Exponential damping times for the different initial amplitudes, (A), and inhomogeneous layer widths, represented by diamond (⋄), triangle (△), square (□), and pentagon (), in increasing order. The stars (⋆) of the same colour as the symbols, represent the theoretically predicted damping time for the specific layer width and sinusoidal layer density profile. Analogously, the asterisks (E) represent the predicted damping for a linear layer density profile (Goossens et al. 2002).