A time-dependent presentation is a presentation which
Media equivalents present essential audio information visually (captions) and essential video information auditorily (audio descriptions).
People who are deaf or have a hearing loss can access the auditory information through the captions. People who are blind or have low vision as well as those with cognitive disabilities who have difficulty interpreting visually what is happening benefit from the audio descriptions of the visual information.
People without disabilities also benefit from the media equivalents. People in noisy environments or with muted sound often use captions. Captions are used by many to develop language and reading skills. Audio descriptions also provide visual information for people who are temporarily looking away from the video presentation such as when following an instructional video and looking at their hands. Captions and text descriptions can also be used to index and search media files.
Note:Time-dependent presentations that require dual, simultaneous attention with a single sense can present significant barriers to some users. Depending on the nature of the of presentation, it may be possible to avoid scenarios where, for example, a deaf user would be required to watch an action on the screen and read the captions at the same time. However, this would not be achievable for live broadcasts (ex. a football game). Where possible, provide content so that it does not require dual, simultaneous attention or so that it gives the user the ability to effectively control/pause different media signals.