Making CAPTCHA accessible to people with disabilities. What approaches have you used?

I'm nearing the completion of migrating our existing website to a CMS and I've just finished creating all the various contact forms. The CMS I'm using has CAPTCHA built into it's form builder, which is great, but the only method available is the "decipher-the-noisy-image" method.

This approach works well, but it limits access for people who might have reading or sight disabilities. I've worked around this by having a "help" page which allows those with disabilit开发者_JAVA百科ies to contact us by telephone and I'm considering having a single-field form which says "Send us your email address and we'll contact you". Accessibility is of particular importance to me as a web developer, but from an organisational perspective; so is reducing the amount of form spam we receive.

So what I'd like to know is, has anyone in the community had any experience with other CAPTCHA methods and how have you managed to make them accessible to people with disabilities?

---

As a blind person I find that recaptcha is one of the better CAPTCHA services out there as far as an audio option. The issue with using sms as the only alternative is the fact that many visually impaired users don't have cell phones that allow them to read text messages.

---

A good captcha, like reCAPTCHA, usually includes an audio CAPTCHA. Also I have seen a site that will send a SMS message and you enter the code in the sms (Google-gmail will do this).

I am very interested in this because I am implementing a CAPTCHA in jQuery right now.

---

Many sites, including this one I believe, have an option to play noisy audio with embedded spoken numbers, as an audio equivalent to the traditional CAPTCHA image.

I find the result pretty spooky, actually. Reminds me of numbers stations.

---

As Michael said, audio with each character of the CAPTCHA text spoken for better or worse is a common option provided. If your CMS is PHP-based or if PHP is available on the hosting infrastructure you are using anyway, here's an open source CAPTCHA application with an audio download option:

http://www.phpcaptcha.org/

I've implemented a production site with phpcaptcha, and it works as advertised.