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
Welcome back, everybody.
I hope you had a great break.
It was 60 years ago that French explorer Jacques Cousteau first identified the
dolphins ability to use echolocation.
Today we're discovering just how amazing this ability really is.
Through echolocation, a dolphin can determine the size, shape, direction, speed,
distance and composition of an object as small as a pingpong ball 100 meters
away.
Simply amazing.
OK. Let's get back to the reading for more amazing dolphin statistics on line
13.
(Music).
Seeing With Echoes.
Researcher Laura Kloepper studies a false killer whale named Kina.
False killer whales are members of the dolphin family.
Kloepper says Kina could distinguish cylinders that were only 0.2 millimeters
apart in size.
In other tests, Kina recognized the difference between objects whose widths
differed by less than the width of a human hair.
Dolphins and whales can alter the width of the stream of sound they use for
echolocation.
They make it wide to gather general information and narrow for detailed
observations.
They also control the sensitivity of their hearing.
When they aren't hunting, they decrease their sensitivity to protect their ears
from loud noises.
As scientists continue to study marine mammals, they are gaining an even deeper
understanding of these creatures' amazing capabilities.
Dolphins are amazing creatures.
They are able to use their sounds that they make in order to see underwater and
understand where things are around them.
Most of the time, though, people use to think that, well, they just had a vague,
or a small, understanding of what was around them.
But right before the break we discovered that echolocation is actually quite a
bit more precise, or accurate, than people usually thought.
Well, how precise is it, and how did we find out?
Well, researcher Laura Kloepper studied a false killer whale, and her name was
Kina.
Now a false killer whale is not actually a killer whale, is it?
That's right.
That's the word "false" there; we know that means something that isn't true.
And so this is actually a dolphin.
It looks like a killer whale.
And you can see a picture of it again on page 16.
That's right.
Now friends, the animal is real.
But these false killer whales are members of the dolphin family instead of being
members of the whale family.
Though if you saw them in nature, you might be a little bit confused.
But since dolphins are the main marine mammal we're talking about that uses
sonar, or uses echolocation, let's see what this researcher discovered.
OK. Well, they were researching a false killer whale named Kina.
And they discovered that this whale could distinguish cylinders that were only
0.2 millimeters apart in size.
OK. Let's find out what a cylinder is.
Now a "cylinder" is a long tubed shape item.
Now it has two circular entrances, one at the top and one at the bottom, and it
is the same size all the way up.
So maybe a pipe would be an example of a cylinder.
Yeah, a pipe or a tube, something like that is a cylinder shape.
They're usually straight, not like a hose.
That's right.
Now the cylinders you can imagine that being only 0.2 millimeters apart in size,
they look to our eyes to be very much the same.
OK. And so in order to see these tiny, little cylinders, it requires a lot of
precision for these whales.
Well, the cylinders weren't necessarily that small, it's just the differences in
them where that small.
And that is how precise their sonar echolocation is.
OK, so.
Now we see in other tests here, Kina was able to recognize the difference
between objects whose widths differed by less than the width of a human hair.
Oh, my goodness, Ryan.
That's incredible.
I mean, look at your hair, friends.
Take a look at just one strand of hair.
Do you see how thin that is?
Now using echolocation, dolphins can tell the difference in size by less than
half of your hair!
Now I don't know about you, friends, or you, Kaylah,
but I don't even think I could see the difference between two different objects
that were only different by the width of a human hair.
I don't think we would, definitely to the human eye.
And maybe even to a dolphin's eye they can't tell the difference.
But to their sound, they can.
OK. So they can alter the width of the stream of the sound that they use for
echolocation.
Now we can see here that we're adding whales to the list of mammals that are
using this.
If you've ever heard a whale call,
you can imagine that the high-pitched singing that a whale does serves the same
purpose as the clicking noise you made earlier, Ryan.
Yeah, exactly.
Those sounds bounce off of walls and they can hear what is around them.
And now we know they alter, or change, the width of the sound, or the pitch -
how high it is, how low it is or how many clicks they're making.
OK. So "width" meaning how... how far, how much... where the pitch is as you
said, kind of how low or how high pitched it is.
And each one of those sounds can send back a different kind of echo.
OK. Now Kaylah, why would they do that?
Well, they make it wider to gather general information, and then narrow for
detailed observations.
So a very wide sound lets them see a broad area.
And then they use a narrow one to get the specifics of something.
Yeah, narrow, or small.
And that way they can see the detailed, or small, observations.
Now they also control the sensitivity of their hearing.
Now "sensitivity" is determining how well they can hear something.
Right. Sensitivity is your reaction to something.
Now when they aren't hunting, they decrease their sensitivity, or what they can
sense, to protect their ears from loud noises.
That's right.
So the sensitivity is their ability to take in that information and process it
to find things out.
So they... they can change that so that they don't hurt their ears.
OK. As scientists continue to study marine mammals,
they are gaining an even deeper understanding of these creatures' amazing
"capabilities," which means what they're able to do.
That's right.
They have amazing capabilities.
Their ability to do something is absolutely incredible using this echolocation.
OK. Now friends, let's go visit the Chat Room.
How to take better care of your hair.
Ken, is something wrong with your hair?
No, not my hair.
My wife wanted me to look up ways to prevent split hairs.
Split hairs?
That's right.
She dyes her hair sometimes.
And lately she's been discovering that some of her hairs are split at the end.
Oh. You're talking about split ends, not split hairs.
Split ends?
That's right.
Split ends happen when the end of your hair split into two or more strands.
It's often caused by hair dye or high heat from a hair dryer.
So I can't say split hairs?
No. "Splitting hairs" has a very different meaning.
If you split hairs, you're arguing about very small differences or unimportant
details.
Oh. What does hair have to do with unimportant details?
Have you ever tried splitting a hair, Ken?
Splitting a hair?
Sure! I just take some scissors and cut it in half.
No, Ken. I mean to split it lengthwise.
Lengthwise?
I would probably need to use laser surgery equipment to do that.
Exactly.
So the point is that taking a hair and splitting it lengthwise never makes
sense.
It is a completely pointless activity that takes a great deal of time and effort
and produces a result of little worth.
Thus to describe something as being like splitting hairs means that it is also
pointless.
I see. Well, not to split hairs, but I think I've learned all I want about
splitting hairs.
That's right.
Well, on to the split ends.
Thanks, Bryan.
(Chinese).
Hi, everyone. I'm Michelle.
(Chinese).
And that concludes our Language Tips today.
I'll see you next time.
Bye-bye.
Thank you, Michelle.
We certainly appreciate that.
Dolphins use a very precise form of echolocation to observe their surroundings.
This is similar to the sonar that bats and even some humans use to get around.
Do you remember a few years ago Studio Classroom did a PROFILE on a young blind
man who used echolocation to play basketball, ride a bicycle and skateboard?
Friends, how can you not be amazed by the facts found in today's lesson?
Use this lesson's Talk About It questions to talk about it.
And then join us tomorrow for a new lesson.
Until then, have a great day.