Classification Congenital deafness Hereditary deafness a Non hereditary deafness Acquired deafness Prelingual deafness Postlingual deafnessClassification ◼ Congenital deafness ◼ Hereditary deafness ◼ Non hereditary deafness ◼ Acquired deafness ◼ Prelingual deafness ◼ Postlingual deafness