Acoustic source localisation using vibroacoustic beamforming

Abstract

For acoustic source localisation in a fluid, sound pressure is traditionally measured using a microphone array, and acoustic beamforming is then applied to the pressure signals to localise the source. However, in some engineering applications, it is not feasible to place the microphone/hydrophone array in the fluid to localise an acoustic source. Hence, this work proposes a vibroacoustic beamforming for sound source localisation which applies the beamforming procedure to the measured vibration signals at the surface of a structure in contact with the fluid in which the acoustic source is located. To evaluate the localisation performance of the proposed method, a numerical study is conducted to localise a monopole source in a room using vibration data obtained from an elastic panel on the room wall. To simulate more realistic situation, different levels of signal to noise ratio are considered by moving the source away from the wall-mounted sensors and consequently altering the direct acoustic field (signal). Moreover, commonly used frequency domain beamforming techniques namely conventional beamforming, functional beamforming, minimum variance distortionless response and minimum power distortionless response are applied to the measured signals to localise the source. The performance of each technique is then evaluated by comparing the beamforming output obtained from vibroacoustic beamforming with that of acoustic beamforming and by quantifying the dynamic range and spatial resolution for each method. It can be concluded that vibroacoustic beamforming can be used for acoustic localisation as an alternative to the acoustic beamforming.