Optical depth of both bound–bound and bound–free self-absorption from simulated hot winds for M81* (left panel) and NGC 7213 (right panel) with an inclination angle of 15°, assuming different turbulent velocities. Vertical magenta dashed lines mark the rest-frame central energy of O VIII Lyα and Ne X Lyα emission lines. Hot wind self-absorption may suppress the intensity of O VIII Lyα in M81* while remaining reasonably negligible for Ne X Lyα and in NGC 7213.