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For many potential entrée animals this is one of the scariest sounds around. Scientists long thought the lion's distinctive¹ roar was due to thick layers of fat inside the vocal² cords. But new research suggests that it's not the fat that makes the roar, it's the shape of the vocal cords themselves.

Most animals have triangular³ vocal cords. But the lion's mighty⁴ pipes are square. Tigers' too. That square shape allows the tissue to withstand more stretching, which lets the big cats create louder roars using lower lung pressure. The finding is the journal Public Library of Science ONE.

When we say loud, we mean loud. Lion roars can travel over five miles, and reach up to 114 decibels⁵, which is as loud as a jet airplane taking off. The researchers suggest that the fat is there to cushion the cords, and to provide tissue for repair if the cords get damaged.

Understanding how that repair happens might help doctors fix damaged vocal cords in humans, too. Which would have to be called a roaring success.

Thanks for the minute. For Scientific American's 60-Second Science, I'm Rose Eveleth.

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收听单词发音

1 distinctive
adj.特别的，有特色的，与众不同的
参考例句：
She has a very distinctive way of walking.她走路的样子与别人很不相同。 This bird has several distinctive features.这个鸟具有几种突出的特征。

2 vocal
adj.直言不讳的；嗓音的；n.[pl.]声乐节目
参考例句：
The tongue is a vocal organ.舌头是一个发音器官。 Public opinion at last became vocal.终于舆论哗然。

3 triangular
adj.三角（形）的，三者间的
参考例句：
It's more or less triangular plot of land.这块地略成三角形。 One particular triangular relationship became the model of Simone's first novel.一段特殊的三角关系成了西蒙娜第一本小说的原型。

4 mighty
adj.强有力的；巨大的
参考例句：
A mighty force was about to break loose.一股巨大的力量即将迸发而出。 The mighty iceberg came into view.巨大的冰山出现在眼前。

5 decibels
n.分贝( decibel的名词复数 )
参考例句：
The typical lawn mower makes about 90 decibels of noise. 典型的割草机发出的声响约为90分贝。来自《简明英汉词典》 A normal conversation reaches 55 decibels. 普通的谈话即可达55分贝。来自《简明英汉词典》