首页
登录
职称英语
[originaltext] Objects that are vibrating make sounds. Rhythmic sound vibrat
[originaltext] Objects that are vibrating make sounds. Rhythmic sound vibrat
游客
2023-08-19
70
管理
问题
Objects that are vibrating make sounds. Rhythmic sound vibrations produce sound waves which travel in every direction. The frequency of a sound is the number of waves that pass a given point each second. The more rapidly an object vibrates, the greater the frequency of sound it makes. Frequency is measured in hertz. One hertz equals one sound wave per second. The frequency of sound determines the degree of highness or lowness of the sound. A high-pitched sound has a higher frequency than a low-pitched sound. [20]Humans hear sounds that have frequencies from about 20 hertz to 20,000 hertz. Sound with a frequency higher than 20,000 hertz is called ultrasound which is too high-pitched for humans to hear. However, many animals can hear ultrasound. Bats can hear higher sounds than any other animal. Some can hear up to 210,000 hertz. Bats send out lots of high-pitched squeaks and then listen to the echoes bouncing off things like insects. The shorter the time interval between the squeak and the echo, the closer they are to the insect. Using sound to find or "see" things is called echolocation. Another animal that uses ultrasound is the dolphin. Dolphins can hear sounds up to about 150,000 hertz. Dolphins use sound waves to find food underwater. [21] They make clicking sounds that hit whatever is around them and then bounce back to the dolphins. Dolphins can send as many as 2,000 clicks per second. Dolphins’ ultrasound ability is so sensitive that they can detect small fish from 10 feet away.
19. What is the relationship between the vibration of an object and the frequency of its sound?
20. What sounds can humans hear?
21. According to the speaker, what is the phenomenon of echolocation?
选项
A、Those with frequencies lower than 20 hertz.
B、Those with frequencies about 21,000 hertz.
C、Those with frequencies lower than 20,000 hertz.
D、Those with frequencies higher than 20,000 hertz.
答案
C
解析
细节题。文中提到,人类可以听见频率在20赫兹到2万赫兹之间的声音。由此可知,C为正确答案。
转载请注明原文地址:https://tihaiku.com/zcyy/2939278.html
相关试题推荐
[originaltext]AmericanvisitorstoEasternAsiaareoftensurprisedandpuz
[originaltext]AmericanvisitorstoEasternAsiaareoftensurprisedandpuz
[originaltext]InBritainthebiggestnumberofworkingforeignerscomesfro
[originaltext]Thefamilyischanging.Inthepast,grandparents,parents,a
[originaltext]Thefamilyischanging.Inthepast,grandparents,parents,a
[originaltext]M:I’msotired,Ican’tseestraight.W:You’vebeentiredalot
[originaltext]M:I’msotired,Ican’tseestraight.W:You’vebeentiredalot
[originaltext]M:I’msotired,Ican’tseestraight.W:You’vebeentiredalot
[originaltext]W:Haveyouevervisitedaredwoodforest?Irecentlyhadachanc
[originaltext]W:Haveyouevervisitedaredwoodforest?Irecentlyhadachanc
随机试题
Aroundtheworldmoreandmorepeoplearetakingpartindangeroussportsan
Thereareabout105malesbornforevery100females,butthis【B1】______dro
中发【2004】16号文件全称是什么?文件中关于加强和改进大学生思想政治教育工作
现代高校的基本职能是()。A.发展科学 B.社会服务 C.促进经济发展
可作为蒽酮类化合物的定性鉴别反应的是A.BOrntrager’s反应 B.Ke
血清蛋白电泳时通常用pH8.6缓冲液,此时各种蛋白质带有的电荷为()A.白蛋
平心而论,自古至今闲逸都是一种奢侈品,它取决于两个一般人最难以企及的前提:物质上
A.透明软骨退行性变 B.骨赘形成 C.非特异性滑膜炎 D.关节囊纤维变性
工程质量事故经技术处理后符合《建筑工程施工质量验收统一标准》规定的,经过检查或必
隧道监控量测时,量测部位和测点布置,应根据()等确定。A.地质条件 B.量测
最新回复
(
0
)