  Acoustic wave fields propagating long ranges through the ocean are refracted
by the inhomogeneities in the ocean's sound speed profile. Intuitively, for a
given acoustic source frequency, the inhomogeneities become ineffective at
refracting the field beyond a certain fine scale determined by the acoustic
wavelength. On the other hand, ray methods are sensitive to infinitely fine
features. Thus, it is possible to complicate arbitrarily the ray dynamics, and
yet have the wave field propagate unchanged. This feature raises doubts about
the ray/wave correspondence. Given the importance of various analyses relying
on ray methods, a proper model should, at a minimum, exclude all of the fine
structure that does not significantly alter the propagated wave field when the
correspondence to the ray dynamics is integral. We develop a simple, efficient,
smoothing technique to be applied to the inhomogeneities - a low pass filtering
performed in the spatial domain - and give a characterization of its necessary
extent as a function of acoustic source frequency. We indicate how the
smoothing improves the ray/wave correspondence, and show that the so-called
``ray chaos'' problem remains above a very low frequency (about 15-25 Hz).
