Noise measurement of a quadrotor drone in an anechoic chamber

Abstract

Operation of drones near densely populated urban areas can cause significant noise pollution issues. Drone noise measurements in controllable environments are essential for noise certification. This study presents experimental measurement results of the noise radiated from a quadrotor drone at various working conditions. The experiment was conducted in an anechoic chamber. The noise was measured by microphone arrays with a total of 15 free-field microphones. The instantaneous position of the drone was recorded by an optical motion capture system. A criterion on the measurement distance to ensure acoustic far-field condition is proposed and justified by the measurement results. Noise directivity maps on a spherical surface were reconstructed using the microphone array data at different observer angles. Correlations were found between the directivity pattern and the airframe geometry. Additionally, the effect of loading on noise was analyzed through parametric tests in which the drone was loaded with additional mass. The unbalanced loading case was also considered. For each test condition, multiple tests were conducted to reduce the statistical errors and uncertainties of the measurements, and the results present high repeatability.