The paper identifies and defines augmentative and alternative communication, a new sub-discipline in applied linguistics whose primary parametre is linguistic competence whereas the secondary parameter is the phenomenon of speech inability and speech non-occurrence. At the same time it has been proven that linguistics of augmentative and alternative communication conducts primary, applied and implementation research having a hierarchical layout of scientific aims. It also enables to conduct a logopaedic analysis of mute and non-speaking persons. The postulates that govern it are presented in the last part of the text.