Since it has become clear that simulation of the acoustical properties of a room is not successful unless also nonspecular reflections are taken into account, the determination of diffusion and scattering coefficients of boundary profiles is a hot topic in room acoustics research. Measurement of the impulse response of a boundary along a planar array of microphone positions enables us to calculate these coefficients in situ, avoiding the drawbacks of laboratory measurements (necessity of scale modeling, limited value of results for practical situations). Array technology makes it also possible to extrapolate the measured responses to the boundary surface, thus creating an acoustical image of the boundary. Next, scattering objects can be virtually added to this image and the impulse response of the modified configuration at the array position can be obtained by inverse extrapolation. This way, the effect of adding an object to a real environment is simulated in a highly realistic way. For several (virtual) modifications of the original boundary, diffusion and scattering coefficients have been calculated and compared. Also, listening tests have been carried out to assess the perceptual significance of the modifications.@en