In order for RadCaptcha to be accessible for visually-impaired users, the control can generate an audio code.
To enable this functionality, you need to set the CaptchaImage-EnableCaptchaAudio property to true. This will cause the link button that retrieves the audio code to be rendered below the CaptchaImage.
To control the visual appearance of the link button, the rcCaptchaAudioLink CSS class should be used.
It is possible to add noise to the audio code functionality by setting the property CaptchaImage-EnableAudioNoise to true.