What is the name of the terminal-type device used for communication by the deaf or hearing impaired?

The terminal-type device commonly used for communication by the deaf or hearing impaired is indeed known as a TTY, which stands for Text Telephone or Telecommunications Device for the Deaf. This device allows individuals to communicate over telephone lines by typing messages that are transmitted as text. TTY users can send and receive messages in real-time, which is essential for effective communication in situations where voice calls are not accessible.

TTY devices operate by using a keyboard for input and a display for reading messages. They connect to standard telephone lines, enabling users to communicate with other TTY users or through a relay operator who can convert typed text to spoken words for hearing individuals. This functionality makes TTY an essential tool for inclusion in communication, particularly for those who are deaf or hard of hearing.

By contrast, the other options, while related to communication, do not serve the same direct purpose in aiding deaf or hearing-impaired individuals. For example, video relay devices use sign language interpretation, and voice recognition systems convert spoken words into text, but they are not specifically designed as terminal devices for text communication in the same manner as TTY.