• Articulation or speech sound disorder occurs when mistakes continue past a certain age. Every sound has a different range of ages when the child should make the sound correctly. Speech sound disorders include problems with articulation (making sounds) and phonological processes (sound patterns).
     
    Phonological process disorder involves patterns of sound errors. For example, substituting all sounds made in the back of the mouth like "k" and "g" for those in the front of the mouth like "t" and "d" (e.g., saying "tup" for "cup" or "das" for "gas").
     
    Childhood Apraxia of Speech (CAS) is a motor speech disorder. Children with CAS have problems saying sounds, syllables, and words. This is not because of muscle weakness or paralysis. The brain has problems planning to move the body parts (e.g., lips, jaw, tongue) needed for speech. The child knows what he or she wants to say, but his/her brain has difficulty coordinating the muscle movements necessary to say those words. 
     
    Dysarthria is a motor speech disorder. It results from impaired movement or weakness of the muscles used for speech production, including the lips, tongue, vocal folds, and/or diaphragm.  
     
    Stuttering affects the fluency of speech. It begins during childhood and, in some cases, lasts throughout life. The disorder is characterized by disruptions in the production of speech sounds, also called "disfluencies." Most people produce brief disfluencies from time to time. For instance, some words are repeated and others are preceded by "um" or "uh." Disfluencies are not necessarily a problem; however, they can impede communication when a person produces too many of them. 
     
    Expressive language disorder: Problems with talking.
     
    Receptive language disorder: Problems with understanding.
     
     
     
    Credit: http://www.asha.org/public/speech/disorders/ChildSandL.htm