How oscillating aerodynamic forces explain the timbre of the hummingbird’s hum and other animals in flapping flight

eLife

Patrick WA Wijnings¹  Rick Scholte²  Jade Nguyen³  David Lentink³  Ben J Hightower³  Daniel Shorr³  Rivers Ingersoll³  Diana D Chin³ 

[1] Electrical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands;Engineering, Sorama, Eindhoven, Netherlands;Mechanical Engineering, Stanford University, Stanford, United States;

关键词: bioacoustic;    behavior;    flapping wing;    flying animals;    insects, birds;    bats;    Calypte anna;    Other;   

DOI  :  10.7554/eLife.63107

来源: eLife Sciences Publications, Ltd

【 摘 要 】

How hummingbirds hum is not fully understood, but its biophysical origin is encoded in the acoustic nearfield. Hence, we studied six freely hovering Anna’s hummingbirds, performing acoustic nearfield holography using a 2176 microphone array in vivo, while also directly measuring the 3D aerodynamic forces using a new aerodynamic force platform. We corroborate the acoustic measurements by developing an idealized acoustic model that integrates the aerodynamic forces with wing kinematics, which shows how the timbre of the hummingbird’s hum arises from the oscillating lift and drag forces on each wing. Comparing birds and insects, we find that the characteristic humming timbre and radiated power of their flapping wings originates from the higher harmonics in the aerodynamic forces that support their bodyweight. Our model analysis across insects and birds shows that allometric deviation makes larger birds quieter and elongated flies louder, while also clarifying complex bioacoustic behavior.

【 授权许可】

CC BY