After the age of two the basic process continues to be refined, and many more sounds and words are produced. The procedure is the same in any area of language learning, whether the child is acquiring syntax, phonology or semantics. Throughout the acquisition process a child continually revises and refines the rules of his or her internalized grammar, learning increasingly detailed sub-rules until a set of rules enables a child to create the full array of complex adult sentences. By the age of six or seven the child has all the necessary information about the language system it is immersed in, and can function freely in that system. The process of refinement continues until the age of ten and sometimes longer.
Many linguists believe the child's brain is preprogrammed for language learning.
Whether this is true or not, a child who does not hear language, does not learn one. To understand this concept one must realize that to be preprogrammed for accepting the parameters of a language system only speaks to part of the ability to comprehend and to use a system fluently. Competence comes from this preprogrammed ability and performance comes from practicing within a speech community and refining from the onset of speaking and through a person's lifetime. Children do not acquire language from hearing it spoken by listening to television or the radio. They must interact with real people in the same language to acquire it.