DEAFNESS

An imperfection of the sense of hearing, arising from a variety of causes, some of which are inexplicable and incurable, and others ascertainable and susceptible of relief or entire removal. When the organ of hearing is imperfect in its functions, either at birth or in childhood, dumbne or imperfect articulation attends it; for speech is an imitative faculty, and an infant born deaf, cannot attempt those motions of the organs of voice which gradually attain perfection by practice: he consequently becomes incapable of communicating his ideas through that medium. Tiie external ear, though tending by its form and situation to improve and perfect the sense of hearing, is in no way nece ary; for it may be cut off without producing deafne . A common cause of deafne arises out of imperfections or obstructions in the pa age leading from the external ear down to the membrane of the tympanum. This pa age is partly cartilaginous and partly bony; and from its oblique direction it is difficult so to see into it as to'ascertain the seat or cause of the obstruction. In some persons, however, when placed in a proper position, so that the sunshine or other strong light may be properly directed into it, a little management enables us to examine nearly its whole extent. In some cases of congenital deafne this pa age is closed by a membrane, which, if near the external orifice, is easily detected, and may be divided or removed; but, if deeply seated,»it may escape observation till the child attains a certain age, or should begin to talk: for till that time the deafne of infants often pa es unobserved. Under these circumstances, and where the malformation exists m both ears, [s. 328]