speech defect, any condition that interferes with the mental formation of words or their physical production. Speech defects in children generally become apparent in the early school years. Speech problems may arise from organic or functional abnormalities, but in practice the two are often hard to differentiate. Organic defects include deafness, cleft palate, dental abnormalities, and brain damage; most functional problems are basically psychological. Speech defects are generally categorized as disorders of sound production; disorders of voicing, e.g., loudness, pitch, and quality deviations; disorders of rhythm, such as stuttering and stammering; and disorders of language formulation and expression, including aphasia, the inability to use words as symbols of ideas. Treatment of a speech defect may include correction of organic conditions, psychotherapy, and training in proper articulation; it is rarely limited to a single type of therapy.