A short review of influence of ionic mobility on acoustic properties of crystals is presented. Different kinds of ionic mobility in solids are discussed: acceleration of self-diffusion in insulators at high temperature, mobility of ions in superionic crystals, mobile impurities and vacancies. High ionic mobility leads to pronounced acousto-ionic interaction, which has specific temperature and frequency dependences. The main attention is focused on alterations in sound velocity and attenuation due to acousto-ionic interaction in superionic, doped and imperfect crystals possessed high ionic localized and delocalized mobility already at moderate temperatures.