Multi-rotor Unmanned Aerial Vehicles (UAVs) are developing rapidly recently in usage and popularity in civil applications. However, although the great benefits UAVs have brought, their noise pollution is one of the concerns with their proliferation. The two main noise sources of a UAV are the motors and propellers. And the propellers are often assumed to be the dominant noise source in the literature, hence noise reduction of propeller becomes research focus; however, recent studies suggest that the contribution from the motor may also be important. This paper explore a passive noise reduction approach based on micro-perforated panel (MPP) absorbers together with sound-proof materials. Experimental results show that the proposed noise reduction constructions can have a significant reduction to the motor's overall noise level.

近来，多旋翼无人机（UAV）在民用领域的使用和普及方面发展迅速。然而，尽管无人机带来了巨大的好处，但其噪声污染却是其扩散所关注的问题之一。无人机的两个主要噪声源是电动机和螺旋桨。而且螺旋桨在文献中经常被认为是主要的噪声源，因此螺旋桨的降噪成为研究的重点。但是，最近的研究表明，电动机的贡献也可能很重要。本文探索了一种基于微孔板（MPP）吸收器和隔音材料的无源降噪方法。实验结果表明，所提出的降噪结构可以显着降低电动机的整体噪声水平。