Ri 1[m] Inner sphere radius Rpml 0.5[m] PML layer thickness Rfar 10[m] Far-field evaluation distance f0 1000[Hz] Driving frequency c0 1500[m/s] Speed of sound lambda0 c0/f0 Wave length A 0.5[m] x-semiaxis ellipsoid B 0.25[m] y-semiaxis ellipsoid C 0.25[m] z-semiaxis ellipsoid