we know the sounds of cities are loud enough to cause great harm to people's hearing in the u.

s. one person out of twenty has got some hearing loss. and all over the world the situation is getting worse and worse all the time since the noise increases with the population.

with the development of machines, noise has also increased greatly in the 20th century. we live surrounded by loud planes, trucks and electric tools. tv sets and radios add up to 90 or j00 decibels, a certain unit used to measure the loudness of sound. a normal dialogue reaches 55 decibels; a plane goes to 100, and an ordinary train, reaching the station, can be twice as loud as the loudest plane. disco music reaches about 118. at decibels the ear stops hearing sound, and pain starts. how terrible if things go on like this!

噪音污染

眾所周知，在美國(guó)，城市巨大的噪音對(duì)人們的聽力造成了極大的損害。每20個(gè)人中就有一個(gè)有不同程度的聽力損傷。就世界范圍看來，因?yàn)樵胍綦S著人口的不斷增長(zhǎng)，而越來越嚴(yán)重，這種情況也愈發(fā)惡化。

20世紀(jì)，隨著機(jī)械制造業(yè)的發(fā)展，噪音污染也日益加劇。我們生活在震耳欲聾的飛機(jī)、卡車和電器中。 電視和收音機(jī)加起來甚至達(dá)到90至100分貝(分貝：一種測(cè)定聲音

大小的特定單位)。人們普通的對(duì)話是55分貝；飛機(jī)飛行中為100分貝；而一列普通的火車在到站時(shí)音量能夠達(dá)到最嘈雜的飛機(jī)的兩倍；迪斯科音樂更是高達(dá)118分貝。到達(dá)分貝耳朵就會(huì)喪失聽覺，感到痛苦。這樣下去，該是一件多么可怕的事情啊!

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