Department of Communication Sciences and Disorders, The University of Iowa, Iowa City, IA 52242, USA.
J Exp Biol. 2010 Nov 15;213(Pt 22):3866-73. doi: 10.1242/jeb.044982.
Despite the functional importance of loud, low-pitched vocalizations in big cats of the genus Panthera, little is known about the physics and physiology of the mechanisms producing such calls. We investigated laryngeal sound production in the laboratory using an excised-larynx setup combined with sound-level measurements and pressure-flow instrumentation. The larynges of five tigers (three Siberian or Amur, one generic non-pedigreed tiger with Bengal ancestry and one Sumatran), which had died of natural causes, were provided by Omaha's Henry Doorly Zoo over a five-year period. Anatomical investigation indicated the presence of both a rigid cartilaginous plate in the arytenoid portion of the glottis, and a vocal fold fused with a ventricular fold. Both of these features have been confusingly termed 'vocal pads' in the previous literature. We successfully induced phonation in all of these larynges. Our results showed that aerodynamic power in the glottis was of the order of 1.0 W for all specimens, acoustic power radiated (without a vocal tract) was of the order of 0.1 mW, and fundamental frequency ranged between 20 and 100 Hz when a lung pressure in the range of 0-2.0 kPa was applied. The mean glottal airflow increased to the order of 1.0 l s(-1) per 1.0 kPa of pressure, which is predictable from scaling human and canine larynges by glottal length and vibrational amplitude. Phonation threshold pressure was remarkably low, on the order of 0.3 kPa, which is lower than for human and canine larynges phonated without a vocal tract. Our results indicate that a vocal fold length approximately three times greater than that of humans is predictive of the low fundamental frequency, and the extraordinarily flat and broad medial surface of the vocal folds is predictive of the low phonation threshold pressure.
尽管在 Panthera 属的大型猫科动物中，响亮、低沉的发声对于功能至关重要，但对于产生这些叫声的机制的物理学和生理学却知之甚少。我们使用离体喉模型结合声级测量和压力-流量仪器在实验室中研究了喉声产生。五年期间，奥马哈亨利多利动物园(Henry Doorly Zoo)提供了五只老虎（三只西伯利亚或东北虎，一只普通非纯种老虎，有孟加拉虎血统，一只苏门答腊虎）的喉，这些老虎均因自然原因死亡。解剖学研究表明，声门的杓状软骨部分既有一个刚性的软骨板，也有一个与室带融合的声带。这两个特征在之前的文献中都被混淆地称为“声带”。我们成功地在所有这些喉中诱导出了发声。我们的结果表明，所有标本的声门气流功率约为 1.0 W，无声道辐射的声功率约为 0.1 mW，当施加 0-2.0 kPa 范围内的肺压时，基频范围在 20-100 Hz 之间。平均声门气流增加到约 1.0 l s(-1)每 1.0 kPa 的压力，这可以通过将人类和犬科动物的喉按声门长度和振动幅度进行缩放来预测。发声阈值压力非常低，约为 0.3 kPa，低于无声道发声的人类和犬科动物的喉。我们的结果表明，声带长度大约是人类的三倍预测到低频，而声带非常平坦和宽阔的内侧表面则预测到低发声阈值压力。
