Forced subtitles appear by default and are "closed" (users can't turn them off). They serve a range of purposes:
Translate "foreign" language audio as the primary language of the program
Translate small amounts of "foreign" language audio, which the content creator wants the viewer to understand
Clarify moments of muffled speech in the same language as the audio
Other text not directly corresponding to audio, such as: crawls, chapter titles, credits
User needs and use cases:
I see and understand most visual content in video, but have difficulty reading visible text. (Children; people with low literacy in a particular written language; people with dyslexia). As a user I want to hear a spoken version of the forced subtitles, in the same spoken language as the writing, but not hear audio description of other visual content.
I use audio description for nonvisual access to most visual content, but I understand the "foreign" language of certain forced subtitles so I don't need audio description of those. I want to hear the original audio of these language bits, not a dubbed translation equivalent of the forced subtitles.
I want the option of hearing other text (such as crawls and credits), but I want to control the verbosity.
Forced subtitles appear by default and are "closed" (users can't turn them off). They serve a range of purposes:
User needs and use cases: