首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Modern technology may not have improved the world all that much but it certainly has made life noisier. Unmuffled motorcycles, b
Modern technology may not have improved the world all that much but it certainly has made life noisier. Unmuffled motorcycles, b
admin
2013-11-29
75
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.
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:https://kaotiyun.com/show/6RhO777K
0
考博英语
相关试题推荐
Whilestillcatching-uptomeninsomespheresofmodernlife,womenappeartobewayaheadinatleastoneundesirablecategory.
Although"namingrights"haveproliferatedinAmericanhighereducationforthepastseveraldecades,thephenomenonhasrecentl
Justiceinsocietymustincludebothafairtrialtotheaccusedandtheselectionofanappropriatepunishmentforthoseproven
Theinfluenceofthemoralstandardsofthehomeisevident.Ifthereisnorecognitionofthedifference【B1】______rightand
Honestynolongerseemstobethebestpolicywithtellingofliesbecomingacommonpartofourdailylives.Anewresearchby
IhadvisitedthecapitalbeforealthoughmyfriendArthurhadnot,IfirstvisitedLondonasastudent,reluctantlyreleasedfr
ArecenthistoryoftheChicagomeat-packingindustryanditsworkersexamineshowtheindustrygrewfromitsappearanceinthe
OnecountrythatiscertainoftheeffectoffilmsontourismisAustralia.TheTouristOfficeofQueenslandsaythatCrocodile
Amongthelowestofthejudicialranks,justicesofthepeaceneverthelessfrequentlyexercisejurisdictionoveravarietyofmi
However,attimesthisbalanceinnatureis______,resultinginanumberofpossiblyunforeseeneffects.
随机试题
按照WH0规定,老龄化社会是指一个国家或地区60岁以上的老年人口达到总人口的()。
有关小儿腹腔镜手术,下列哪一项是不正确的
患者女性,75岁,右大腿卵圆窝反复出现圆形已多年,此次因便秘突出包块增大,用力还纳后右下腹持续疼痛,伴呕吐而就医。下腹压痛,反跳痛及肌紧张,叩诊:肝浊音界缩小。肠鸣音减弱。此时对诊断帮助最小的检查是
关于脑神经的叙述。错误的是
A.肝经风热B.眼窝下陷C.目眦赤烂D.水肿E.黄疸白睛黄染为()。
球菌的运动是靠()。
关于软基处理中竖向排水体的说法,正确的有()。
涉及经济合同中的货物买卖合同争议提起诉讼或者促裁的期限为( )。
Howmanytimeshavethedoctorstestedthechildrenforfiveyears?WhichofthefollowingisNOTtrue?
IstillrememberIfellinlovewithfromaveryyoungage,becauseIthoughtitwassuch,a(n)【C1】______language.Fullofstron
最新回复
(
0
)