When did American Sign Language develop?
American Sign Language
ASL emerged as a language in the American School for the Deaf (ASD), founded in 1817. This school brought together Old French Sign Language, various village sign languages, and home sign systems; ASL was created in this situation of language contact. ASL was influenced by its forerunners but distinct from all of them.
American Sign Language phonology
Sign languages such as American Sign Language (ASL) are characterized by phonological processes analogous to, yet dissimilar from those of oral languages. Although there is a qualitative difference from oral languages in that sign-language phonemes are not based on sound, and are spatial in addition to being temporal, they fulfill the same role as phonemes in oral languages.