Most of us have not heard of machine translation for sign language, but it’s an exciting technological development that helps people who are deaf or hard of hearing communicate with the hearing world, most of which does not know sign language. Machine translation systems for sign-language can do this by automatically converting signs into text or spoken dialogue, then back into sign language, without needing a human interpreter.

Machine translation for sign language has been around since the 1970s, but it has been difficult for developers to perfect the technology because sign language constructs differ greatly from those of spoken languages.

Here are a few machine translation inventions from the past and some more recent developments on the market.