[2] The delays and disorders can range from simple sound substitution to the inability to understand or use one's native language.

[3] This article covers subjects such as diagnosis, the DSM-IV, the DSM-V, and examples like sensory impairments, aphasia, learning disabilities, and speech disorders.

For example, the definitions offered by the American Speech–Language–Hearing Association differ from those of the Diagnostic Statistical Manual 4th edition (DSM-IV).

[3] In general, communication disorders commonly refer to problems in speech (comprehension and/or expression) that significantly interfere with an individual's achievement and/or quality of life.

Diagnosis involved testing and evaluation during which it is determined if the scores/performance are "substantially below" developmental expectations and if they "significantly" interfere with academic achievement, social interactions, and daily living.