首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
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 hear
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 hear
admin
2021-07-14
31
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. 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.
9. What is the relationship between the vibration of an object and the frequency of its sound?
10. What sounds can humans hear?
11. 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。录音提到,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://kaotiyun.com/show/7gJ7777K
0
大学英语六级
相关试题推荐
当下人们倡导更健康的生活方式,自行车已再度回归人们的生活,重新成为人们重要的出行工具。
A、ItisthebiggestAmericanonlinegrocer.B、Itcanmakeaprofitfromitsonlineoperation.C、ItscustomersaremainlyfromMa
Thereisneveragoodtimetohaveaheartattack,butthewisepersonafflictedwithcloggingarteries(动脉堵塞)mightwanttobees
Thereisneveragoodtimetohaveaheartattack,butthewisepersonafflictedwithcloggingarteries(动脉堵塞)mightwanttobees
A、Hisformerheadmaster.B、Hisformerclassmate.C、Hisformerclosestfriend.D、Hisformerlunchlady.D①选项都是指人的名词,预测问题与人物相关。②问题
Childrenwholivenearamainroadareingreaterdangerofcatchingpneumonia(肺炎)becausepollutionfrompassingtrafficdamages
A、JapanesestudentsstudymuchharderthanColumbianstudents.B、ColumbianstudentsscorehigherthanJapanesestudentsinmaths
Smallcommunities,withtheirdistinctivecharacter—wherelifeisstableandintenselyhuman—aredisappearing.Somehave【C1】____
Inwhat’sprobablythecraziestheadlineI’veeverwritten,I’vereportedthat【C1】______inlivestockprotectionarehappening
A、Thosewithfrequencieslowerthan20hertz.B、Thosewithfrequenciesabout21,000hertz.C、Thosewithfrequencieslowerthan2
随机试题
Weareatyourservice.Don’t______toturntousifyouhaveanyproblems.
鲁迅著名的杂文集有
血虚发热证的首选方为阳虚发热证的首选方为
某新建的大型建设项目,建设前后噪声级增高量为2dB(A),受噪声影响人口增加不多,此建设项目声环境影响应按()进行工作。
接入网的传送功能就:是为接入网不同地点之间公用承载通路的传送提供通道,同时也为所用传输媒质提供媒质适配功能。具体功能有()。
根据物业管理企业业务活动的特点以及各责任实体的权限,责任中心一般分为()。
社会工作者在一次走访中发现王老先生独自在家。对于社会工作者的到来,他很高兴。交谈中社会工作者了解到,王老先生现与儿子一家同住,儿子和儿媳外出工作时,家里只留下他一个人。社会工作者观察发现,王老先生的房间杂乱无章,身上衣服泛黄并发出异味,已经多日没有换洗。老
足球技术包括哪些内容?
简要论述新闻与宣传的区别。(中国传媒大学,2014年)
WhatdoesanadvertisementsayaboutEnglishlearning?
最新回复
(
0
)