Influence of various uncertainty factors on the result of beamforming measurements

In a previous publication by the authors, a virtual measurement environment for sound-source localization on vibrating structures was presented. Based on surface velocity data obtained from Laser-Scanning-Vibrometry measurements, the Boundary-Element-Method (BEM) is used to simulate the sound radiation from a vibrating plate towards a microphone array under ideal conditions. The advantage of this approach is that the measurement conditions can be perfectly controlled and real sources can be considered, without restrictions on the type of source. The virtual measurement environment will now be used to investigate the effect of some of the uncertainties that can be encountered during beamforming measurements. For the most common planar array geometries, the beamforming source maps will be calculated for varying Signal-to-Noise Ratios (SNR) and different array imperfections (uncertainties in the microphone locations and deviation from the omni-directional directivity pattern of the microphones). As a measure of comparison, the two-dimensional normalized cross-correlation coefficient between the ideal source map and the source map with added uncertainties will be evaluated and discussed.