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
32
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] In paragraph 5 the word "buffs" means______.
选项
A、settlers
B、enthusiasts
C、buyers
D、manufacturers
答案
B
解析
本题的四个选项中,只有B项为正确答案。四个选项单词的意思分别是settler“定居者”;enthusiast“狂热者”;buyer“购买者”;manufacturer“生产者”。
转载请注明原文地址:http://tihaiku.com/zcyy/4040259.html
相关试题推荐
FromtheabacustotheAppleMac,technologyhasconstantlychangedtheway
Moderntechnologymaynothaveimprovedtheworldallthatmuchbutitcerta
Moderntechnologymaynothaveimprovedtheworldallthatmuchbutitcerta
Moderntechnologymaynothaveimprovedtheworldallthatmuchbutitcerta
Anewbiotechnologyprocedurethatcouldbecomecommerciallyavailableinas
Anewbiotechnologyprocedurethatcouldbecomecommerciallyavailableinas
Anewbiotechnologyprocedurethatcouldbecomecommerciallyavailableinas
Anewbiotechnologyprocedurethatcouldbecomecommerciallyavailableinas
Thetechnologyexiststocomplementand______thehumanmind.A、amplifyB、enrich
Nanotechnology,accordingtoitsfans,willjump-startanewindustrialrevo
随机试题
[originaltext]M:Howoldareyou,Read?Thirteen?W:Oh,it’sasecret.Q:How
Here’sanexampleofhowatypicalconversationaboutmoneygoesinmyhouse
Isittrue______thesnowstops,itwillbeashotasinthesummerhere?A、whenB
海昌公司2016年,年长期资本为5000万元,其中,长期借款为1000
A.I1=20AI2=20AI3=20A B.I1=10AI2=20AI3=5
53岁妇女,绝经2年,阴道分泌物增多伴腰痛2个月,偶有少量阴道出血。妇科检查:宫
精明生意人一般具有哪些特点?( )A.通常有多年的企业海外资本运作经验,对银行
有一患者疑有肾动脉血栓形成,应作哪项检查可确诊:A.彩色多普勒B超 B.放
2006年至2011年全年我国农村居民人均纯收入分别为3587元、4140元、4
借款人采取隐瞒事实等不正当手段套取贷款,属于关注类贷款的特征。()
最新回复
(
0
)