kx_e sin(theta0) Plane wave direction, x
ky_e -cos(theta0) Plane wave direction, y
k0 intop2(acpr.k) Free-field wave number
kx k0*kx_e Background plane wave k_x
ky k0*ky_e Background plane wave k_y
p_inc acpr.p_b Incident plane wave (background pressure field)
p_scat acpr.p_s Scattered wave (air domain)
Z aveop1(acpr.p_t/(nx*down(acpr.vx)+ny*down(acpr.vy)))/intop2(acpr.rho*acpr.c) Specific surface normal impedance
R aveop1(down(p_scat/p_inc)) Reflection coefficient (averaged)
alpha_R 1-abs(R)^2 Absorption coefficient (based on R)
Pin intop3(-acpr.I_by) Incident power
Pout intop3(acpr.I_sy) Outgoing power
alpha 1-Pout/Pin Absorption coefficient