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
2024-05-05
40
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. 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. [31]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.
29. What is the relationship between the vibration of an object and the frequency of its sound?
30. What sounds can humans hear?
31. According to the speaker, what is the phenomenon of echolocation?
选项
A、A bat caught the insect in midair and ate it.
B、Dolphin’s clicking sounds bounced off the fish and back to it.
C、A person heard an echo when he shouted into the valley.
D、A dog heard his owner’s whistle because he used ultrasound.
答案
B
解析
细节题。文中提到,用声音来找或看东西被称为“回声定位法”。之后,短文以海豚为例说明“回声定位法”:海豚会发出尖利的声音,这种声音会撞击到它周围的任何物体,然后通过声波形式再传回到海豚处。通过这种方法,海豚可以找到离自己10英尺以内的小鱼。蝙蝠只是利用回声定位原理“找到”食物,但并非caught或ate,所以可排除强干扰项A。
转载请注明原文地址:https://tihaiku.com/zcyy/3584867.html
相关试题推荐
[originaltext]Whyaresofewtigersman-eaters?Whyarefewerthanthreepe
[originaltext]Thecameraisoftenthoughttobeamoderninvention.Butas
[originaltext]Thecameraisoftenthoughttobeamoderninvention.Butas
[originaltext]Goodmorningeveryone.MynameisCraigStone,andI’llbeyou
[originaltext]Goodmorningeveryone.MynameisCraigStone,andI’llbeyou
[originaltext]Goodmorningeveryone.MynameisCraigStone,andI’llbeyou
[originaltext]Agoodmarriagemeansgrowingasacouplebutalsogrowingas
[originaltext]Agoodmarriagemeansgrowingasacouplebutalsogrowingas
[originaltext]WelcometoEvergladeNationalPark.TheEvergladeisawatery
[originaltext]WelcometoEvergladeNationalPark.TheEvergladeisawatery
随机试题
"GeneralScienceClass"[img]2012q1/ct_etoefm_etoeflistz_1275_20121[/img][br]W
Twoyearsago,myparentsstartedcollectingtheirSocialSecuritychecks,
MyfatherusedtomakemerepeatinghisinstructionstomakesurethatIknewwh
紧耦合多机系统一般通过(请作答此空)实现多机间的通信。对称多处理器结构(SMP)
高应变动力试桩法检测时,当出现下列哪些情况时,应按照工程地质和施工艺条件,采用实
《义务教育化学课程标准(2011年版)》就“探究金属的物理性质和化学性质”的评价
Thechangeinthatvillagewasmiraculou
下边四个图形中,只有一个是由上边的四个图形拼合(只能通过上、下、左、右平移)而成
A.左氧氟沙星片 B.阿奇霉素片 C.注射用阿莫西林 D.注射用头孢曲松钠
广播电视中心通常采用10kV供电,10kV用电设备处的电压偏差允许值为()
最新回复
(
0
)