Transfer functions for different source positions near a plate. Top panel: geometrical arrangement of the plate (black line, view from above in the plate plane). The receiver is indicated as red circle and sound source positions are indicated by colored crosses. Left column: first-order diffraction, BTMS (thin, solid) and UDFA (dashed). Right column: HO-BTMS (15th order) and UDFA with the architecture according to Figure 5, with 1st-order (dashed) and 2nd-order (dotted) crossover. Note that the y-axis scale is magnified in panels c) and d) for improved clarity.