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
14
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
Whatwasthenewkindofpowerintheearly1800s?Itwas_______________________
职业病防治的法律制度主要规定下列哪个部门应履行相应的义务A.用人单位 B.监督
患者戴全口义齿后1周复诊,诉牙床疼痛无法戴用,检查发现下颌后牙区牙槽嵴顶部黏膜较
肢体被动运动的目的不包括A.促进血液循环 B.恢复肌肉功能 C.预防静脉血栓
2013年二季度,我国税收月收入同比增速逐步提高,分别为7.9%、8.3%和12
各种运输方式内外部的各个方面的构成和联系,就是( )。 A.运输系统
在个人客户信用风险监测与预警示例中属于行内风险预警的有()。A.个人在本行
玄参的主治病证有A.咽喉肿痛 B.温热病热入营分 C.痈肿疮毒 D.瘰疬痰
(2020年真题)在其他因素不变的条件下,总供给曲线反映的是总供给与()
近来,某公司的人力资源部对同行业的员工福利状况进行了一次调查。调查显示:就每个月
最新回复
(
0
)