Because using a screen reader on our pages can be very time consuming, we don't want to add extra text unless it is necessary. In general any visually hidden text that we add should be conveying information that a signed user is getting visually. An example of this is when content is visually associated with each other and we want to make that connection for the screen reader.
A screen reader user will understand the same text and abbreviations that a sighted user does so text should not be added to extend these. Most screen readers also have settings that allow the user to determine how abbreviations read and we don't want to override that by changing the text for them.
- Visually hidden text conveys information that a sighted user is getting in another way.
- Visually hidden text is not added for visual abbreviations.