  The energy dependence of $90^o$ $cm$ fixed angle scattering of $\pi p \to
\pi' p'$ and $\gamma p\to \pi^+ n$ at large momentum transfer are found to be
well described in terms of interfering short and long distance amplitudes with
dynamical phases induced by Sudakov effects. We calculate the color
transparency ratio for the corresponding processes in nuclear environments $\pi
A\to \pi'p(A-1)$ and $\gamma A\to \pi N (A-1)$ taking nuclear filtering into
account. A prediction that the transparency ratio for these reactions will
oscillate with energy provides an important test of the Sudakov phase shift and
nuclear filtering hypothesis which is testable in upcoming experiments.
