据加拿大《北部矿工》一九七五年十二月十八日报道:加拿大许多工业车间和装置的作业环境噪声达到使人痛苦的程度。 一般的耳塞使耳朵听不清所有的声音,令人感到头胀,而产生不愉快的副作用。工人也听不到通知或机器的异常声音。耳塞也使耳朵听管内的空气不流通,从而导致头昏和失 According to Canada’s “Northern Miners” reported on December 18, 1975: The ambient noise of many industrial plants and installations in Canada has reached a level of human suffering. General earplugs make the ear can not hear all the sounds, it is a sense of head swelling, and have unpleasant side effects. The workers also did not hear the notice or the unusual sound of the machine. Earplugs also make the ears of the hearing air tube does not flow, resulting in dizziness and loss