Dumbness is the inability to pronounce the sounds that make up words. DEAFNESS is the most important cause, being due to a congenital brain defect, or acquired brain disease, such as tertiary SYPHILIS. When hearing is normal or only mildly impaired, dumbness may be due to a structural defect such as tongue-tie or enlarged tonsils and adenoids, or to ine?cient voice control, resulting in lisping or lalling. Increased tension is a common cause of STAMMERING; speech disorders may occasionally be of psychological origin.
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; and throat cancer may require a LARYNGECTOMY, with subsequent help in communication. Severe psychiatric disturbance may be accompanied by impaired social and communication skills. (See also VOICE AND SPEECH.)
Treatment The underlying cause of the problem should be diagnosed as early as possible; psychological and other specialist investigations should be carried out as required, and any physical defect should be repaired. People who are deaf and unable to speak should start training in lip-reading as soon as possible, and special educational methods aimed at acquiring a modulated voice should similarly be started in early childhood – provided by the local authority, and continued as required. Various types of speech therapy or PSYCHOTHERAPY may be appropriate, alone or in conjunction with other treatments, and often the ?nal result may be highly satisfying, with a good command of language and speech being obtained.
Help and advice may be obtained from AFASIC (Unlocking Speech and Language).... speech disorders
Voice This has three varying characteristics: loudness, pitch, and quality or timbre. Loudness depends on the volume of air available and therefore on the size of the chest and the strength of its muscles. Pitch is determined by larynx size, the degree of tenseness at which the vocal cords are maintained, and whether the cords vibrate as a whole or merely at their edges.
In any given voice, the range of pitch seldom exceeds two and a half octaves. Typically, the small larynx of childhood produces a shrill or treble voice; the rapid growth of the larynx around PUBERTY causes the voice to ‘break’ in boys. Changes in the voice also occur at other ages as a result of the secondary action of the SEX HORMONES. Generally speaking, the adult voice is bass and tenor in men, contralto or soprano in women. Timbre is due to di?erences in the larynx, as well as to voluntary changes in the shape of the mouth.
Speech Rapid modi?cations of the voice, produced by movements of the PALATE, tongue and lips. Infants hear the sounds made by others and mimic them; hence the speech centres in the BRAIN are closely connected with those of hearing.
Defects of speech See below, and also SPEECH DISORDERS. MUTISM, or absence of the power to speak, may be due to various causes. LEARNING DISABILITY that prevents the child from mimicking the actions of others is most common; in other cases the child has normal intelligence but some neurological disorder, or disorder of the speech organs, is responsible. Alternatively, complete DEAFNESS or early childhood ear disease may be the cause. STAMMERING is a highly individual condition, but is basically a lack of coordination between the di?erent parts of the speech mechanism. (See also main entry on STAMMERING.) DYSPHASIA is the inability to speak or understand speech, most commonly following brain disease, such as STROKE. APHONIA or loss of voice may be caused by LARYNGITIS or, rarely, a symptom of conversion and dissociative mental disorders – traditionally referred to as HYSTERIA. It is generally of short duration.... voice and speech
Air is trapped in the oesophagus and is gradually expelled while the tongue, palate, and lips form distinguishable sounds.... oesophageal speech