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
44
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
Hesometimesdoes(add)______workonweekendsintheoffice.additional空格处位于谓语动词do
Salestactics,likeadvertising,reflectaspectsofthebasicassumptionsan
请计算
为了进行状态估计,电力系统中独立测量量与状态量个数之间关系是()A.大于等
1、某桥梁板式橡胶支座,其尺寸为600mm×700mm×130mm,对其进行各项
当导游人员接到旅游者的口头投诉时,导游员必须( )。A.主动道歉,酌情赔偿
下列有关高等学校与政府、社会、学生、教师的社会关系性质,说法正确的有()。A
()原则是指合规人员在对业务部门进行核查时,应当坚持统一标准来对违规行为风
下列支出中,可作为长期待摊费用核算的有()。A.固定资产的大修理支出
订立合同的当事人依照有关法律对合同内容进行协商并达成一致意见时的合同状态称为(
最新回复
(
0
)