Brillouin spectroscopy of acoustic phonons in transparent crystals and nontransparent metallic Co/Cu superlattices is reviewed. The method presents a directional sensitivity of the experiment. This feature is useful in elastic constants measurements in crystals and analysis of in-plane anisotropies of hyper-sound and spin waves in superlattices. Results for the LiTaO3, LiNbO3, LiNbO3:Cu, SLGO, SLAO crystals are provided. Spin wave results for the Co/Cu superlattices are presented.