The PAC-MAN geometry is the two-dimensional equivalent to the three-dimensional cat’s eye geometry. As shown in Fig. 1, it is a circle of radius with an angular cut-out ranging from (measured from the x-axis) and. An analytical solution of the sound field inside the cut-out and outside the PAC-MAN has been derived in Ziegelwanger-Reiter-JCP. The PAC-MAN problem is suited for radiation and scattering. The description with references can be found in the PDF. H. Ziegelwanger and P. Reiter, Analytic formulation of radiated and scattered sound, can be found in the ZIP file.