Numerical SPL attenuation relative to a reference receiver according to the propagation distance r (blue line), compared to the analytical solution (orange dashed line) for three source-receiver angles: (a) θ = 4°, (b) θ = 10° and (c) θ = 15°. Source located at h_s = 2m and emitting a windowed sinusoidal signal at fmax = 500 Hz (N_ppw = 10). On the error maps on the left, red lines indicate the receiver lines corresponding to the SPL attenuation graphs on the right.