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托福TPO-07 Lecture2

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Pro:So, that is how elephant uses infrasound.

教授:好了,大象就是这样运用次声波的。
Now, let's talk about the other and the acoustic spectrums, sound that is too high for humans to hear-ultrasounds.
现在我们来讲讲另一种声谱,一种极高的以致于人类听不见的声音—超声波。
Ultrasound is used by many animals that detected and some of them seen out very high frequency sounds.
超声波是许多动物用来侦查或识别的一种高频声音。
So, what is a good example? Yes, Kayo.
那么,能举出什么好的例子吗?嗯,卡阳。
Kayo:Well, bats, since there is all blind, bats have to use sound for,
卡阳:我想到了蝙蝠。因为蝙蝠都没有视觉,所以它们不得不用声音来辨别方向,
you know, to keep them from flying in the things.
你知道的,以免飞行的时候撞到东西。
Pro:That is echolocation.
教授:那是回声定位。
Echolocation is pretty self-explanatory; using echoes reflected sound waves to located things.
回声定位其实不言自明,就是用回声反射声波来定位事物。
As Kayo said that bat used for navigation and orientation.
就像卡阳举出的导航和定位,
And what is else. Mike.
你还有什么例子呢?麦克。
Mike:Well, finding food is always important, and I guess not becoming food for other animals.
麦克:呃,觅食是很重要的,我猜是不想成为其他动物的猎物。
Pro:Right, on both accounts.
教授:是的。两个方面都对。
Avoiding other predators, and locating prey, typically insects that fly around it at night.
躲避捕猎者,定位猎物,昆虫基本都在夜间飞行。
Before I go on, let me just respond something Kayo was saying-this idea that is bats are blind.
在我继续往下讲之前,我先回复一下刚刚卡阳说的问题,就是说蝙蝠都是没有视觉的。
Actually, there are some species of bats, the one that don't use echolocation that do rely on their vision for navigation,
其实,蝙蝠的一些物种是不依赖回声定位,而是用视觉进行导航的。
but its true for many bats, their vision is too weak to count on.
但是确实,很多蝙蝠的视力太差了,基本起不到什么作用。
Ok, so quick some rays if echolocation works.
好了,我们很快来讲一下回声定位适用的情况。
The bats emit the ultrasonic pulses, very high pitch sound waves that we cannot hear.
蝙蝠发出超声波脉冲,很高分贝的声波以致于我们人类听不到。
And then, they analyze the echoes, how the waves bound back.
然后,它们分析回声,声波是如何反射回来的。
Here, let me finish the style diagram I started it before the class.
在这里,让我先把课前提到的图表讲完。
So the bat sends out the pulses, very focus birds of sound, and echo bounds back.
那么蝙蝠发出脉冲,就是很集中的鸟声,然后回声反射。
You know, I don't think I need to draw the echoes, your reading assignment for the next class;
我想我不用画声波图了,这将是我下节课给你们布置的阅读作业,
it has diagram shows this very clearly.
其中会有图表给你们很清晰的展示。
So,anyway, as I were saying, by analyzing this echo, the bat can determine,
无论如何,正如我刚才说的,通过分析回声,蝙蝠就能知道,
say, if there is wall in a cave that needs to avoid, and how far away it is.
比如说,如果洞中有墙需要躲避,以及墙的距离有多远。
Another thing uses the ultrasound to detect is the size and the shape of objects.
超声波还有一个用途就是探测物体的大小和形状。
For example, one echo they quickly identified is one way associated with moff, which is common prey for a bat, particularly a moff meeting its wings.
比如,它们迅速鉴别的一种回声方式和飞蛾有关,飞蛾是蝙蝠的一种食物,尤其是那种飞行时翅膀相交的飞蛾。
However, moff happened to have major advantage over most other insects.
然而,飞蛾碰巧也比其他昆虫占有优势。
They can detect ultrasound; this means that when the bat approaches, the moff can detect the bat's presence.
它们能够探察到超声波,这就意味着当蝙蝠靠近的时候,它们会知道蝙蝠的存在。
So, it has time to escape to safety, or else they can just remain motionless. Since, when they stop meeting their wings, they will be much hard for the bat to distinguish from, oh… a leave or some other object.
因为,它们有时间逃到安全地带,或者它们也可以纹丝不动。因为一旦它们不再煽动翅膀,蝙蝠就很难将它们从树叶或者其它物体辨别开来。
Now, we have tended to underestimate just how sophisticated the ability that animals that use ultrasound are.
那么现在我们就知道动物在运用超声波的时候的非凡经验了。
In fact, we kinds of assume that they were filtering a lot out.
事实上,我们推断蝙蝠在分析回声时过滤掉了很多因素。
