THE EFFECTS OF TRACHEAL COILING ON THE VOCALIZATIONS OF CRANES (AVES, GRUIDAE)
THE EFFECTS OF TRACHEAL COILING ON THE VOCALIZATIONS OF CRANES (AVES, GRUIDAE)
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DOI：
10.1007/bf00609454
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发表时间：
1987-01-01
影响因子：
2.1
通讯作者：
WASSER, JS
中科院分区：
文献类型：
--
作者：
GAUNT, AS;GAUNT, SLL;WASSER, JS
人们普遍认为，许多鸟类的细长、通常卷曲的气管是为了发出响亮、有穿透力的叫声而适应的。一个推论的假设是，声学效果是由细长管的共振特性产生的，将鸟类比作管乐器。我们对几种具有不同程度的气管盘绕的起重机进行了实验。无论卷绕程度如何，所有起重机都可以使用极低的驱动压力发出极大的声音。气管的手术改造或将呼吸气体改为氦氧都没有产生一致的声音变化，而这种变化可以明确地归因于输卵管共振的变化。然而，缩短气管会显着降低声音强度，降低的程度大致与缩短的程度成正比。尽管这种减少的部分原因可能是由于管外孔处的阻抗失配增加，还有一些是由于直接来自气管硬壁的辐射减少，但这些解释几乎无法解释我们观察到的巨大影响。因此，我们假设了一种更不寻常的机制：嵌入血清中的气管线圈的功能类似于弦乐器的琴桥，将微小声源的振动传递到大型辐射表面，即胸骨。然后，胸骨在鸟类气囊系统的大型内部空气储存器上振动。由于胸骨形状复杂，因此会产生多种共振，并对多种频率做出反应；作为固体振荡器，其共振不会受到低密度气体的太大影响。因此，我们建议将鹤和其他气管增大的鸟类类比为小提琴，而不是长号。
It is generally supposed that the elongated, often coiled tracheae of many species of birds are adaptations for the production of loud, penetrating calls. A corollary supposition is that the acoustic effects are produced by the resonant properties of the elongated tube, with the birds being analogized to a wind instrument. We have experimented with several species of cranes possessing different degrees of tracheal coiling. Regardless of the degree of coiling, all cranes can utter extremely loud calls using remarkably low driving pressures. Neither surgical modifications of the trachea nor changing the respiratory gases to helium-oxygen produced consistent changes of voice that could be unambiguously attributed to changes of tubal resonances. However, shortening the trachea markedly reduced vocal intensity, the degree of reduction being roughly proportional to the degree of shortening. Although some of that reduction may derive from an increased impedance mismatch at the external aperture of the tube, and some from a decreased radiation directly from the hard walls of the trachea, these explanations scarcely account for the dramatic effects we observed. We, therefore, hypothesize a more unusual mechanism: The tracheal coils that are embedded in the serum serve a function analogous to the bridge of a stringed instrument, transmitting the vibrations of a tiny sound source to a large radiating surface, the sternum. The sternum then vibrates against the large internal air reservoir of the avian airsac system. As it has a complex shape, the sternum will have many resonances and will respond to many frequencies; as a solid oscillator, its resonances will not be greatly affected by low density gases. Hence, we suggest that cranes and other birds with enlarged windpipes are more properly analogized with a violin than a trombone.