Naturally, the expression for oblique incidence is more complicated.
Acoustic stealth design on the underwater sandwich composite shell structure in oblique incidence
Acoustic stealth design of underwater sandwich composite added structure under oblique incidence
Sound transmission in a multilayer homogeneous composite plate subjected to oblique incidence plane waves
If you change the view Angle, the partial photonic band gap will shift to short wavelengths for oblique incidence.
Time delay estimation of the shortest path in real-time monitoring of water depth with oblique incidence sonar
