How the Koala Got Its Low Voice 无尾熊的变声器 The koala makes a sound that should require a bison-size body. A descended larynx gives it an unusually long vocal tract. 一般来说，要发出像无尾熊这麽低沉的叫声需要像野牛那般大的身体，但是下降的喉头使 无尾熊有了加长型的声带。 To vocalize, animals create sound waves in their pipe-like vocal tracts. Shorter pipes produce higher-frequency sounds, so small animals like the cuddly koala should have high voices. [koala sound] Or not. 动物用牠们管状的声带来发声，较短的管子可发出较高的频率，所以像无尾熊这样逗人喜 爱的小动物应该会发出较高频率的叫声。事实上却不是如此。 A new study suggests that male koalas developed this low mating call to impress females with their size—even if they’re not quite as large as their bellows boast. The koala’s baritone is low enough to come from a 50-centimeter pipe, which should require a body larger than a bison. 一项新的研究显示，雄性无尾熊发展出这种低沉的求偶叫声来使雌性对牠们的体型印象深 刻─即使事实上并不然。无尾熊的中低音低到足以从50公分的声带来发声，而这通常是比 野牛还大的动物才会有的构造。 Instead, males developed deceptively low voices by evolving a descended larynx, which means the voice box sits lower in the throat. This lengthens the vocal tract, which stretches between voice box and mouth, giving the koala a longer “pipe” and lower voice without a bigger body. The finding is in the Journal of Experimental Biology. [Benjamin Charlton et al., "Cues to body size in the formant spacing of male koala (Phascolarctos cinereus) bellows: Honesty in an exaggerated trait"] 不过，雄性无尾熊藉由演化出下降的喉头来发出这种骗人的低音。也就是说，发声的音箱 在喉咙的下方。如此使延伸在音箱和嘴巴之间的声带加长了，无尾熊便有了更长的发声管 和低沉的声音，但是却没有笨重的身体。这项发现是由Charlton等人所主导的「雄性无尾 熊（树袋熊）体型比发声音箱大解秘：夸大特徵的真相」被刊登在实验生物学期刊上。 Koala calls may be misleading, but larger males have even lower voices than their runtier counterparts. Which allows females to identify bigger, stronger mates. To these fuzzy bellowers, size does matter. 无尾熊的叫声虽然容易让人误以为是由大型动物所发出，但体型较大的雄性无尾熊叫声倒 真的是比小只的雄性无尾熊更低沈。这可以帮助雌性无尾熊找到更大只、更强壮的配偶。 对这些模糊不清的发声者，大小真是问题啊！ 原文出处： http://www.scientificamerican.com/podcast/episode.cfm?id= how-the-koala-got-its-low-voice-11-09-30 --

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