Acoustic effects of drone flights during sudden decelerations

With introduction of U-Spaces into European urban airspaces, unmanned aircraft traffic is expected to increase in the coming years. The growing number of unmanned aircraft, common known as drones, raises the question of the noise impact of these vehicles. So far, this new noise source has only been investigated acoustically in a rudimentary way. The German Environment Agency has, therefore, launched a measurement campaign with various small drone models to investigate acoustic effects. Since drone flights must be designed to be safe, a measurement campaign was conducted in which the models performed a full braking maneuver just before the measurement microphone. This is the case for collision avoidance or when strong gusts of wind occur. In addition, binaural measurements were recorded to provide psychoacoustic findings, as these parameters may be related to the degree of annoyance perceived by the public. In this paper, the measurements and results are presented. Noise levels of the overflights arecompared with noise levels of the deceleration maneuvers. In addition, psychoacoustic quantities such as loudness or sharpness are used and compared for both maneuvers. Finally, conclusions are drawn for the evaluation of drone noise, which can be used for future noise regulations or standardization.