Age of onset refers to the age when the deafness occurred.
Generally, age of onset is separated into five categories:
- birth or early life (before three to four years of age), which is called pre-lingual deafness,
- childhood (usually between the ages of five and 12),
- adolescence or pre-vocational (usually between the ages of 13 and 20),
- post-vocational (usually between the ages of 21 and 44),
- age-related deafness (from 45 onwards),
Essentially, the earlier that the deafness occurs – particularly if the degree of deafness is severe to profound – the greater the impact on both language and learning. This is not surprising if you think about the learning milestones that occur during infancy and childhood and how deafness creates barriers to accessing information.
Those barriers to information also exist for those who acquire deafness later than childhood; however, as language has already been developed, the impact of the barriers relate more to communication access and less so to language and learning development.
It is uncommon for people who acquire deafness from late-childhood onwards to learn Auslan. This does not mean that accessing information is an easy task; however, it does mean that the use of English – assuming they are Australian born –as their primary language is well-established.