captchas for blind?

[der.hans]

moin moin,

do people with vision problems just get locked out of sites using
captchas?

Are there braille interpretations for captchas?

Are there audio captchas? If there are, what if the person is vision
impaired and can't hear the audio file ( I believe audio still isn't part
of HTML specifications, browser and/or computer might not support sound,
person might also be hearing impoaried, etc. )?

ciao,

der.hans
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