Applies to any technology that has a sound track and visual content.
This technique relates to:
The objective of this technique is to provide an audio (spoken) version of information that is provided visually so that it is possible for people who cannot see to be able to understand audio-visual material better.
Since most user agents today cannot merge multiple sound tracks, this technique adds the additional audio information to synchronized media by replacing the soundtrack with a new copy of the original soundtrack that has the additional audio description added. This added information focuses on actions, characters, scene changes and on-screen text (not captions) that are important to understanding the content.
Since it is not helpful to have this new information obscure key audio information in the original sound track (or be obscured by loud sound effects), the new information is added during pauses in dialog and sound effects. This limits the amount of supplementary information that can be added to program.
The soundtrack with the audio description (of visual information) can either be an alternate sound track that the user can choose, or it can be the standard sound track that everyone hears.
Example 1: A travelogue of the northeast has additional audio description added during the gaps in the dialog to let listeners who are blind know what the person is talking about at any point in time.
Example 2: A lecture has audio description added when the instructor says things like "and this is the one that is most important" to let listeners who are blind know what "this" is.
Example 3: A movie file has two audio tracks, one of which has audio description. Users can choose either one when listening to the movie.
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(none currently listed)
Select audio track with descriptions if there is a choice of audio tracks
Listen to the synchronized media
Check to see if gaps in dialog are used to convey important information regarding visual content
#3 is true