Comparison of Monte Carlo simulation of driven sine functions (blue line) with the full integral (light orange) and the approximations in Eq. (19) (green). All functions have been normalised to the starting value of one. The expected Gaussian damping envelope (Eq. (26)) is shown in red. The time was arbitrarily chosen to be t = 0, and the mean sound speed 152 km s⁻¹ and spread in sound speed σ_v = 26.4 km s⁻¹ were chosen as before.