Bats蝙蝠
In what way does echo-location in bats play an utilitarian role?
Not all sounds made by animals serve as language, and we have only to turn to that extraordinary discovery of echo-location in bats to see a case in which the voice plays a strictly utilitarian role.
To get a full appreciation of what this means we must turn first to some recent human inventions. Everyone knows that if he shouts in the vicinity of a wall or a mountainside, an echo will come back. The further off this solid obstruction, the longer time will elapse for the return of the echo. A sound made by tapping on the hull of a ship will be reflected from the sea bottom, and by measuring the time interval between the taps and the receipt of the echoes, the depth of the sea at that point can be calculated. So was born the echo-sounding apparatus, now in general use in ships. Every solid object will reflect a sound, varying according to the size and nature of the object. A shoal of fish will do this. So it is a comparatively simple step from locating the sea bottom to locating a shoal of fish. With experience, and with improved apparatus, it is now possible not only to locate a shoal but to tell if it is herring, cod, or other well-known fish, by the pattern of its echo.
It has been found that certain bats emit squeaks and by receiving the echoes, they can locate and steer clear of obstacles -- or locate flying insects on which they feed. This echo-location in bats is often compared with radar, the principle of which is similar.
参考译文
动物发出的声音不都是用作语言交际。我们只要看一看蝙蝠回声定位这一极不寻常的发现,就可以探究一下声音在什么情况下有绝对的实用价值。
要透彻理解这句话的意义,我们应先回顾一下人类最近的几项发明。大家都知道,在墙壁或山腰附近发出的喊声,就会听到回声。固体障碍物越远。回声返回所用时间就越长。敲打船体所发了的声音会从海底传回来,测出回声间隔的时间,便可算出该处海洋的深度。这样就产生了目前各种船舶上普遍应用的回声探测仪。任何固体者反射声音,反射的声音因物体的大小和性质的不同而不同。鱼群也反射声音。从测定海深到测定鱼群,这一进展比较容易。根据经验和改进了的仪器,不仅能够确定鱼群的位置,而且可以根据鱼群回声的特点分辨出是鲱鱼、鳕鱼,这是人们所熟悉的其他鱼。
人们发现,某些蝙蝠能发出尖叫声,并能通过回声来确定并躲开障碍物,或找到它们赖以为生的昆虫。蝙蝠这种回声定位常常可与雷达相比较,其原理是相似的。
英国圣诞传统知识问答
国际英语资讯:Spotlight: United Nations bidding farewell to 2017 amid challenges, hopes
国际英语资讯:Firefighters battling Californias wild fire on Christmas Day
国内英语资讯:China to advance energy revolution, enhance global cooperation: vice premier
体坛英语资讯:Leaders China, United States fight hard for 3-2 win, to meet on Monday
英国女王2017圣诞演讲:家是温馨、熟悉和爱的来源
我国多地区陷入天然气供应告急
来纽约第五大道,享用真正的“蒂芙尼早餐”
国际英语资讯:U.S. Senate approves North Macedonia to NATO
国际英语资讯:Russia bans opposition leader from running for presidency in 2018
国内英语资讯:China Focus: CPC unveils regulation to promote transparency in Party affairs
Christmas gift alternatives 不一样的圣诞礼物
国内英语资讯:China Focus: China wins global applause for efforts in world peacekeeping
Therapy, treatment and remedy 三个与“治疗”有关的单词
深圳自动驾驶公共汽车上路试运行
体坛英语资讯:Jiangsu wins 5th straight by beating Beijing
国际英语资讯:Protests continue across Lebanon despite PMs reform measures
国际英语资讯:Family of 9 members killed in Saudi-led airstrikes in Yemens Sanaa
NASA提出新的概念引擎,据说能达到光速的99%
体坛英语资讯:Real Madrid and Athletic Bilbao set pace in La Liga
体坛英语资讯:Iran lift Asian Mens Volleyball Championship title
国际英语资讯:Pompeo, Japanese FM hold phone talks over Iran
Britain's historic landmarks to be protected 英格兰新增一批“受保护历史建筑”
体坛英语资讯:Chinese players impress in Hainan Chess Open
国内英语资讯:Chinese oil giant hands over last set of oil-refining equipment to Kuwaiti contractor
别怪我扫兴,但喝酒真的致癌
国际英语资讯:Pardon of ex-president Fujimori sparks protests, controversy in Peru
体坛英语资讯:Bolivia midfielder Chumacero joins Mexicos Puebla
体坛英语资讯:China sweeps weightlifting worlds with multiple records
为什么一到新年就要下决心?原来这是个悠久传统
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |