensible to cover products with different functions in addition to passive attenuation. The Part 1-3 of EN 352 provide comprehensive requirements for HPDs on reliability, safety and attenuation, stipulate the manners of labeling and marking for products those are intended to use for occupational protection against noise, prevent the use of products those are not designed for personal protection for occupational protection. In this paper, overview of global HPD product standards and the current European HPD product standards were introduced and discussed, the major content of Part 1~3 of EN 352 were highlighted in the introduction and discussion. 【Keywords】noise-induced hearing loss; hearing protection devices (HPDs); product standard; european standard

0 Preface
Hearing protector is a personal device that protects hearing from overstimulation by noise.Personal protective equipment. As a kind of Personal Protection Equipment (PPE), product standards and selection guidelines for hearing protectors have also attracted a lot of attention. In my country, mandatory product standards have not yet been established, and the national standards related to hearing protectors are shown in Table 1. Absorbing advanced experience at home and abroad, establishing hearing protector standards and building a hearing protector standard system is an important basis for standardizing product performance and ensuring workers’ hearing health, and it is imperative.

1 Overview of foreign hearing protector product standards
The ISO standard for hearing protectors is under the jurisdiction of the ISO/TC43 Acoustic Standardization Technical Committee. At present, only the acoustic test method standard has been established, and the product technical requirements are not specified. Most of the countries and regions that have established product standards are in Europe, North America, Australia and the United States. Brazil, including passive sound attenuation performance nominal values ​​and test methods (see Table 2 for a summary). As can be seen from Table 2, European and American standards are widely used. American standards ANSI S3.19 and ANSI S12.6 are both acoustic test methods, and no separate product standards are established. Weighing for testing, it has not been updated so far, and the old version from 1974 is still used legally. ANSI S3.19-1974 has actually been replaced by ANSI S12.6, the latest version was released in 2016, in which Method B uses inexperienced subjects to test sound attenuation, which was adopted by Brazil [1-2]. use. Canada accepts both ANSI S3.19 and ANSI S12.6 Method B, which means that ANSI S3.19 nominal values ​​are more common in North America. The Australian/New Zealand standards are formulated with reference to European and American standards, rather than directly adopting them. The test methods of inexperienced subjects are used. The physical performance requirements are balanced between European and American standards, and additional requirements are added according to local special conditions.

Testing products with inexperienced subjects in the hope that the results of laboratory tests will be closer to reality brings new problems. The sound attenuation test relies on the subject’s auditory judgment. The variability of this subjective test method is difficult to control. If the subject has no wearing experience, the variability will further increase, and it will be more difficult between laboratories. Comparing with each other and constantly recruiting new inexperienced subjects is challenging. Therefore, this method is widely used and is currently only used in Brazil and Australia/New Zealand.
The criteria presented above are only applicable to the evaluation of passive sound attenuation performance of hearing protectors. If the product has additional functions that depend on the circuit, the test is only carried out with the additional functions turned off, and does not include the evaluation of the additional functions, while the European standard can be fully evaluated.
The product standards and test method standards in the European standard system are formulated separately, and the test methods include physical performance and acoustic tests respectively. The acoustic test method applies the ISO acoustic standards, and also cites some ISO electro-acoustic test technical standards. In this way, relying on a large number of standardized test methods, the hearing protector standard system presents from product standards to test method requirements to basic test technical standards. Multi-level features, which are independent of each other, and refer to each other in layers, are also very complex, but they can achieve flexible responses to market and technological changes, and add applicable standards at any time as needed, which can solve those additional problems of hearing protectors. The problem of electroacoustic performance evaluation when the function is turned on. On the passive sound attenuation nominal, the European standard refers to the ISO part of the acoustic standard. 8-10 As ISO standards are widely recognized and adopted, European standards have naturally become an important reference for many countries. For example, South Korea is formulating its hearing protector product standards with reference to European standards, and Japan is also formulating its own hearing protector test methods with reference to ISO standards. standard. The content of the standard and its implementation will also be more complete. A comprehensive understanding of the trends of European hearing protector regulations and standards can provide a very valuable reference for the construction of my country’s hearing protector standard system.