The use of interpolated time-domain equivalent source method for reconstruction of semi-free transient sound field

Abstract

A semi-free transient sound field is reconstructed by extending the interpolated time-domain equivalent source method (ITDESM) in the free field to the semi-free field. In this approach, the time-domain equivalent sources are placed not only near the actual sound sources, but also in the vicinity of their mirrored sources with respect to the reflecting plane surface. Suppose that the number of equivalent sources distributed around the mirrored sources (virtual equivalent sources) is the same as that used near the actual sources (actual equivalent sources), with their locations symmetrical about the reflecting surface. The reflecting surface considered here can be perfectly rigid as well as impedance-effected. Furthermore, by reformulating the strengths of the virtual equivalent sources at each time instant with those of the corresponding actual equivalent sources, the computation load of solving the equivalent source strengths can be reduced by 50%. Numerical examples of reconstructing the semi-free transient sound field radiated from three monopoles under different reflection conditions demonstrate the feasibility of the proposed method.