节目资讯
刊物:空中英语教室
日期:2012-10-04
难易度:High
关键字:penetrate, marine, sensitivity, capability, echolocation, cylinder
Hi, everybody.
Welcome to Studio Classroom Worldwide.
Thanks for joining us today.
My name is Steve.
You know, living in the 21st century, we think we know a lot.
And if we don't know it, we can Google it in a second.
Well, this month's SCIENCE lesson reminds us that as advanced as we are, there
are still plenty of things in this world we don't know or understand.
Take dolphins, for example.
We knew for a while that they use sounds to communicate and navigate.
But we didn't know just how precise, how powerful and how complex this ability
really is.
So let's learn more about how dolphins use sound to see on page 16.
(Music).
Seeing With Echoes.
Dolphins and other underwater animals sense their surroundings through sound.
Dolphins travel regularly between the water's surface and the depths of the
ocean.
They have keen vision both in and out of the water.
But when they dive deeper than light can penetrate, they must rely on a
different sense - hearing.
Several species of marine mammals observe the world through echolocation.
They send out a stream of clicks that bounce off the objects around them.
By listening to the echoes of these sounds, dolphins can determine the size,
shape and location of nearby objects.
Recent scientific research has shown that this echolocation is more precise than
anyone had previously imagined.
Hello, friends.
Thank you for joining us.
My name is Ryan.
And my name is Kaylah.
And today we are in our SCIENCE article in our Studio Classroom magazines.
Now usually SCIENCE articles are about technology, but this SCIENCE is connected
to nature.
That's right.
We're looking at the science of how some animals are able to see with echoes.
Now first, friends, you should know what an echo is.
An echo is the sound that you hear that reflects or bounces off of something.
Can you help explain that, Kaylah?
OK. If you were in an empty hallway and you made a loud noise, the sound that
comes back is called your echo.
So these animals actually see by listening for the echoes.
Now specifically, we're talking about dolphins and other underwater animals that
sense their surroundings through sound.
OK. Now you can see a picture of a dolphin there on page 16.
And this animal is able to sense, or see, or understand their surroundings, what
is around them through sound.
OK. Well, we're going to see how they do that.
Now dolphins travel regularly between the water's surface and the depths of the
ocean.
Now friends, they would do that because dolphins breathe oxygen.
They're not like fish.
They need air, so they would have to go to the surface to get oxygen.
Yeah. The surface is the top of the water, and they will then dive down to the
depths of the ocean.
The word "depths" is referring to the deepest parts.
That's right.
They go very, very deep.
Now you might think it would be hard for them to swim on both the top and the
bottom of the water, but they have keen vision both in and out of the water.
OK. Now this is an interesting fact considering that dolphins live in the water.
But even when they are out of the water, they still have keen vision.
Now "keen" means very good or very strong, or very easy to use.
They've got great vision both underwater and above water.
Yeah. We usually... use the word "keen" to describe your senses: how well you
can see, how well you can hear or maybe how well you can think.
Now earlier we said that they dive to depths.
Well, we need to see just how deep are they diving.
Well, sometimes they dive deeper than light can penetrate.
And then they must rely not on sight but on a different sense - and that is
their hearing.
OK. Now friends, let's talk about the word "penetrate." If something penetrates,
that means it moves through something.
Or that can also mean that it moves into something.
And so here, the light can not move through the water deep enough, or as deep as
the dolphins can swim.
That's right.
Friends, you know if you go very deep underwater, it's dark.
Now dolphins dive that deep, and you can't see without light no matter how good
your vision is, so they rely on their hearing to move around.
OK. Now several species of marine mammals observe the world through
echolocation.
OK, let's go through this.
"Marine" mammals, first of all, is a word we need to look at.
We know mammals are animals that breathe air and give birth to their babies.
Now "marine" refers to the water.
So it has to do with water.
That can be boats or animals or plants that all belong in a water situation.
OK. So these are sea creatures.
And they... many of them use echolocation.
Friends, "echolocation" is also something that might be called sonar.
And that is a set of sounds or clicks that are made and then the echos bounce
back.
So you might have heard a dolphin before, it goes... makes that sound.
And they can hear that underwater.
Now they send out a stream or a whole set of clicks that bounce off the objects
around them, and then through their listening, can determine things.
Now that is our Grammar on the Go sentence, so we're going to talk more about
it.
But first, let's visit Liz.
Hi, friends.
I hope you're doing well today.
My name is Liz.
And it's time for Grammar on the Go.
I'm at an ocean park here in Hualien.
And this is a great place to see and learn about underwater animals.
Speaking of underwater animals, our SCIENCE article this month is about how
underwater animals can travel around without seeing.
And here's our Grammar Tip sentence.
They send out a stream of clicks that bounce off the objects around them.
Our Grammar Tip focus today is on the word: stream.
We normally use "stream" to talk about a very small river.
But in today's sentence, "stream" has a different meaning.
Here it means a large number of something, and these things happen one after
another.
In the case of today's sentence, the writer is talking about a large number of
clicks, and these clicks are made one after another.
So they are a stream of clicks.
We can use "stream" to describe phone calls.
If you have a lot of phone calls coming in and you find yourself answering the
phone again and again, then you have a stream of phone calls.
Or, if a company developed a product that wasn't very good, then customers will
be sending a stream of complaints.
Or let's say you've been away on vacation and now you're finally back at work,
chances are you would have a stream of e-mails to answer.
And that's all the time we have for today.
Thanks again for joining me here.
I hope to see you all again real soon.
Until then, this is Liz with Grammar on the Go, signing off, in Hualien.
Bye-bye.
Thank you, Liz.
Well, dolphins use series of clicks to find out where they're going underwater.
By listening to the echoes of those sounds, dolphins can determine, or
understand, the size, shape and location of nearby objects.
And it is very important that they can determine the location and the shape and
the size of objects so they don't run into them even if it is dark.
OK. Well, there has been recent scientific research on dolphins.
And it's shown that this type of echolocation is actually more precise, or more
accurate, than anyone had previously imagined.
That's right. It's more precise.
And we're going to learn just how precise and accurate their echolocation is
after we watch today's skit.
Hello, little dolphin.
I know all about you.
You do?
Oh, yeah.
Yeah. You're friendly and smart and you see very well.
That is true about dolphins.
Yeah. You like to dive between the surface of the water way down to the depths
of the sea.
Oh. You know a lot.
Oh, yeah.
Dolphins have keen vision.
But when you dive deep down where the light doesn't penetrate, you use your
sense of hearing.
Ooh.
Yeah. That's called echolocation.
You send out a stream of clicks... the sound bounces off objects.
Whoa! Then waht happens?
Well, by listening to the echoes, you can determine the size, shape and location
of nearby objects.
Oh. That's very clever, isn't it?
Yes, it's very clever and precise.
Echolocation, it's a very useful skill.
It sure is.
But unfortunately, I can't do that.
Sure you can.
All dolphins can.
Yeah. But I'm not a dolphin.
You're not?
No. I'm a shark.
A shark?