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由于工业和交通运输事业的发展,噪声问题日益严重。在工业中噪声的主要危害是造成噪声性耳聋,据估计,美国约有5～8百万人因直接和间接在噪声环境下工作而造成噪声性耳聋。城市公共交通运输的噪声影响面则更大,在美国,大约有6千万人暴露在机动车辆噪声污染范围内,声级超过 ISO 推荐标准。美国现在有乘用车辆超过9千万辆,大型车辆1千8百万辆以上。在美国,大型车辆有40％的车哩数(每个载重车行驶一哩)是运行于城市街道,从而给城市带来严重的噪声污
Due to the development of industry and transportation, the noise problem is worsening day by day. The major hazard of noise in industry is noise-induced deafness, which is estimated to cause noise-induced deafness in the United States by about 5-8 million people working directly and indirectly in noisy environments. The noise impact of urban public transport is even greater. In the United States, about 60 million people are exposed to noise pollution from motor vehicles and sound levels exceed the ISO recommended standards. The United States now has over 90 million passenger vehicles and over 18 million large vehicles. In the United States, 40% of large vehicles (one mile per truck) run on city streets, causing serious noise pollution to the city