Preconditions of language development in deaf children.

The harmful effects of childhood hearing impairment are given little thought by many people because hearing loss is largely an invisible handicap. An infant with a hearing impairment is generally healthy-looking and develops relatively normally during the first year of life. Hearing impairment in infants interferes with the normal development of spoken language. We are biologically programmed to develop certain skills in response to certain inputs. Language learning is one such skill which must be gained very early in life. Hearing is the most important basis for normal language acquisition and language is the keystone of modern society. Hearing loss must be identified as early as possible in the first years of life, especially a child with profound or severe hearing loss must be identified in the first year of life. If not, the child has missed an irreversible sensitive phase for learning of speech and language.