The ways are sophisticated radar on our system can ignore the echo from the stationary object on the ground.
我们系统里精密的雷达能够忽略地面上静止物体的回声。
Radar are does this to remove ground clutter, information about the hills or buildings that they doesn't need.
雷达借此可以剔除地面杂乱回波及关于山丘、建筑物等不必要的信息。
But bats, we thought they were filtering out kinds of information, because they simply couldn't analyze it.
而蝙蝠,我们起初认为它们过滤掉了很多因素,仅仅是因为它们不能够分析到这些因素。
But, it looks as we are wrong.
然而我们错了。
Recent there was the experiment with trees and specific species of bat.
最近有一次关于树木和特种蝙蝠的实验。
A bat called:the laser spear nosed bat.
这种蝙蝠叫做激光枪鼻蝙蝠。
Now, a tree should be huge and acoustic challenge for bat, right?
那么,树木对于蝙蝠来讲应该是很大,且声学挑战极高对吧?
I mean it got all kinds of surfaces with different shapes and angles.
我的意思是,树木的表面形状角度各不相同。
So, well, the echoes from trees are going to be massive and chaotic acoustic reflection, right, not like the echo from the moff.
因此,从树木上反射的回声将会是大量且嘈杂的,是的,不像从飞蛾上反射回来那样简单。
So, we thought for a long time that the bat stop their evaluation as simply that is tree.
我们一直以为蝙蝠对树的概念仅仅是树木而已。
Yet, it turns out that is or at least particular species, cannot only tell that is trees, but can also distinguish between a pine tree, deciduous tree, like a maple or oak tree, just by their leaves.
而结果却是有些种类的蝙蝠不仅能感知到树木,还能仅通过树叶就会区分开松树、落叶树,比如说枫树或者橡树。
And when I say, leaves, I mean pine needles too. Any idea on how we would know that?
我所谓的树叶,还包括松针。知道我们怎么获悉的吗?
Students:Well, like with the moff, could be their shape?
学生:呃,比如飞蛾,就是树叶的形状?
Pro:You are on the right track-it actually the echo of all the leaves as whole the matters.
教授:思路很对-实际上是所有树叶组成整体的一个回声。
Now, think, a pine trees with little densely packed needles.
现在大家想象一棵松针并不茂密的松树,
Those produced a large number of fain reflection in which what's we called as:a smooth of echo.
那么就会产生许多简单的反射,我们称作平滑回声,
The wave forms were very even,
这种声波非常的平均。
but an oak which has fewer but bigger leaves with stronger reflections, produces a gigots wave form, or what we called:a rough echo.
但是橡树这种树叶少且树叶大的树木就会有更强的回声,会产生一种复杂的声波,或者我们称之为粗糙回声。
And these bats can distinguish between a two, and not just was trees, but with any echo come in smooth and rough shape.
而蝙蝠能够区别树木并不仅因为树木本身,而还是通过判断回声是平滑的还是粗糙的。

重点单词   查看全部解释    
respond [ris'pɔnd]

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v. 回答,答复,反应,反响,响应
n.

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specific [spi'sifik]

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adj. 特殊的,明确的,具有特效的
n. 特

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smooth [smu:ð]

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adj. 平稳的,流畅的,安祥的,圆滑的,搅拌均匀的,可

 
stationary ['steiʃənəri]

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adj. 不动的(稳定的)
n. 固定物(驻军

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prey [prei]

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n. 被掠食者,牺牲者
vi. 捕食,掠夺,使

 
ignore [ig'nɔ:]

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vt. 不顾,不理,忽视

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massive ['mæsiv]

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adj. 巨大的,大规模的,大量的,大范围的

 
pitch [pitʃ]

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n. 沥青,树脂,松脂
n. 程度,投掷,球场

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emit [i'mit]

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vt. 发出,放射,吐露

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reflection [ri'flekʃən]

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n. 反映,映像,折射,沉思,影响

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