首页
登录
职称英语
Modern technology may not have improved the world all that much but it certa
Modern technology may not have improved the world all that much but it certa
游客
2025-04-16
12
管理
问题
Modern technology may not have improved the world all that much but it certainly has made life noisier. Unmuffled motorcycles, blaring car alarms, and roving boom boxes come first, second, and third on my list of most obnoxious noise offenders, but everyone could come up with his own version of aural hell—if he could just find a quiet spot to ponder the matter.
Yet what technology has done, other technology is now starting to undo, using computer power, to zap those ear-splitting noises into silence. Previously silence-seekers had little recourse except to stay inside, close the windows, and plug their ears. Remedies like these are quaintly termed "passive" systems, because they place physical barriers against the unwanted sound. Now computer technology is producing a far more effective "active" system, which doesn’t just contain, deflect, or mask the noise, but annihilates it electronically.
The system works by countering the offending noise with "anti-noise", a somewhat sinister-sounding term that calls to mind antimatter, black holes, and other Popular Science mindbenders but that actually refers to something quite simple. Just as a wave on a pond is flattened when it merges with a trough that is its exact opposite (or mirror image) , so can a sound wave be negated by meeting its opposite.
This general theory of sound cancellation has been around since the 1930s. In the fifties and sixties it made for a kind of magic trick among laboratory acousticians playing around with the first clunky mainframe computers. The advent of low-cost high-power microprocessors has made active noise-cancellation systems a commercial possibility, and a handful of small electronics firms in the United States and abroad are bringing the first ones onto the silence market.
Silence buffs might be hoping that the noise-canceling apparatus will take the shape of the 44 Magnum wielded by Dirty Harry, but in fact active sound control is not quite that active. The system might more properly be described as reactive, in that it responds to sound waves already headed toward human ears. In the configuration that is usual for such systems microphones detect the noise signal and send it to the system’s microprocessor, which almost instantly models it and creates its inverse for loudspeakers to fire at the original. Because the two sounds occupy the same range of frequencies and tones, the inverse sounds exactly like the noise it is to eliminate: the anti-noise cancelling Beethoven’s Fifth Symphony is heard as Beethoven’s Fifth. The only difference is that every positive pressure produced on the air by the orchestra is matched by a negative pressure produced by the computer, and every negative pressure is matched by a positive, thereby silencing the sound. The system is most effective as a kind of muffler, in which microphones, microprocessor, and loudspeaker are all in a unit encasing the device that produces the sound, stifling it at its source. But it can work as a headset, too, negating the sound at the last moment before it disturbs one’s peace of mind. [br] The writer holds that______.
选项
A、modern technology has disturbed the quiet life of the people
B、modern technology has made people indifferent to noise pollution
C、modern technology has made the present world quieter than before
D、modern technology has failed to solve the problem of noise pollution
答案
A
解析
本题的四个选项中,只有A项为正确答案。这可从文中第一句的“…but it certainly has made life noisier”推知。
转载请注明原文地址:http://tihaiku.com/zcyy/4040257.html
相关试题推荐
FromtheabacustotheAppleMac,technologyhasconstantlychangedtheway
ModernJapan,despiteitsreadyadoptionofwesternmanners,isinthingsth
ModernJapan,despiteitsreadyadoptionofwesternmanners,isinthingsth
ModernJapan,despiteitsreadyadoptionofwesternmanners,isinthingsth
ModernJapan,despiteitsreadyadoptionofwesternmanners,isinthingsth
Moderntechnologymaynothaveimprovedtheworldallthatmuchbutitcerta
Moderntechnologymaynothaveimprovedtheworldallthatmuchbutitcerta
Moderntechnologymaynothaveimprovedtheworldallthatmuchbutitcerta
Moderntechnologymaynothaveimprovedtheworldallthatmuchbutitcerta
Nanotechnology,accordingtoitsfans,willjump-startanewindustrialrevo
随机试题
Youwillhearanotherfiverecordings.Fivespeakersaretalkingaboutproblems
防治支气管哮喘最有效的方法是A.β受体激动药 B.茶碱类药物 C.糖皮质激素
面试中的问题安排应( )A.先易后难 B.先熟悉后生疏 C.循序渐进 D
梁的弯矩图如图示,最大值在B截面,在梁的A、B、C、D四个截面中,剪力为零的截面
如果投资组合A的特雷诺指数高于投资组合B,则一定能够认为A的投资绩效优于B。(
下列灭火剂中,对于钾、钠、铝、镁等物品无效的是( )。A.干粉 B.泡沫
某单位承建一钢厂主干道钢筋混凝土道路工程,道路全长1.2km,红线宽46m,路幅
设计概算的“三级概算”是指( )。 A.建筑工程概算、安装工程概算、设备及工
基带传输在局域网中广泛使用,其优点是()。 A.线路设备简单
甲公司与乙公司签订了一份设备融资租赁合同,乙与甲指定的丙厂商签订设备买卖合同。丙
最新回复
(
0
)