Modeling of transient scattered field

The spatial impulse response approach has been used to formulate an analytical model which could be helpful in predicting transient distortion by rigid scattering objects with regular/simple forms. The transient field is obtained as a linear convolution of the spatial impulse response (related to the Huygen’s construction and object’s geometry) with the free-field acoustic signal. The time-domain description is attractive since it allows for an easy separation of the incident and scattered field, for a strict representation of the wavefront and it may also allow for a closed—rather than integral—form of the solution for the scattered wave. Experimental results in which transients scattered by a large metal sheet were recorded at various positions near its edge in an anechoic chamber and which are in agreement with the classical harmonic integral description have been compared with approximate transient solutions obtained for a rigid half-plane scatterer. Possible closed-form solutions for the above scatterer are also discussed and related to the boundary conditions concluded from the experiment. [Acknowledgments: to Professor Harry Green for his intellectual support of this research and to Professor Richard Thorn for his long-term support and advice.]