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Dolphins Dumb Down Calls to Compete with Ship Noise

The oceans are getting louder. And coastal¹ areas are some of the noisiest, as in this underwater recording², captured 17 miles off the coast of Ocean City, Maryland.

海洋的声音越来越大。在这段水下录音中，沿海地区马里兰是最嘈杂的地区之一。

The noise could be a problem for marine³ mammals, which, like us, use sound to communicate. "Just like if we're in a noisy bar, we have to shout to each other, they might have to do that too." Helen Bailey is a marine biologist at the University of Maryland Center for Environmental Science.

噪音可能是海洋哺乳动物的一个问题，它们和我们一样，使用声音进行交流。“就像我们在一个嘈杂的酒吧里，我们必须互相大喊大叫，他们可能也会这样做。”海伦?贝利是马里兰大学环境科学中心的海洋生物学家。

She and her colleagues recorded two months of underwater sounds, in that same area off the coast of Maryland. They used automated⁴ software to fish out 200 bottlenose dolphin whistles from the noise, and visually compared the spectrograms. Here's a normal whistle.

她和同事在马里兰州海岸附近的同一海域录下了两个月的水下声音。他们使用自动化软件从噪音中找出200个宽吻海豚的哨声，并对光谱图进行视觉比较。这是正常的哨子。

But what they found was that dolphins dumbed down the complexity⁵ of their whistles and raised their pitch, when they were competing with shipping⁶ noise. Which apparently⁷ helps, but could also hurt, their ability to communicate."By using simpler calls, yes, there is a risk they're not communicating as much information as they would if it was quieter. Also for younger dolphins they actually learn these sounds from hearing other dolphins. So they're hearing this much simpler language."

但他们发现，海豚在与船舶噪音竞争时，降低了哨声的复杂性，提高了音调。这显然对他们有利，但也可能伤害他们的沟通能力。“通过使用更简单的通话，是的，他们可能没有像在安静点的情况下那样交流那么多信息。”对于年轻的海豚来说，他们实际上是通过听其他海豚的声音来学习这些声音的。所以他们听到的是更简单的语言。

The results—and a few of those spectrograms—are in the journal Biology Letters. [Leila Fouda et al., Dolphins simplify their vocal⁸ calls in response to increased ambient noise]The survey site is the proposed future home of a wind farm - which could mean lots of noise as the huge towers are installed. Until then, it's the chronic⁹ roar of ships and boats that Bailey wants people to ponder. "I think people think about boats in terms of the emissions¹¹, just like with cars. And I think what we need to think about is sound is also an emission¹⁰."

研究结果发表在《生物学快报》杂志上。调查地点是未来风力发电厂的所在地，这可能意味着，安装巨型塔时会有很多噪音。在那之前，贝利希望人们思考的是，船和船的慢性轰鸣声。“我认为，人们从排放的角度来考虑船只，就像汽车一样。我认为我们需要考虑的是声音，这也是一种发射物。