DEAFNESS resulting from genetic causes may be present at time of birth (congenital) or may develop subsequent to birth (acquired). In congenital deafness the end-or-gan of hearing may not develop in the first trimester (aplasia). It is also conceivable, but not proven, that a fully differentiated sense organ may degenerate during the second and third trimester of pregnancy. The aplasias are generally accepted as being congenital and nonprogressive. Genetic deafness may first become apparent during infancy, childhood, or early adult life and thedeafnessmay be considered acquired although the genetic deficiency is obviously not.1 Goodhill2has divided hereditary deafness occurring after birth into infantile and adult types. According to the age of onset of genetic deafness (heredodegenerative) Cawthorne3believed there is a continuous distribution, beginning either in early infancy or throughout childhood, up to the age of 30 years. Heredodegenerative deafness is usually progressive and