Deafness as a Culture
Deafness is more than a medical condition. Many consider it a way of life. Individuals who are deaf, especially those with life-long deafness, often belong to a community—a culture. This if often referred to as the Deaf (with a capital "D") community with its participants often identifying as being "Deaf" (with a capital "D"). Because most Deaf people tend to communicate in sign language as their primary and shared language, English is a second language, and understanding complicated messages in English can be difficult.
There is a distinct sense of pride among the Deaf, and they enjoy the status of a cultural and linguistic minority. In recent decades, sign language has played an increasingly central role in the cultural unification of the Deaf community.
Sign Languages and "Lip Reading"
There are, however, deaf people who do not use sign language. These people have generally been raised in the oral tradition, meaning that they were taught to speak vocally, and to "read the lips" of others. This tradition was more common throughout most of the 20th century. It wasn't until the 1970s that educators began to seriously question this approach, and to encourage the use of sign language as a primary means of communication. Sign language itself was not even recognized as a language by many people in the field, and many thought it lacked the functionality of a true language. Today we understand that sign language has a complete syntax and grammar structure, and that it activates the same neural pathways and brain activities as all other languages.
Controversy exists between the proponents of the oral tradition and the proponents of sign language immersion. Proponents of the oral tradition seek to encourage deaf individuals to be a part of mainstream society. The assumption is that deaf people will be more acceptable and accessible to people who are not deaf if the deaf can carry on "normal" conversations with them. The biggest downside to this approach is that lip-reading is an inexact art of intuition and guesswork. Lip-readers are able to reliably understand about 40-60% of what others say and must fill in the blanks for the rest of the conversation—even after years of training and practice.
Sign language versions of multimedia
One may think it best for web accessibility to provide a sign language version of audio content, but not all deaf people understand sign language and there are over 130 different sign languages world-wide.
In the United States, for example, the most common sign language is American Sign Language, or ASL. In Britain, British Sign Language, or BSL, is the most common. In Australia, Australian Sign Language, or Auslan, is the most common. Signed English is another variation, although it is less of a full-featured language and more of a translation of spoken English into a system of signs.
When you branch out to Europe, South America, and Asia, the differences are even more pronounced. Asian sign languages have almost nothing in common with American or European sign languages, and have no common linguistic root. Despite attempts to create and adopt an international sign language known as Gestuno, there is not one kind of sign language that is universally understood.
The fact that there are many different sign languages around the world is not really a matter of disability access so much as it is a matter of internationalization. The common thread between those who speak ASL, BSL, and Auslan is not sign language, it is English—even after considering the regional differences of spelling and usage.
To support optimal accessibility, web multimedia should provide captions and transcripts. When the demographics of the target audience support it, consider a relevant sign language alternative.