A system of sounds by which humans communicate. Children learn speech through listening to and imitating the speech of others.Speech production originates in 2 regions of the cerebral cortex on each side of the brain. These regions are linked to the centre for language expression (Broca’s area) in the dominant hemisphere. They send signals down nerve pathways to muscles controlling the larynx, tongue, and other parts involved in speech. The cerebellum plays a part in coordinating movements of these parts. Air from the lungs is vibrated through the vocal cords in the larynx. This produces a noise, which is amplified in the cavities of the throat, nose, and sinuses. The sound of the vibrated air is modified by movements of the tongue, mouth, and lips to produce speech sounds.
Terms applied to the sounds produced in the upper AIR PASSAGES which form one of the means of communication between human beings. Air passes through the LARYNX to produce the fundamental notes and tones known as voice. This is then modi?ed during its passage through the mouth so as to form speech or song.
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
the treatment of patients who have problems with communication or eating or drinking because of congenital causes, accidents, or illness (e.g. stroke). Speech and language therapists are *allied health professionals who have special training in this field.... speech and language therapy
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