These may be of physical or psychological origin – or a combination of both. Difficulties may arise at various stages of development: due to problems during pregnancy; at birth; through childhood illnesses; or as a result of delayed development. Congenital defects such as CLEFT PALATE or lip may impair speech until surgery is performed, and recurrent ear infections may make hearing difficult so the child's experience of speech is limited. Childhood DYSPHASIA occurs if the language-development area of the BRAIN develops abnormally.
Articulatory problems mean an inability to pronounce properly the sounds that make up words. DEAFNESS is the most important cause. When hearing is normal or only mildly impaired, difficulty in speech may be due to inefficient voice control, resulting in lisping or lalling (a form of stammering in which the speech is almost unintelligible). Increased anxiety is a common cause of STAMMERING.
Normal speech may be lost in adulthood as a result of a STROKE or head injury. Excessive use of the voice may be an occupational hazard, for example in singers. Severe psychiatric disturbance may be accompanied by refusal to speak. (See also VOICE AND SPEECH.)
This depends on the underlying cause. Speech and language therapy assessment and, if necessary any medical, surgical or psychological investigations should be carried out as required. People who are hearing impaired and find speech difficult need training in lip-reading and/or signing as soon as possible, and special educational methods aimed at acquiring a modulated voice should similarly be started in early childhood. The final result may be highly satisfying, with a good command of language and speech being obtained.