Department of Evolution, Ecology, and Organismal Biology, Spieth Hall, University of California, Riverside, CA 94720, USA.
Department of Mechanical Engineering and Mechanics, Packard Laboratory, Lehigh University, Bethlehem, PA 18015, USA.
Integr Comp Biol. 2020 Nov 1;60(5):1025-1035. doi: 10.1093/icb/icaa128.
Animal wings produce an acoustic signature in flight. Many owls are able to suppress this noise to fly quietly relative to other birds. Instead of silent flight, certain birds have conversely evolved to produce extra sound with their wings for communication. The papers in this symposium synthesize ongoing research in "animal aeroacoustics": the study of how animal flight produces an acoustic signature, its biological context, and possible bio-inspired engineering applications. Three papers present research on flycatchers and doves, highlighting work that continues to uncover new physical mechanisms by which bird wings can make communication sounds. Quiet flight evolves in the context of a predator-prey interaction, either to help predators such as owls hear its prey better, or to prevent the prey from hearing the approaching predator. Two papers present work on hearing in owls and insect prey. Additional papers focus on the sounds produced by wings during flight, and on the fluid mechanics of force production by flapping wings. For instance, there is evidence that birds such as nightbirds, hawks, or falcons may also have quiet flight. Bat flight appears to be quieter than bird flight, for reasons that are not fully explored. Several research avenues remain open, including the role of flapping versus gliding flight or the physical acoustic mechanisms by which flight sounds are reduced. The convergent interest of the biology and engineering communities on quiet owl flight comes at a time of nascent developments in the energy and transportation sectors, where noise and its perception are formidable obstacles.
动物的翅膀在飞行中会产生声学特征。许多猫头鹰能够抑制这种噪音，从而比其他鸟类更安静地飞行。有些鸟类并没有安静地飞行，而是相反地进化出了用翅膀发出额外的声音来进行交流。本次研讨会的论文综合了正在进行的“动物空气声学”研究：研究动物飞行如何产生声学特征、其生物学背景以及可能的生物启发工程应用。三篇论文介绍了关于捕蝇鸟和鸽子的研究，强调了继续揭示鸟类翅膀如何发出通讯声音的新物理机制的工作。安静的飞行是在捕食者-猎物相互作用的背景下进化而来的，要么帮助像猫头鹰这样的捕食者更好地听到猎物的声音，要么防止猎物听到接近的捕食者的声音。两篇论文介绍了猫头鹰和昆虫猎物的听觉研究。其他论文则侧重于翅膀在飞行中产生的声音，以及翅膀拍打产生力的流体力学。例如，有证据表明，像夜鹰、鹰或隼这样的鸟类也可能有安静的飞行。由于尚未充分探索，蝙蝠的飞行似乎比鸟类的飞行更安静。一些研究途径仍然存在，包括扑翼飞行和滑翔飞行的作用，或飞行声音减小的物理声学机制。生物学和工程界对安静的猫头鹰飞行的共同兴趣，正值能源和交通部门新兴发展之际，而噪音及其感知是这些领域面临的巨大障碍。
