Help! 508 compliant CAPTCHA

We are looking for a CAPTCHA framework that is section 508 compliant. Tha开发者_如何学Pythont means it must have the audio read out feature for visually disabled people.

Do you know of a CAPTCHA framework other than reCaptcha that is 508 Compliant, apart from reCaptcha ( Google owned)?

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Have you tried http://www.captcha.net/?

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I think this page can be very useful: http://www.evengrounds.com/developers/is-captcha-section-508-compliant