By age three, a child should be understood by members of the family. By age five, he or she should have achieved clear production of almost all sounds. Children with pronunciation difficulties may have some weakness of the jaw, lips, and tongue (dysarthria). They may have difficulty understanding and organizing the sound system of English, making many unusual errors (phonological disorder). They may also have motor coordination difficulties (apraxia). Speech difficulties may be related to one or any combination of the above types. Treatment is individualized according to each child's profile. Even teenagers and adults with long-standing pronunciation problems can attain clear speech with therapy.