A blind baby is doubly handicapped. Not only is it unable to see, but because it cannot receive the visual stimulus（刺激）from its environment that a sighted child does, it is likely to be slow in intellectual development. Now the ten-month old son of Dr. and Mrs. Dennis Daughters is the subject of an unusual psychological experiment designed to prevent a lag（滞后）in the learning process. With the aid of a sonar-type electronic that he wears on his head, infant(婴儿) Dennis is learning to identify the people and objects in the world around him by means of echoes(回声). The device is an improvement of the “Sonicguide”, an instrument produced by Telesensory Systems, Inc., of Palo Alto, Calif, and used by blind adults in addition to a smart or guide dog. As adapted for Dennis, it consists of a battery-powered system about the size of a half dollar that is on a headgear. A transmitter sends out an ultrasonic(超声的) pulse that creates an 80 degree cone of sound at 6 feet. Echoes from objects within the cone are perceived (felt) as sounds that vary in pitch(音调) and volume(音量) with the size and distance of the object. The closer an object is, the lower the pitch, and the larger the object, the louder the signal. Hard surfaces produce a sharp ping, while soft ones send back signals with a slightly fuzzy quality. An object slightly to the right of Denny’s sends back a louder sound to his right ear than to the left. Thus , by simply moving his head right and left and up and down, he can not only locate an object but also get some notion of its shape and size, thanks to the varying qualities of sounds reaching his ears as the cone of ultrasound(超声波) passes its edges. Dennis likes to use the device to play a kind of peek-a-boo with his mother. Standing on her knee and facing her directly, he receives a strong signal in both ears. By turning his head away, he makes her seem to disappear. “From the first time he wore it,” says Mrs. Daughters, “it was like a light going on in his head.” What remains to be determined is how well the device will help Dennis cope with his surroundings as he begins to walk and venture further into his environment. Meanwhile, Telesensory, Inc, is working on the development of sonar(声纳) device with somewhat the same sensitivity as Dennis’s for use by school-age children. 小题1:Dr. and Mrs. Daughters’ research is directed to ________.
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