The majority of the estimated 20,000 adults in the US who are deaf and blind have Usher's Syndrome, a disease characterized by deafness at birth and a gradual loss of sight in young adulthood. As their sight diminishes they resist learning braille, which is difficult to master as an adult and is an admission of a dual sensory loss. For this reason, augmentative communication devices employing braille may be inappropriate for people who are deaf and blind. Instead of visually recognizing the gestures as deaf people do, deaf-blind individuals feel and interpret the motion and positions of the hand as the message is spelled out, one letter at a time by the interpreter. The communication partners must be in physical proximity with each other.
Professional interpreters are difficult to locate and schedule.
The presence of interpreter may intrude on the privacy of a conversation. Extreme informational and social isolation can occur without communication. An electromechanical hand provides a deaf-blind person some independence in communication. These movements are felt by a deaf-blind user and interpreted as the fingerspelling equivalents of the letters comprising a message. With a fingerspelling hand, a deaf-blind individual need not rely on a human interpreter for all communication.