Deaf and Dumb is the term commonly used to describe persons who, through deafness, are unable to hear the spoken words of others, and who, consequently, remain dumb. Deafness is the cause, dumbness the consequence. Thus the term "deaf and dumb" is a misnomer, for the deficiency is single, not two-fold, although in the result it affects the two organs of hearing and speech.
Deafness is either congenital or acquired. Congenital deafness arises from some natural cause, which deprives the child of hearing from its birth. Acquired deafness arises from disease, accident, or other causes.