Design of an unmanned aerial vehicle mounted system for quiet audio recording

This paper describes the design of an unmanned aerial vehicle (UAV) mounted system for recording sound from a targeted source or direction with a minimum amount of noise. The objective of the study is: i) select an optimum electric motor-propeller combination which minimises the level of unwanted noise from these components at the microphone positions; ii) design a microphone array configuration suitable for installation on a UAV; and iii) develop a signal processing algorithm that significantly reduces noise in the recording. The designed system was prototyped and tested in various scenarios simulated in an anechoic chamber as well as by recordings collected from a system mounted on a hovering UAV. The system succeeded in reducing the propeller noise level up to approximately 12 dB compared to the recording by a shotgun microphone. Results of subjective listening tests suggest the quality of the recording made by the designed UAV mounted system is significantly better than that of the recording by the shotgun microphone.