Pardon me?As you get older,you may notice that your hearing is not as sharp as it once was.Although age does affect hearing,hearing loss is most likely to occur because of exposure to constant sounds in one’s daily life.
The American Speech and Hearing Association has estimated that 40 million Americans are affected every day by dangerously high levels of noise.Sound is neasured in decibels(分贝),and studies show that permanent hearing impairment can result from exposure to sound levels of 85 decibels.Many high decibel noises come fron machines,but machines are not the only producers of painfully loud noises.A screaming baby,at 90 decibels,is more damaging to the sensitive inner ear than a vacuum cleaner at 70 decibels,street traffic at 75 decibels,or an alarm clock at 80.Long exposure to the sound of a jackhammer,whose noise level reaches 100 decibels,a power mower (割草机) at 105 decibels,an auto horn at 120 decibels,or a jet engine at 140 decibels can cause permanent damage to a person’s hearing.
Obviously,people such as airplane pilots or construction workers,who are regularly exposed to loud noises should pay attention to protecting their hearing.A survey done,by the New 105 decibels,an auto horn at 120 decibels,or a jet engine at 140 decibels can cause permanent damage to a person’s hearing.
Obviously,people such as airplane pilots or construction workers,who are regularly exposed to loud noises should pay attention to protecting their hearing.A survey done,by the New York League for the Hard of Hearing clearly points up one of these occupational dangers. The study indicates that 50 percent of all rock disc jockeys have suffered from hearing damage,and of these 33 percent have become partially deaf.

您好，或许您一直认为听力大不如前是因为年纪变大，其实年纪或许对听力影响不大，听力多数会因为生常生活中经常处于噪声的环境中而减弱。
据美国言语语言听力协会预计约4千万的美国人每天处于这种高强度有危害的噪声环境中。声音是以分贝来衡量，研究证明处于85分贝强度的噪声环境中会导致永久性听力损害。许多高强度的噪音来自机器，但是机器不是有害噪声制造的唯一来源。一个高达90分贝尖叫婴儿的声音对于敏感的耳膜的危害比起70分贝的真空清洁机、车流产生的75分贝的噪声或者闹钟高达80分贝的声音的更大，处于伦敦的这种环境中，不管是高达100分贝枪声噪声，105分贝割草机运作，120分贝鸣迪声还是140分贝的发动机，都可能引起听力的永久性损害。
显然，经常处于这种环境中的飞行员或者是建筑工人更应该注意保护听力。纽约听证会联盟做的调查清楚的指明了噪声属于职业危险中的一个。调查表明50%的摇滚唱师听力都受到损害，其中的33%已经处于半聋状态。