Life in the modern world makes it hard for us to avoid noise pollution. Often, environmental sounds are so loud that they become more dangerous than we think. Ten million Americans suffer from noise-induced hearing loss (NIHL). One in six American teenagers suffers from noise-induced hearing disorder. Since hearing problems caused by noise occur gradually and often go unnoticed, we must actively take steps to prevent this silent threat.
How can loud noise damage hearing? Our inner ear has a snail-like structure lined by cells with fine hairs. Loud noise can kill hair cells and harm the hearing nerve. Once the hair cells are destroyed, no current treatment exists to repair them. The result is permanent hearing loss.
NIHL can result from a one-time exposure to a loud sound, like a gunshot or fireworks. It is also caused by repeated exposure to sounds over an extended period. This means listening to music on our phones and MP3 players for a long time and at high levels is unhealthy for our ears.
Even if we avoid fireworks and earphones, everyday urban sounds can also lead to NIHL. Sirens, garbage trucks, jackhammers, and loud music blasting from shops cause havoc on our hearing. At home, vacuum cleaners, blow-dryers, and TVs also produce potentially harmful noises.
生活在現代社會讓我們很難避免噪音汙染。很多時候，周遭環境的聲音十分吵雜，變得比我們認為的更加危險。有一千萬名美國人身受「噪音性聽力損失」之苦。每六個美國青少年就有一個罹患噪音性聽力疾病。由於噪音造成的聽力問題是逐漸產生的，且通常不會被注意到，因此我們必須積極採取行動來預防這個無聲的威脅。
強烈噪音是如何傷害聽力的呢？我們的內耳有一個長得像蝸牛的構造，上頭排列著長了細毛的細胞。強烈的噪音會殺死毛細胞，並損害聽覺神經。一旦毛細胞受損，目前並沒有能修復的治療方法。結果就是永久性的聽力損失。
噪音性聽力損失可能肇因於一次性地暴露在極大的聲響中，例如槍響或爆竹聲。也可能是持續一段時間不斷暴露在噪音中所致。這表示長時間以高音量用手機或MP3播放器聽音樂對耳朵來說是不健康的。
即使我們避開爆竹和耳機，城市裡的日常聲響也可能導致噪音性聽力損失。警報器、垃圾車、手持式鑿岩機和商店傳來的大聲音樂都會對我們的聽力造成極大的損害。在家裡，吸塵器、吹風機和電視也有可能製造有損健康的噪音。
文章出處：Live互動英語雜誌
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