Abstract
Since 1990s education for children with hearing impairment in Japan has gradually tried to utilize manual communication. It is now necessary to understand theories of language acquisition, background and practice. After an explanation of definitions of manual communication systems and sign languages, studies related to language acquisition and language background for people with hearing impairment are reviewed in terms of theoretical backgrounds and future directions. Studies in foreign countries on sign language acquisition and early sign language practices indicate that children with hearing impairment can develop language and cognition abilities by communicating with others from early childhood. It is expected that teachers in schools for the deaf, researchers, parents of children with hearing impairment, and deaf adults in Japan will examine the environment in which children are raised and educated, and improve that environment in the future.
