  We exhibit a situation in which cosmological perturbations of astrophysical
relevance propagating through a bounce are affected in a scale-dependent way.
Involving only the evolution of a scalar field in a closed universe described
by general relativity, the model is consistent with causality. Such a specific
counter-example leads to the conclusion that imposing causality is not
sufficient to determine the spectrum of perturbations after a bounce provided
it is known before. We discuss consequences of this result for string motivated
scenarios.
