Psychoacoustic Characterisation of a Small Fixed-pitch Quadcopter

In this study, a series of acoustic measurements were taken on a small fixed-pitch quadcopter, both in a controlled indoor acoustic environment and while flying outdoors. At controlled indoor conditions, audio signatures were recorded with the quadcopter fixed to a horizontal stand, with 1, 2 and 4 rotor blades operating, and only with the electric motors working. At field conditions, audio signatures were recorded on the ground, varying the relative (lateral) distance and altitude between the quadcopter flight track and the microphone, and the quadcopter payload. Frequency spectra, in the form of narrowband sound-levels, and a series of sound quality metrics (loudness, sharpness, roughness, fluctuation strength and tonality) were calculated from the recorded audio signatures to investigate the specific psychoacoustic characteristics of the small quadcopter under the whole set of experimental conditions tested. On the other hand, at a first step to anticipate potential noise issues of quadcopters operating in urban environments, an objective comparison on the basis of frequency characteristics and sound quality metrics is performed between the small quadcopter and a number of road vehicles and aircraft.