Bimodal language acquisition; Language acquisition (sign language) ; Spracherwerb (Gebärdensprache) ; Sign language (language acquisition) ; Erstspracherwerb; First language acquisition; Ontogenese; Language acquisition ; Spracherwerb und neurologische Entwicklung; Language acquisition and neurological development; Sprache und Denken (Ontogenese) ; Language and thought (ontogenesis) ; Cognitive development; Language acquisition and cognitive development ; Hearing disorders