首页
登录
职称英语
[originaltext] Objects that are vibrating make sounds. Rhythmic sound vibra
[originaltext] Objects that are vibrating make sounds. Rhythmic sound vibra
游客
2024-05-30
11
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. [29] The more rapid, 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. [30] 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 ultra sound. 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. [31]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 l0 feet away.
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
转载请注明原文地址:https://tihaiku.com/zcyy/3611869.html
相关试题推荐
[originaltext][32]Inthepastindustrieshadmorefreedomthantheyhaven
[originaltext][32]Inthepastindustrieshadmorefreedomthantheyhaven
[originaltext][32]Inthepastindustrieshadmorefreedomthantheyhaven
[originaltext][31]Theeconomiccostsofnoisetosocietyareseveral.[29
[originaltext]W:Hello,Michael.Wouldyoucometomyofficeforaminute?Iwa
[originaltext]W:Hello,Michael.Wouldyoucometomyofficeforaminute?Iwa
[originaltext]M:Areyougoingtothedemonstrationtohelpstopthespreadof
[originaltext]W:Doyouwantmetoexplainthesequestionsbeforetheexam?M:
[originaltext]W:Doyouwantmetoexplainthesequestionsbeforetheexam?M:
[originaltext]W:Doyouwantmetoexplainthesequestionsbeforetheexam?M:
随机试题
Writeanargumentationbasedonthefollowingtopicandelaborateyourpointof
Spaceisadangerousplace,notonlybecauseofmeteors(流星)butalsobecause
[originaltext]Authoritiessayeveryonehasbeentransferredfromaluxuryh
关于建筑物内的吊顶处理,下列哪一项是不妥的?()A.应设检修口及通风口 B
不属于脂质体质量要求的是()。A:融变时限 B:形态、粒径及其分布 C:包
(9分)乙餐厅定期采购大米,已知该餐厅每天需要大米300千克,大米的价格为3.2
下列说法正确的是()。A.企业的员工招聘工作不仅是企业的一项经济活动,而且具有
私人物品与公共物品的主要区别在于()。A.前者是私人提供的,后者是政府提供的
在乙有限责任公司设立过程中,出资人甲以乙公司名义与他人签订一份房屋租赁合同,所租
建设工程设计阶段进度控制的主要任务是()。A.工期控制 B.质量控制 C.出
最新回复
(
0
)