"CART is a type of “accommodation” service for people with disabilities. In function, CART is similar to sign language interpreting for people who are deaf, because it transforms spoken language into a visual format that is appropriate for people with hearing loss. But CART can be used by the 95% of hard of hearing and deaf people who do not use American Sign Language (ASL) to communicate."
(Source: http://www.visiblevoices.com/faq.html)