Dumbness. There is hardly any condition of the vocal organs compatible with life in which speech is entirely prevented; for when the larynx is so diseased that no voice-sounds are produced there (Aphonia, q.v.), whispering is in general still possible. Even after complete removal of the tongue, tolerably good power of articulation may be recovered. Only when the larynx is completely obstructed, so that no air can pass by the mouth, and breathing is carried on entirely through a tracheotomy tube, is speech rendered impossible.
The usual causes of dumbness are, first and most important, deafness, congenital or occurring in early life; and even this, patient training by the 'oral method' (see DEAF AND DUMB) is able to overcome, showing clearly that it is the want of hearing the sounds to be imitated which leads to the absence of speech in so-called 'deaf-mutes': secondly, morbid conditions of the brain and nervous system, idiocy, hysteria and allied conditions, localised disease of the brain (see APHASIA). Lunatics and malingers sometimes maintain silence for long periods. It occasionally happens that a child, obviously not deaf nor unintelligent, from diffidence or laziness, does not begin to speak till long past the usual age, but persists in expressing his meaning by signs. This condition can usually be remedied by sending him to live for a time among strangers, by whom his signs are not understood.