首页
登录
职称英语
Blind people usually possess one advantage over other people who can see: t
Blind people usually possess one advantage over other people who can see: t
游客
2023-11-10
40
管理
问题
Blind people usually possess one advantage over other people who can see: their sense of hearing is far more acute. Sounds which most others would miss can carry a great deal of information to a sightless person. For instance, teams of blind children can enjoy fast-moving games of soccer with a bell inside the ball and a new hand-held ultrasonic device to guide them. And that sound-location system could help to build up an even more complete sound picture of a blind per-son’s surroundings.
Bats, whose sight is poor, use a sound-location system to help them avoid obstacles in the dark. They send out pulses of sound waves, pitched at 50,000 cycles per second, far above the limits of the human ear, which can hear sounds up to frequencies of about 20,000 cycles per second. As the echoes bounce back off obstacles such as trees and walls, the bats are able to take appropriate action.
The first steps to help blind people to see with sound are based on exactly the same principle. The sound is emitted by an ultrasonic torch, shaped like a double-barreled version of a normal electric torch. It works in a similar way to a sonar unit on a warship or submarine.
The unit’s transmitter sends out pulses of ultrasonic waves at the same frequency as the bat, and the receiver picks up the returning echoes. Because these are still above the frequency at which the human ear can pick them up, the echoes are filtered through circuits which turn them into clearly audible bleeps before passing them into headphones.
This means that a person holding the torch can point it ahead of him and scan the area for obstacles over a range of a-bout 25 ft. If there are no return echoes coming through the headphones, then there is nothing in the way.
If echoes do come back, then the closer the obstruction, the faster the succession of bleeps and the deeper the pitch of each bleep. With practice the torch could help a blind person to lead a more normal life——without needing a constant companion to guide him. Experienced operators of the torch system claim they can distinguish grass from bushes, trees, pests and curbstones.
But before blind people can be helped to feel really independent, the system needs to be more streamlined. At present, the experimental ultrasonic torch requires a shoulder bag to carry the batteries, cables for the power supplies and earphones, in addition to the torch itself. But miniaturization of electronic equipment is making such rapid progress that it should not be long before the whole set-up can be reproduced in a form small enough to fit into a pair of spectacles.
The transmitter and power supplies, with all the circuitry, would be packed into the bridge-piece above the nose. The sending and receiving sensors would be in the ’lenses’. And the filtered bleeps would be passed on to the wearer through the earpieces, as with present-day hearing-aid spectacles.
This would mean that scanning one’s surroundings would become instinctive. The wearer would face in the direction he wanted to check, and lift or lower his head just as a sighted person would. [br] Which of the following is NOT true about the ultrasonic torch?
选项
A、It enables the blind to live a more normal life.
B、It is mainly used to scan the area in front of the operator for obstacles.
C、Fast succession of bleeps indicates that the obstacle is near.
D、Its sound can warn other people of the blind man’s approach.
答案
D
解析
A项可从倒数第四段“the torch could help a blind people to lead a normal life”得到根据;B项可从倒数第五段“a person holding the torch can point it ahead of him and scan...”得到证实;C项可从倒数第四段“the closer the obstruction,the faster the succession of bleeps”得到证实;只有D项无出处。
转载请注明原文地址:https://tihaiku.com/zcyy/3174549.html
相关试题推荐
Howmanypeoplearesaidtobeinjuredintheaccidentaltogether?[br][origin
Howmanypeoplearesaidtobeinjuredintheaccidentaltogether?[originaltext
Howmanypeoplewerehomelessduetotheearthquakeandtsunami?[br][original
OnJanuary1stmanypeoplemakeaNewYear______.A、intentionB、determinationC、d
Manyelderlypeoplearesufferingfromthe______disease,rheumatism,asacons
Ithinkmostpeoplewouldagreethattomanloveis______.nutritionistoplant
ThepeopleatthepartywereworriedaboutSusanbecausenoonewasaware______
Therewasatimeinmylifewhenpeopleasked【C1】______forstoriesaboutwha
Therewasatimeinmylifewhenpeopleasked【C1】______forstoriesaboutwha
Therewasatimeinmylifewhenpeopleasked【C1】______forstoriesaboutwha
随机试题
[originaltext]M:Excuseme,mayIcomein?W:Ohyes.HowcanIhelpyou?M:I
Thepresidentandhisadvisorsdiscussedmattersthat______tothewar.A、attain
依据土的颗粒组成特征,土的塑性指标平和有机质含量,路基用土可分为()。A.粗粒
江海大学的校园美食节开幕了,某女生宿舍有5人积极报名参加此项活动,她们的姓名分别
水位流量关系曲线高水位部分延长常用方法不包括()。A.利用水位面积、水位流速
以下()不属于沟通与协调原则中的内容A.目标一致 B.信息共享 C.携手共
某省民政厅为了制定本省医疗改革方案,需要对本省的医疗机构和就医人员情况进行调查。
2016年全国餐饮收入35799亿元,同比增长10.8%,餐饮收入占社会消费品零
三羧酸循环主要是在亚细胞器的哪个部位进行的? A.细胞核B.胞液C.
2003年11月20日,某基金管理者持有2000万美元的美国政府债券,他担心市场
最新回复
(
0
)