National Institute for Occupational Safety and Health, Hearing Loss Prevention Team, Cincinnati, Ohio 45226, USA.
Int J Audiol. 2012 Feb;51 Suppl 1(0 1):S31-42. doi: 10.3109/14992027.2011.630330. Epub 2011 Dec 19.
In 2009, the U.S. Environmental Protection Agency (EPA) proposed an impulse noise reduction rating (NRR) for hearing protection devices based upon the impulse peak insertion loss (IPIL) methods in the ANSI S12.42-2010 standard. This study tests the ANSI S12.42 methods with a range of hearing protection devices measured in field conditions.
The method utilizes an acoustic test fixture and three ranges for impulse levels: 130-134, 148-152, and 166-170 dB peak SPL. For this study, four different models of hearing protectors were tested: Bilsom 707 Impact II electronic earmuff, E·A·R Pod Express, E·A·R Combat Arms version 4, and the Etymotic Research, Inc. Electronic BlastPLG™ EB1.
Five samples of each protector were fitted on the fixture or inserted in the fixture's ear canal five times for each impulse level. Impulses were generated by a 0.223 caliber rifle.
The average IPILs increased with peak pressure and ranged between 20 and 38 dB. For some protectors, significant differences were observed across protector examples of the same model, and across insertions.
The EPA's proposed methods provide consistent and reproducible results. The proposed impulse NRR rating should utilize the minimum and maximum protection percentiles as determined by the ANSI S12.42-2010 methods.
2009 年，美国环境保护署（EPA）根据 ANSI S12.42-2010 标准中的脉冲峰值插入损耗（IPIL）方法，提出了一种基于脉冲噪声降低等级（NRR）的听力保护装置。本研究采用 ANSI S12.42 方法，在现场条件下对一系列听力保护装置进行了测试。
该方法利用声学测试夹具和三个脉冲水平范围：130-134、148-152 和 166-170dB 峰值 SPL。在这项研究中，测试了四种不同型号的听力保护器：Bilsom 707 Impact II 电子耳罩、E·A·R Pod Express、E·A·R Combat Arms 版本 4 和 Etymotic Research，Inc. Electronic BlastPLG™ EB1。
每个保护器的五个样本都安装在夹具上，或在夹具的耳道中插入五次，每个脉冲水平进行五次插入。脉冲由 0.223 口径的步枪产生。
平均 IPIL 随峰值压力而增加，范围在 20 到 38dB 之间。对于一些保护器，同一型号的保护器样本之间以及插入之间存在显著差异。
EPA 提出的方法提供了一致和可重复的结果。拟议的脉冲 NRR 等级应利用 ANSI S12.42-2010 方法确定的最小和最大保护百分位数。
