What are speech disorders?

Speech disorders are variations permitted under the "standard language". Assessing whether a deviation from standard language exists can be done according to certain criteria: the age disparity between the subject and his speech, the stationary character of the disorders, the susceptibility to generate neuropsychological complications and the need for speech therapy treatment.
The number and diversity of language disorders has made the classification difficult.
Generally different criteria are used: the linguistic criterion, the etiological criterion, the morphological and symptomatically one.