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
2024-10-06
1
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] How do blind children play soccer?
选项
A、They listen to the sound of the ball bouncing.
B、They ask an adult to guide them.
C、They hold a bell in their hands.
D、They put a bell inside the ball.
答案
D
解析
文章第一段指出“teams of blind children can enjoy fast-moving games of soccer with a bell inside the ball...”因此是put a bell inside the ball。
转载请注明原文地址:https://tihaiku.com/zcyy/3789110.html
相关试题推荐
Steven’sclose______tohisbrothermadepeoplemistakethemforoneanother.A、
Workingunderthenewexpertwhoalwaysencouragescreativityinyoungpeople,w
Howmanypeoplewererescuedfromthedepartmentbuilding?[originaltext]Hun
Whydopeopleplayteamsports?[br][originaltext]Therearetwomainkind
Blindpeopleusuallypossessoneadvantageoverotherpeoplewhocansee:t
Blindpeopleusuallypossessoneadvantageoverotherpeoplewhocansee:t
Blindpeopleusuallypossessoneadvantageoverotherpeoplewhocansee:t
Blindpeopleusuallypossessoneadvantageoverotherpeoplewhocansee:t
______hasrecentlybeendone,toprovidemoreflatsforthepeople,thehousing
Howmanypeoplehavebeenkilledinthebombings?[originaltext]Aseriesof
随机试题
Aresomepeopleborncleverandothersbornstupid?Orisintelligencedevel
ThenationaldayofAustraliais______.A、Jan.26thB、Jan.1stC、Jan.18thD、Jan.
Novels,magazines,andnewspapers—manypeoplereadtheseintheirsparetime
[originaltext]W:MaybeweshouldtakeFrontStreetthismorning.Theradioanno
不属于沥青混合料力学强度构成的是()A.内摩阻力 B.嵌挤力 C.粘聚
以下不属于高危儿的是A.新生儿体重2400g B.手术产儿 C.妊娠36周早
下列哪种方法制备的胶体金是红色A.维生素CB.白磷C.硼氢化钠D.鞣酸E.枸橼酸
在城乡规划编制单位资质管理的变更程序中,城市规划编制单位合并或者分立,应当在批准
性寒,能利尿,清热解暑,化痰软坚,与药物共制可除去药物腥味的炮制辅料是A.河砂
质量保证金总预留比例不得高于工程价款结算总额的()。A.1% B.3% C
最新回复
(
0
)