We report Brillouin Spectroscopy experiments conducted on ethanol in the liquid and glass states, as well as in the stable crystal, plastic crystal and orientationally-disordered crystal crystal") phases. Both the canonical Supercooled liquid <-> glass transition and the dynamical plastic crystal ( glassy crystal transition are observed as a kink in the Sound velocity at 96K. We have also studied the influence Of small amounts of water on the crystallization kinetics for the stable and the plastic crystal phases, which are slowed down in favour of glass formation even with less than 0.5%, Water impurity.