The Sound Suppression Characteristics of Wing Feather of Owl (Bubo bubo)

Many species of owls are able to fly noiselessly, and their wing feathers play an important role for the silent flight. In this paper, we studied the sound suppression mechanism of the eagle owl (Bubo bubo) by Stereo Microscope (SM), Scanning Electron Microscopy (SEM) and Laser Scanning Confocal Microscope (LSCM). To investigate the effects of special characteristics of wing feather on owl silent flight, the acoustic properties, including the sound absorption coefficient and flight noise, were compared between the eagle owl and common buzzard (Buteo buteo). The results show that the eagle owl generates lower noise than common buzzard during flight, and its wing feather has better sound absorption properties. The leading edge serration and trailing edge fringe can improve the pressure fluctuation of turbulence boundary, and suppress the generation of vortex sound. The elongated distal barbules form a multi-layer grid porous structure which also has an effect on sound absorption. This research not only can give the inspiration for solving the aerodynamic noise of aircraft and engineering machine, but also can provide a new idea for the design of low-noise devices.