A two‐dimensional scalar model has been established to study the scattering caused by an inhomogeneous medium with granular microstructure. Time domain signals are calculated using a 64‐node PC cluster. Special test problems are set up to compare the effects of single and multiple scattering and to quantify errors introduced by the Born approximation. Computed results for backscattered RMS grain noise results are compatible with recent experimental measurements. © 2003 American Institute of Physics