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科学美国人60秒 SSS 蓝鲸歌声的声调发生变化

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蓝鲸歌声的声调发生变化

This is Scientific American — 60-Second Science. I'm Christopher Intagliata.

Blue whales are the largest animals ever to exist on Earth. But they're still tough to track. Because they live underwater where we can't easily see them — and often in remote areas, like the southern ocean. But the whales' songs can travel hundreds of kilometers underwater... so scientists often listen for them instead. (blue whale call) By the way, that's sped up 10 times so you can hear it.

Over the years these eavesdropping1 biologists have noticed a mysterious trend: that certain blue whale calls are gradually lowering in pitch, over time. For example, here's a call from 2002, followed by one from 2017. (2002–2017 call)

"It has been observed in blue whale populations worldwide. So this phenomenon has to have a worldwide explanation." Emmanuelle Leroy is a bioacoustician at the University of New South Wales in Australia. She did the work at the University of Brest in France.

Her team confirmed the phenomenon holds true for populations of blue whales in the southern Indian Ocean, too. And they suggest one reason may be that whale numbers have rebounded3 from the days of Captain Ahab. More whales means individuals don't have to shout as loud to be heard by other whales. And because of an anatomical peculiarity4 in the way whales sing, the softer they sing, the lower the pitch.

The scientists have another theory, too, which may be acting5 i?n concert with the first: which is that whales are singing more softly—and therefore more deeply—because increasingly acidic ocean waters carry their calls farther. The full write-up is in the Journal of Geophysical Research: Oceans.

Leroy and her team noticed one other short-term trend: that southern blue whales' songs actually get higher in pitch during the Austral summer. Perhaps in an effort to be heard over cracking icebergs7.

"Like when you put an ice cube in your drink, you can hear it crack. So it's the same for an iceberg6 — so it will be really loud and you can hear it across an oceanic basin."

To solve these mysteries more definitively8, the scientists say that we'll need to keep listening, and monitor the changing chemical and acoustic2 properties of the oceans. To see which of these ideas are borne out. And which don't hold water.

Thanks for listening for Scientific American — 60-Second Science. I'm Christopher Intagliata.


点击收听单词发音收听单词发音  

1 eavesdropping 4a826293c077353641ee3f86da957082     
n. 偷听
参考例句:
  • We caught him eavesdropping outside the window. 我们撞见他正在窗外偷听。
  • Suddenly the kids,who had been eavesdropping,flew into the room. 突然间,一直在偷听的孩子们飞进屋来。
2 acoustic KJ7y8     
adj.听觉的,声音的;(乐器)原声的
参考例句:
  • The hall has a fine acoustic.这个大厅的传音效果很好。
  • Animals use a whole rang of acoustic, visual,and chemical signals in their systems of communication.动物利用各种各样的听觉、视觉和化学信号来进行交流。
3 rebounded 7c3c38746f183ba5eac1521bcd358376     
弹回( rebound的过去式和过去分词 ); 反弹; 产生反作用; 未能奏效
参考例句:
  • The ball rebounded from the goalpost and Owen headed it in. 球从门柱弹回,欧文头球将球攻进。
  • The ball rebounded from his racket into the net. 球从他的球拍上弹回网中。
4 peculiarity GiWyp     
n.独特性,特色;特殊的东西;怪癖
参考例句:
  • Each country has its own peculiarity.每个国家都有自己的独特之处。
  • The peculiarity of this shop is its day and nigth service.这家商店的特点是昼夜服务。
5 acting czRzoc     
n.演戏,行为,假装;adj.代理的,临时的,演出用的
参考例句:
  • Ignore her,she's just acting.别理她,她只是假装的。
  • During the seventies,her acting career was in eclipse.在七十年代,她的表演生涯黯然失色。
6 iceberg CbKx0     
n.冰山,流冰,冷冰冰的人
参考例句:
  • The ship hit an iceberg and went under.船撞上一座冰山而沉没了。
  • The glacier calved a large iceberg.冰河崩解而形成一个大冰山。
7 icebergs 71cdbb120fe8de8e449c16eaeca8d8a8     
n.冰山,流冰( iceberg的名词复数 )
参考例句:
  • The drift of the icebergs in the sea endangers the ships. 海上冰山的漂流危及船只的安全。 来自《简明英汉词典》
  • The icebergs towered above them. 冰山高耸于他们上方。 来自辞典例句
8 definitively bfa3c9e3e641847693ee64d5d8ab604b     
adv.决定性地,最后地
参考例句:
  • None of the three super-states could be definitively conquered even by the other two in combination. 三个超级国家中的任何一国都不可能被任何两国的联盟所绝对打败。 来自英汉文学
  • Therefore, nothing can ever be definitively proved with a photograph. 因此,没有什么可以明确了一张照片。 来自互联网
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TAG标签:   科学美国人60秒  英语听力  sss
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