There are some villages in the world where everyone speaks a language in visual-manual modality. In these villages, deafness is not a barrier nor an issue as everyone speaks the same language and the same modality. One of these is a remote Bedouin tribe in southern Israel where everyone uses Al-Sayyid Bedouin Sign Language (ABSL).
In this isolated Al-Sayyid Bedouin community, there is a high incidence of hereditary deafness. As a result of this, indigenous sign language naturally sprang up and evolved. There are over 100 deaf members of the 3,500 villagers in this tribe. Researchers and scientists took the recent opportunity to study the emergence of this language and community..
Fox, Margalit. Talking Hands. "In a remote village where everyone speaks sign language, scientists are discovering the essential ingredients of all human language -- and uncovering the workings of the human mind.
"Al-Sayyid Bedouin Sign Language." University of Haifa. http://sandlersignlab.haifa.ac.il/html/html_eng/al_sayyid.html
Also see: Al-Sayyid Bedouin Community.
Martha's Vineyard Island where everyone on the island used sign language.