Herbst Christian T, Elemans Coen P H
Bioacoustics Laboratory, Department of Cognitive Biology, University of Vienna , Vienna, Austria.
Department of Communication Sciences and Disorders, College of Liberal Arts and Sciences, University of Iowa , Iowa, IA USA.
Philos Trans R Soc Lond B Biol Sci. 2025 Apr 3;380(1923):20240006. doi: 10.1098/rstb.2024.0006.
Among air-breathing tetrapods, the most common sound production mechanism is flow-induced self-sustained tissue oscillation, aka voiced sound production, driven by inherently nonlinear physical processes. Some signature features like deterministic chaos have received particular attention in bioacoustics as nonlinear phenomena (NLP). However, one type of NLP that extends frequency ranges and enriches timbres has received much less focus in comparative bioacoustics: vocal registers. Controlled by muscle activity, vocal registers constitute distinct periodic vibratory states of vocal tissues. Transitions between vocal registers often lead to abrupt fundamental frequency jumps, which are, e.g., deliberately used in human alpine yodelling, for example. Theoretical work suggests that register transitions are caused by saddle-node-in-limit-cycle bifurcations. Here, we review the biophysical underpinnings of vocal registers and what signatures they leave in vocal fold kinematics and acoustics in the best studied species: humans. Apart from human speech and song, registers have been described only in a few animal taxa, but the occurrence of signature features suggests that vocal registers could be much more common across vertebrates than currently appreciated. We suggest that registers are a fundamental trait of voice production and that they are favoured in selection because they vastly extend and diversify the acoustic signalling space. This article is part of the theme issue 'Nonlinear phenomena in vertebrate vocalizations: mechanisms and communicative functions.'
在呼吸空气的四足动物中，最常见的发声机制是由内在非线性物理过程驱动的气流诱导自维持组织振荡，即浊音发声。一些标志性特征，如确定性混沌，作为非线性现象（NLP）在生物声学中受到了特别关注。然而，一种扩展频率范围并丰富音色的非线性现象在比较生物声学中受到的关注要少得多：声区。声区由肌肉活动控制，构成声带组织不同的周期性振动状态。例如，声区之间的转换通常会导致基频突然跳跃，人类高山约德尔唱法就故意利用了这一点。理论研究表明，声区转换是由极限环中的鞍结分岔引起的。在这里，我们回顾了声区的生物物理基础，以及它们在研究最充分的物种——人类的声带运动学和声学中留下的特征。除了人类的言语和歌曲，声区仅在少数动物类群中被描述过，但标志性特征的出现表明，声区在脊椎动物中的普遍程度可能比目前所认识到的要高得多。我们认为，声区是发声的一个基本特征，它们在选择中受到青睐，因为它们极大地扩展了声学信号空间并使其多样化。本文是主题为“脊椎动物发声中的非线性现象：机制与交流功能”的一部分。
