首页
登录
职称英语
Noise enters our ears as powerful waves of mechanical energy. Scientists mea
Noise enters our ears as powerful waves of mechanical energy. Scientists mea
游客
2023-09-11
69
管理
问题
Noise enters our ears as powerful waves of mechanical energy. Scientists measure sound intensity in decibels (db), with each doubling of energy adding ten decibels. Ordinary conversation measures about 60 db; a child’s scream hits around 90 db. On this logarithmic scale, the scream is potentially 1,000 times more powerful.
Each day, over five million Americans are exposed on the job to at least 90 db, the maximum safe level for an eight-hour period according to the federal Occupational Safety and Health Administration. "This standard isn’t ideal, because noise affects individuals differently," says William Clark of Washington University’s Central Institute for the Deaf in St. Louis. "In theory, the standard should protect the lifetime hearing ofg0 percent of workers. However, it assumes that a worker’s ears will have 16 hours of quiet each day during which to recover -- an unlikely assumption for most people."
Sound causes thousands of tiny hairs in the inner ear to vibrate. These vibrations trigger nerve impulses to the brain, which are perceived as sound. Prolonged exposure to 85 db or more, or far shorter exposure to very intense levels -- such as the 140-db shock waves from a shotgun blast -- can irrevocably damage some of these delicate inner-ear hairs. Ronald Reagan suffered permanent injury during his acting days when a 38-caliber pistol loaded with blanks was fired near his right ear. As a result, he now wears a hearing aid. Audiologists predict that by the year 2000, as many people could be wearing hearing aids as now wear contact lenses.
Many people believe that weaker hearing is an inevitable part of aging. But studies show that those who live in low-noise environments tend to have very little hearing loss in old age.
In noisy industrial nations, however, even young people suffer damaged hearing. David Lipscomb, a former professor of audiology at the University of Tennessee at Knoxville, tested over a thousand incoming freshmen and discovered that six of every ten had heating loss typical of the elderly. Rock music is one cause. The noise in a reek-concert hall can easily exceed 120 db, roughly the level of an air-raid siren. High-tech gadgets such as powerful portable stereos also threaten to put our hearing into a downward spiral. [br] Scientists think that by the year 2000, _______.
选项
A、people will generally improve their hearing
B、people will have worse hearing
C、people will wear contact lenses and hearing aids as well
D、people wearing hearing aids will outnumber those wearing contact lenses
答案
B
解析
第三段末尾说“到2000年,戴助听器的人将和现在戴隐形眼镜的人一样多。”可见那时人们的听力将会更差。
转载请注明原文地址:https://tihaiku.com/zcyy/3005149.html
相关试题推荐
Povertyexistsbecauseoursocietyisanunequalone,andtherearepowerful
Povertyexistsbecauseoursocietyisanunequalone,andtherearepowerful
Povertyexistsbecauseoursocietyisanunequalone,andtherearepowerful
Povertyexistsbecauseoursocietyisanunequalone,andtherearepowerful
Scientistswillhaveto______________(提出提高世界粮食供应量的新方法).comeupwithnewmetho
Noiseentersourearsaspowerfulwavesofmechanicalenergy.Scientistsmea
Noiseentersourearsaspowerfulwavesofmechanicalenergy.Scientistsmea
Noiseentersourearsaspowerfulwavesofmechanicalenergy.Scientistsmea
Themoretimescientistsspenddesigningcomputers,themoretheymarvelat
Themoretimescientistsspenddesigningcomputers,themoretheymarvelat
随机试题
简要说明意志与情绪过程的关系。
()是指在工程项目实施过程中由于设计、施工技术等方面上的失误而造成的事故。A.
2018年6月,A企业吸收合并B企业,B企业全部资产公允价值为5700万元、全部
根据《民法典》,合同的内容包括()。A.违约责任 B.当事人的名称或者姓名
罗马数字是阿拉伯数字传入欧洲之前欧洲所使用的一种计数符号,共有7个基本符号,采用
某学校为迎接五十年校庆。进行校舍翻新,在此期间依然要求学生正常上课。小田课间休息
全面风险管理就是一个从企业战略目标制定到目标实现的风险管理过程。()
企业在确定当期所得税时,应当在会计利润的基础上,按照适用税收法规的要求进行调整,
纵向围堰堰顶高程,要与束窄河段宣泄导流设计流量时的水面曲线相适应。因此( )。
老年女性,5天前,因“胃肠炎”在当地门诊应用庆大霉素32万U/d治疗,近日来尿量
最新回复
(
0
)