For centuries, canes have served blind and partially sighted people well by giving them a means to negotiate the world around th

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问题     For centuries, canes have served blind and partially sighted people well by giving them a means to negotiate the world around them. The only serious upgrade they have undergone dates back to 1921, when a Briton called James Biggs, who had recently lost his sight, painted his own cane white in order to make it easily visible and to alert others to the presence of someone unable to see nearby obstacles. In the opinion of Daniela Rus of MIT, however, the white cane has had its day. Dr. Rus would like to replace it with a system that scans its user’s environment and communicates back to him what it sees.
    Dr. Rus’s device consists of a camera worn on a string around the neck, and a belt. A computer inside the camera creates a three-dimensional image of the area ahead of the wearer, processes it to extract relevant information, and uses the results to pass on appropriate signals via the belt.
    Dr. Rus knew from previous attempts to build devices of this sort that what might seem the obvious way of manifesting those signals, namely as sounds with specific meanings, was not a good approach. Blind people depend a lot on their hearing and do not like it when stylish devices hamper this sense with beeps and clicks. Hence the belt, which has five vibrating motors installed in it.
    That configuration permits the computer to warn a wearer when he is on a collision course with an obstacle. It does so by telling the motor pointing most closely in the direction of the obstacle to vibrate. If the wearer is walking towards a wall, for example, the central motor vibrates softly when he comes within a couple of metres of it. If he ignores this, perhaps because he actually wants to reach the wall, the computer increases the amplitude as he closes in, giving him a good idea of exactly how far away he is. When compared with white cane, it reduced blind persons’ collisions with others by 86%.
    The new system can do more than just help someone walk around without collisions, for the belt incorporates a touchpad that is inscribed with instructions in Braille. This permits the user to program it to perform specific tasks.
    For example, Dr. Rus knew that blind students often struggle to find an empty seat in a crowded lecture theatre. Adding an appropriate algorithm to the computer’s software helps get around this by enabling it to recognize chairs, and also whether or not a chair is occupied.
    Whether a camera and a belt could replace a cane completely remains to be seen. In particular, Dr. Rus’s system does lack one important feature of Biggs’s innovation. A white cane not only helps a blind person to navigate, it also signals his condition to the rest of the world, allowing others to adjust their behavior accordingly.
What has Dr. Rus learned from previous attempts?

选项 A、Blind people depend on their devices to a great extent.
B、The sounds can alert wearers when obstacles are encountered.
C、The sound to express signals interferes with the user’s hearing.
D、It’s a good approach to add sounds to devices.

答案C

解析 细节题。由题干中的previous attempts定位到第三段。第三段第一、二句指出,“鲁斯博士根据之前这类设备的开发尝试,得出了一点经验:那种似乎显而易见的显示这类信号的方式——即表达特定含义的声音,实际上并不是一个好办法。盲人非常依赖他们的听觉,不喜欢新奇设备发出的哔哔和嘀嘀声,因为它们干扰了这一知觉。”由此可知,表达信号的声音容易干扰用户的听觉,故正确答案为C项。第三段第二句指出,盲人非常依赖他们的听觉,而不是很大程度上依赖设备,这是细节上的概念偷换,故排除A项。第四段第一句指出,“这样的设置使得计算机在用户快要撞到障碍物时发出警告”,这并不是鲁斯从之前的尝试中得到的经验,故排除B项。文中说在设备中加入声音并不是个好办法,故排除D项。
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