By Adjunct Associate Research Professor Kate Crowe (pictured, inset) in the speech pathology discipline in the Charles Sturt School of Allied Health, Exercise and Sports Sciences.

The 23rd of September is annually recognised as the International Day of Sign Language. It is a day when we celebrate the diversity and rich history of sign languages and support and protect the linguistic and cultural identities and diversity of all sign language users.

Did you know that there are approximately 300 sign languages in the world?

Many people assume that there is only one sign language, and express disbelief when told otherwise.

“Why? Wouldn’t it be more sensible if there was just one signed language? Then Deaf people could communicate with each other?” (I note that ‘Deaf’ with a capital ‘D’ is used to refer to a person with lived experience of hearing loss who identifies as being culturally deaf and a member of the Deaf community.)

Undoubtedly, this is true, but could the same not be said for spoken languages?

So why is there such a rich diversity in sign languages? The answer is, for the same reason that there is in spoken languages.

Sign languages emerge from a community of people with a need to communicate with each other.

As different sign languages were born, there was very little contact between the communities who used each language.

How and why would Deaf people in Australia and in Ghana be in contact for a common sign language to evolve?

For this reason, sign languages, just like spoken languages, are parts of different families which describes the relative distance between languages. And the families are not what you would expect.

Auslan (Australian Sign Language) is a member of the BANZSL family (British, Australian and New Zealand Sign Language). Sign languages in this family all evolved from Old British Sign Language and retain some level of mutual intelligibility today.

Along with Auslan, members of this family include British, Maritime, New Zealand, Northern Ireland, Papua New Guinea, and South African Sign Languages.

Sign languages evolve independently to the spoken language they co-exist with.

People are often surprised that Auslan and American Sign Language (ASL) have very little in common, not even having the same alphabet.

This is because while Auslan belongs to the BANZSL family, ASL belongs to the Francosign family which originates from Old French Sign Language.

The Francosign family includes ASL and Dutch, French, Flemish, French-Belgian, and Italian Sign Language.

There is also an international sign language. This is a ‘language’ used by Deaf people to facilitate cross-linguistic communication in settings such as in international conferences and meetings.

However, it is not a natural or complete signed language, like Auslan. It is considered a pidgin form of sign language as it has been created, lacks the complexity of natural sign languages, and has a limited lexicon.

According to the World Federation of the Deaf and the World Health Organization, more than 70 million people worldwide live with hearing loss. More than 80 per cent of these people live in developing countries. Many of these people are users of sign languages and identify as Deaf.

Awareness and recognition of sign languages is important for the full realisation of the human rights of people who are Deaf.

The United Nations’ resolution for this day also states that early access to sign language and the provision of quality education and services in sign language is critical to the achievement of the Sustainable Development Goals of the United Nations.

As part of the International Decade of Indigenous Languages, it is especially important to recognise the importance of Indigenous sign languages.

In Australia, there are multiple Indigenous sign languages that have been preserved, revitalised, and/or created. These include Takataka (Gurindji Sign Language) and Yolŋu (Yolngu) Sign Language. More information on Indigenous Sign Languages can be found here.