Decoding the Extreme Physics of Ultrasound Generation in the Bat Larynx

频率高达人类声带40倍的超声波呼叫；声音强度：超过喷气发动机的声音强度；声门下压力会把人的喉部撕成碎片；自然界中发现的最高组织速度；对强度和音调的精细控制，足以让任何女高音歌唱家羡慕不已；呼叫速度是最快机枪的两倍。这些能力使回声定位蝙蝠的喉部成为自然界中最极端的声学“乐器”之一。该项目将开发并使用一套科学工具，以全面了解蝙蝠喉部产生超声波的极端物理原理。除了扩展我们对哺乳动物的理解，这种哺乳动物以一种与大多数其他哺乳动物（尤其是人类）根本不同的方式感知世界，目前的研究将探索一个丰富的、耦合的多物理场问题，它位于当前科学能力的最前沿。除了阐明蝙蝠产生超声波的物理原理这一科学进步之外，该项目还将在计算物理学、生物超声波技术、辅助技术、声音功能障碍、动物行为和网络科学等领域产生更广泛的影响。本文建立的空气动力学、组织力学和生物声学耦合计算模型在生物物理和工程中有着广泛的应用。参与该项目的本科生和研究生学员将成为新一代科学家和工程师的一部分，他们可以应用计算、实验方法和跨学科的数据科学来解决最复杂的问题。其研究成果涵盖声学、生物力学、空气动力学、计算物理学、非线性动力学、数据科学和生物生物学等领域。这个项目中的科学主要是由一个首创的、基于图像的、耦合的蝙蝠喉功能的航空组织声学计算模型驱动的。此外，复杂的实验工具，如纳米压痕，微型计算机断层扫描和扫描电子显微镜模型参数化，将被采用。还将进行新的离体实验，以支持这些模型的开发和测试。该项目的具体目标是：(1)对切除发声的蝙蝠喉部的声带动力学和声学进行离体分析；(2)对蝙蝠喉部进行三维成像和生物力学测试，用于模型开发；(3)建立并验证了用于模拟和分析蝙蝠喉部超声发声的气动-组织-声学耦合计算模型；最后(4)利用已验证的航空-组织-声学模型解码超声产生的物理过程。当前项目的主题对高中生和大学生具有内在的吸引力，该小组将利用这一点向更广泛的社区进行广泛的推广。本项目由物理学部生命系统物理学项目和综合有机体系统学部生理机制和生物力学项目共同资助。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Ultrasonic call emissions with frequencies ranging up to 40-times those produced by human vocal cords; sound intensities that exceed that of a jet engine; subglottic pressures that would shred the human larynx to pieces; the highest tissue velocities found anywhere in nature; exquisite control of intensity and tone that would be the envy of any soprano; and call rates that are double that of the fastest machine gun. These are the capabilities that make the larynx of an echolocating bat one of the most extreme acoustic "instruments" in nature. This project will develop and employ a suite of scientific tools to gain a comprehensive understanding of the extreme physics that underlies the generation of ultrasound in the bat larynx. In addition to extending our understanding of a mammal that perceives the world in a way that is fundamentally distinct from most other mammals, particularly humans, the current research will explore a rich, coupled multiphysics problem that lies at the very edge of current scientific capabilities. Beyond the scientific advancement of elucidating the physics of ultrasound generation in bats, the broader impacts of the project span the fields of computational physics, bioinspired ultrasonic technologies, assistive technologies, vocal dysfunction, animal behavior and cyber-enabled science. The coupled aerodynamics, tissue mechanics and bioacoustics computational models developed here have a wide variety of applications in biophysics and engineering. The undergraduate and graduate trainees working on this project will become part of a new generation of scientists and engineers who can apply computation, experimental methods, and data-enabled science across disciplines to solve the most complex problems.The intellectual merits of the research span the areas of acoustics, biomechanics, aerodynamics, computational physics, nonlinear dynamics, data-enabled science and organismal biology. The science in this project is driven primarily by a first-of-its-kind, image-based, coupled aero-tissue-acoustic computational model of bat laryngeal function. In addition, sophisticated experimental tools, such as nano-indentation, micro-Computed Tomography and scanning electron microscopy for model parameterization, will be employed. Novel ex-vivo experiments to support the development and testing of these models will also be conducted. The specific objectives of the projects are (1) conduct ex-vivo analysis of vocal fold dynamics and acoustics in a vocalizing excised bat larynx; (2) conduct 3D imaging and biomechanical testing of a bat larynx for model development; (3) develop and validate a coupled aero-tissue-acoustics computational model for simulation and analysis of ultrasonic vocalization in the bat larynx; and finally (4) decode the physics of ultrasound generation using the validated aero-tissue-acoustic model. The topic of the current project has inherent appeal to high-school and university students, and the group will leverage this for a broad outreach to the wider community. This project is jointly funded by the Physics of Living Systems Program in the Division of Physics and the Physiological Mechanisms and Biomechanics Program of the Division of Integrative Organismal Systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.