Hello,
Thanks for this feedback. As you can imagine, testing accessibility is difficult. We're hoping that we can get it right once, and then provide an accessible CAPTCHA for everybody. I really appreciate you sharing your technical expertise in this matter.
the image that enables one to play the audio alternative
lacks alt text, which is a REQUIRED attribute for an image
declaration in HTML4x/XHTML1;
[ http://www.w3.org/TR/html401/struct/objects.html#h-13.2]
[http://www.w3.org/TR/html401/struct/objects.html#alternate-text]
[ http://www.w3.org/TR/html401/appendix/notes.html#accessibility]
[http://www.w3.org/WAI/References/HTML4-access]
the list of graphical elements reveals that there are actually
3 button-type objects that are part of the form, and essential
to anyone who actually needs the audio alternative:
red/reset
red/audio
red/help
MUST be ALT-texted as follows:
<img src="red/reset" alt="Reset"
<img src="red/audio" alt="Audio Alternative"
<img src="red/help" alt="Help
the image that serves as the hyperlink to the audio alternative is
not a form control; it should be a BUTTON, so it is in the form's
TABINDEX order, not outside of the form as a javascripted link;
[http://www.w3.org/TR/html401/interact/forms.html#edef-BUTTON ]
using the type="button" push-button mechanism to which to attach
the script that calls the audio alternative.
<button type="button" name="audio-alt" accesskey="r"
title="Alternative Audio CAPTCHA Key"></button>
i would STRONGLY suggest that an ACCESSKEY be associated with
the audio alternative - perhaps 'r' for read (it won't steal most
browsers' menu hotkeys)
[http://www.w3.org/TR/html401/interact/forms.html#h-17.11.2]
[ http://www.w3.org/TR/WCAG10-HTML-TECHS/#link-accesskey]
[http://www.w3.org/TR/WCAG10-HTML-TECHS/#forms-keyboard-access]
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ISSUE 3
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the audio alternative doesn't play if you don't have QuickTime
installed, and most people who will benefit from an audio alternative
will NOT have QuickTime installed, as it is infamous for not playing
well with assisstive technologies;
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ISSUE 4
=======
if one is patient (and lucky) enough to find and activate the
quote Can't hear this sound? unquote link, the audio clip doesn't
play using the user agent's default backplane audio rendering engine
(the thing that plays embedded sounds), but, instead, opens whatever
media player one has associated with the filetype being served
client-side; this means that one must manually switch between
applications in order to type as text the contents of the audio
alternative -- a feat complicated by the choice of backwards looping
voices and other background sounds -- into the pertinent field; of
course, every INPUT defined for the FORM should use the LABEL element;
[http://www.w3.org/TR/html401/interact/forms.html#h-17.9 ]
i very strongly recommend that the FORM (to whose document source
i cannot get, so i can't make corrections and inline comments) be
placed in a FIELDSET with a LEGEND - consult:
[http://www.w3.org/TR/html401/interact/forms.html#h-17.10 ]
[http://www.w3.org/TR/WCAG10-HTML-TECHS/#forms-grouping]
nor can i overstress the importance of the LABEL element in
contextualizing FORM controls:
[http://www.w3.org/TR/html401/interact/forms.html#h-17.9]
[http://www.w3.org/TR/WCAG10-HTML-TECHS/#forms-labels ]
TABINDEX (determines order through which controls are TAB navigated,
which is VERY helpful when visually one wants the submit control
immediately after the text-entry field, but for which there are
modifiers, assistance mechanisms, or alternatives), which should
be TABINDEX-ed in a logical sequence ENDING with the Submit button:
[http://www.w3.org/TR/html401/interact/forms.html#h-17.11.1 ]
[http://www.w3.org/TR/WCAG10-HTML-TECHS/#forms]
i wish i could have been of more specific assistance to you, but
i could not obtain the actual document source for the reCAPTCHA
form; from what i could obtain of the document source, i would
be wary of including this information in an IFRAME, unless that
is part of the security protocol you are using.
here are the main accessibility resources cited above, and which
should be implemented in as important a gate-keeper as a CAPTCHA
at Level Triple A compliance to the Web Content Accessibility
Guidelines:
[http://www.w3.org/TR/WCAG10/#Conformance]