Seeing with Echoes

Dolphins and other underwater animals sense their surroundings through sound
海生动物“以耳代目”的关键一回声。海豚与其他水中动物透过声波感应周围环境。

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.

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 sensitively 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.


Grammar Tips:
They send out a stream of clicks that bounce off the objects around them.
"stream " - small river, but here refer to  "a large number of something that one after another.
a stream of phone calls - when you are getting so many phone calls one after another in a period of time.
a stream of complaints.
a stream of emails - many many emails wait for you to answer.


Vocabulary Tips:
penetrate (v)- move through something. 穿透，渗透，刺透。射入。
* Rays of sunlight penetrated the forest.
*The singer's voice can penetrate audiences' hearts.
*One hacker penetrated the bank's computer system.
sensitivity - quick reaction .敏锐，敏感。
*The medicine can cause sensitivity to sunlight.
*As recording technician, you need great sensitivity to good melodies.
sensitive (adj) -敏锐的，敏感的。
capability -能力，才能，能耐。
*Edward has the capability to learn new things rapidly.
*Wilson has the capability to manage this company.
*The convertible has the capability to reach 100 milometers per hour in just seconds. 敞篷车。。时速到达。。
marine - refer to water. 海军，海里，海上，与海有关的。
mammals - animal that breath air and give birth to their babies.哺乳动物。
echolocation - 回声定位能力，回声定位法。echo- sound get response back.回声
a stream of - a large number of something that one after another.数量多而且连续不断的。一连串的。 如小河流的水，不住地滴流。
cylinder -圆柱

Chat Room:
The width of a human hair.宽度差异很小很小。一根人类头发不到的宽度。
to split hears - refer to "pointless thing"。 意指“为鸡毛蒜皮的事起争执， 为小的不能再小的事去争辩。