RESUMEN
In conventional delay-and-sum beamforming, the monopole source assumption may cause a dipole source to be misinterpreted, leading to incorrect mapping results. A dipole-based beamforming method is proposed that is an extension of monopole-based conventional beamforming. The dipole sources could be located with no prior knowledge of the source orientation, and the unknown orientation is arbitrary in a three-dimensional domain. The location of a dipole source is determined by calculating the beamforming results at predefined orientations and positions using a dipole-based propagation function, and the final beamforming result at each scanning point is determined by the maximum value at the predefined orientations. Numerical simulations and experiments are performed on rotating dipole sources, and satisfactory results for the location of these dipole sources are obtained with different orientations.
RESUMEN
An acoustic source identification technique with single layer pressure measurement is presented to reconstruct normal velocities of target sources in noisy environments. The theory for this reconstruction is developed from the inverse patch transfer functions method which is supposed to combine measurements of pressure and velocity on a surface surrounding the source. The rigid microphone array is called an acoustic mask, which is designed to obtain pressure on the Neumann boundary condition and realized by microphones flush mounted on the aluminum plate. The validity of the proposed method is demonstrated by giving the normal velocities of two baffled loudspeakers in a noisy environment in the simulation and experiment. Another experiment of a clamped steel plate is further presented to illustrate the ability of the acoustic mask to obtain the partial velocity field of interest without reconstruction of the whole source surface velocity. The accuracy of this technique is demonstrated by comparison with the accelerometer method.
