One switch at the side of Kris' head controls the dot signal, while another produces the dash signal. This fascinating device, as well as many others, uses special hardware implementations to allow the device to work. Special electrodes can pick up the small electrical signals created by the slightest movement in a muscle. These electrodes are able to detect the electrical currents generated by the moving of the muscle. The electrode connects to another device, which operates a switch that controls inputs into the computer.
Some deaf people can hear sounds, such as a bell ringing or a door slamming.
A deaf person can learn to communicate in many ways. They can learn through sight what the ear cannot hear. Lip-reading, American Sign Language, reading, and writing all help them learn, to name a few. Therefore deaf or hearing-impaired people can utilize the same programs that everyone else uses. There are, of course, special hardware and software items available for specific cases.