Acoustic beamforming: analysis of uncertainty and metrological performances

In this paper, the metrological performances of the acoustic beamforming technique have been investigated, and in
particular, its accuracy in estimating the acoustic power of sources and in localizing their spatial position has been
analysed.
The uncertainty of the system has been determined combining the statistical effects of input parameters uncertainty
under the basic hypothesis that the sound source can be represented as a distribution of independent monopoles. This
analysis was performed using a Type B approach based on an analytical model according to the ISO Guide of the
expression of uncertainty in measurement and subsequently using a numerical model based on Monte Carlo simulation.
Systematic errors due to deviations of input parameters (e.g. speed of sound or source–array distance), affecting output
level and spatial accuracy have been analysed. Once these inaccuracies were quantified, suggestions to minimize them were
given.
Finally a criterion to optimize focussing of the beamforming technique based on acoustic image contrast maximization
has been developed.