首页
登录
职称英语
[originaltext]Objects that are vibrating make sounds. Rhythmic sound vibrations
[originaltext]Objects that are vibrating make sounds. Rhythmic sound vibrations
游客
2024-03-29
8
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. [23] 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. [24] 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. [25-1] Using sound to find or “see” things is called echolocation. Another animal that uses ultrasound is the dolphin. Dolphin scan hear sounds up to about 150,000 hertz. Dolphins use sound waves to find food underwater. [25-2] 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. [25-3] Dolphins’ ultrasound ability is so sensitive that they can detect small fish from 10 feet away.
23.What is the relationship between the vibration of an object and the frequency of its sound?
24.What sounds can humans hear?
25.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
转载请注明原文地址:https://www.tihaiku.com/zcyy/3531150.html
相关试题推荐
[originaltext]Objectsthatarevibratingmakesounds.Rhythmicsoundvibrations
[originaltext]Objectsthatarevibratingmakesounds.Rhythmicsoundvibrations
[originaltext]Inorderforachemicaltobeconsideredadrug,itmusthavethe
[originaltext]Inorderforachemicaltobeconsideredadrug,itmusthavethe
[originaltext]Hi,everybody.AsIsaidinmyStateoftheUnionaddress,weliv
[originaltext]IntheUnitedStates,manypeopleoncelivedinlarge,two-and-th
[originaltext]Easterisamixofthreetraditions:Pagan,HebrewandChristian.
[originaltext]Easterisamixofthreetraditions:Pagan,HebrewandChristian.
[originaltext]Easterisamixofthreetraditions:Pagan,HebrewandChristian.
[originaltext]W:2millionhighschoolseniorsaregearingupthisfalltoappl
随机试题
[originaltext]W:Ijustmadeupaquartoforangejuicethismorning,andnowI
横缝的间距一般为()。A.10~15m B.15~20m C.20~30m
遵守医学伦理道德,尊重患者的知情(),为患者保守医疗秘密和健康隐私,维护患
患者,男,35岁。3周前突患肩臂疼痛,伴有麻木不仁,活动受限,受凉则痛势加剧,近
右边表格中的内容反映的是()。 A.管仲改革 B.商鞅变法 C.孝文
下列对紫外线灭菌法的叙述,错误的是A.一般用于灭菌的紫外波长是220~290nm
材料一 中国共产党有一个非常优秀的传统,也是中国共产党的巨大优势,就是始终坚持
某个人独资企业投资人在申请企业设立登记时明确以其家庭共有财产作为个人出资。为维持
张某租用一门面开办的美容店,税务部门以张某逃税为由查封美容店,并扣押美容仪器设备
有一45岁妇女,近几日出现情绪低落、郁郁寡欢、愁眉苦脸,不愿和周围人接触交往,悲
最新回复
(
0
)