Rytov's method has been the subject of arguments as to whether or not it has a greater domain of applicability than the method of small perturbations. In order to be able to use the result of Rytov's method one must assume that the sizes of the patches of inhomogeneity are much larger than the wavelength of the sound, i.e., λ≪l. Making use of this assumption, when we use the solution for Ψ′ to compare the discarded term |▿Ψ′|2with the remaining terms, we discover that Rytov's method has thesamedomain of applicability as the method of small perturbations. Using a simple geometrical model we deduce by physical reasoning the results of Mintzer and Bergmann. This model is then used to extend the theoretical prediction for the amplitude fluctuations in the (Mintzer) range(λL)12≫L0to cover the case where the fluctuations are large.