Raman-scattering measurements have been performed on c-Si and a-Si over a wide range of frequencies, including Stokes and anti-Stokes sides, and up to fourth order. All the features are accounted for by using the same physical parameters in both phases. In particular, it is shown that multiple-order scattering processes are not negligible, but rather of the same order of magnitude as first-order processes. In amorphous materials, light-scattering excess, spurious background, Boson-peak or hot-luminescence processes, which have been recently put forward, turn out to be mainly caused by high-order Raman-scattering processes.