Suter Alice H
Alice Suter and Associates, Portland, Oregon.
Semin Hear. 2017 Aug;38(3):225-262. doi: 10.1055/s-0037-1603726. Epub 2017 Jul 19.
Noise levels are truly continuous in relatively few occupations, with some degree of intermittency the most common condition. The sound levels of intermittent noise are often referred to as non-Gaussian in that they are not normally distributed in the time domain. In some conditions, intermittent noise affects the ear differently from continuous noise, and it is this assumption that underlies the selection of the 5-dB exchange rate (ER). The scientific and professional communities have debated this assumption over recent decades. This monograph explores the effect of non-Gaussian noise on the auditory system. It begins by summarizing an earlier report by the same author concentrating on the subject of the ER. The conclusions of the earlier report supported the more conservative 3-dB ER with possible adjustments to the permissible exposure limit for certain working conditions. The current document has expanded on the earlier report in light of the relevant research accomplished in the intervening decades. Although some of the animal research has supported the mitigating effect of intermittency, a closer look at many of these studies reveals certain weaknesses, along with the fact that these noise exposures were not usually representative of the conditions under which people actually work. The more recent animal research on complex noise shows that intermittencies do not protect the cochlea and that many of the previous assumptions about the ameliorative effect of intermittencies are no longer valid, lending further support to the 3-dB ER. The neurologic effects of noise on hearing have gained increasing attention in recent years because of improvements in microscopy and immunostaining techniques. Animal experiments showing damage to auditory synapses from noise exposures previously considered harmless may signify the need for a more conservative approach to the assessment of noise-induced hearing loss and consequently the practice of hearing conservation programs.
在相对较少的职业中，噪音水平是真正连续的，某种程度的间歇性才是最常见的情况。间歇性噪音的声级通常被称为非高斯分布，因为它们在时域中不是正态分布的。在某些情况下，间歇性噪音对耳朵的影响与连续性噪音不同，正是基于这一假设才选择了5分贝的交换率（ER）。近几十年来，科学界和专业人士一直在争论这一假设。这本专著探讨了非高斯噪音对听觉系统的影响。它首先总结了同一作者早期关于ER主题的一份报告。早期报告的结论支持更为保守的3分贝ER，并可能根据某些工作条件对允许暴露极限进行调整。鉴于在这几十年间完成的相关研究，本文件在早期报告的基础上进行了扩展。虽然一些动物研究支持间歇性的缓解作用，但仔细研究其中许多研究就会发现某些弱点，以及这些噪音暴露通常不能代表人们实际工作条件这一事实。最近关于复杂噪音的动物研究表明，间歇性并不能保护耳蜗，而且许多以前关于间歇性改善作用的假设已不再有效，这进一步支持了3分贝ER。近年来，由于显微镜和免疫染色技术的改进，噪音对听力的神经学影响越来越受到关注。动物实验表明，以前认为无害的噪音暴露会对听觉突触造成损害，这可能意味着需要采取更保守的方法来评估噪音性听力损失，从而实施听力保护计划。
