Influence of various uncertainty factors on the result of beamforming measurements

摘要

In a previous publication by Müller-Trapet and Dietrich¹ a virtual measurementrnenvironment for sound-source localization on vibrating structures was presented. Based onrnsurface velocity data obtained from Laser-Scanning-Vibrometry measurements, thernBoundary-Element-Method (BEM) is used to simulate the sound radiation from a vibratingrnplate towards a microphone array under ideal conditions. The advantage of this approachrnis that the measurement conditions can be perfectly controlled and real sources can bernconsidered, without restrictions on the type of source. The virtual measurementrnenvironment will now be used to investigate the effect of some of the uncertainties that canrnbe encountered during beamforming measurements. For the most common planar arrayrngeometries, the beamforming source maps will be calculated for varying signal-to-noisernratios (SNR) and different array imperfections (uncertainties in the location of thernmicrophones and deviation from the omni-directional directivity pattern of thernmicrophones). As a measure of comparison, the two-dimensional normalized crosscorrelationrncoefficient between the ideal source map and the source map with addedrnuncertainties will be evaluated and discussed.