How the Koala Got Its Low Voice 無尾熊的變聲器 The koala makes a sound that should require a bison-size body. A descended larynx gives it an unusually long vocal tract. 一般來說，要發出像無尾熊這麼低沉的叫聲需要像野牛那般大的身體，但是下降的喉頭使 無尾熊有了加長型的聲帶。 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. 動物用牠們管狀的聲帶來發聲，較短的管子可發出較高的頻率，所以像無尾熊這樣逗人喜 愛的小動物應該會發出較高頻率的叫聲。事實上卻不是如此。 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. 一項新的研究顯示，雄性無尾熊發展出這種低沉的求偶叫聲來使雌性對牠們的體型印象深 刻─即使事實上並不然。無尾熊的中低音低到足以從50公分的聲帶來發聲，而這通常是比 野牛還大的動物才會有的構造。 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"] 不過，雄性無尾熊藉由演化出下降的喉頭來發出這種騙人的低音。也就是說，發聲的音箱 在喉嚨的下方。如此使延伸在音箱和嘴巴之間的聲帶加長了，無尾熊便有了更長的發聲管 和低沉的聲音，但是卻沒有笨重的身體。這項發現是由Charlton等人所主導的「雄性無尾 熊（樹袋熊）體型比發聲音箱大解秘：誇大特徵的真相」被刊登在實驗生物學期刊上。 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. 無尾熊的叫聲雖然容易讓人誤以為是由大型動物所發出，但體型較大的雄性無尾熊叫聲倒 真的是比小隻的雄性無尾熊更低沈。這可以幫助雌性無尾熊找到更大隻、更強壯的配偶。 對這些模糊不清的發聲者，大小真是問題啊！ 原文出處： http://www.scientificamerican.com/podcast/episode.cfm?id= how-the-koala-got-its-low-voice-11-09-30 --

※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 114.27.12.229