A telecommunications device for the deaf (TDD) is a teleprinter, an electronic device for text communication over a telephone line, that is designed for use by persons with hearing or speech difficulties. Other names for the device include teletypewriter, TTY, textphone (common in Europe), and minicom (United Kingdom).
The typical TDD is a device about the size of a typewriter or laptop computer with a QWERTY keyboard and small screen that uses LEDs or an LCD screen to display typed text electronically. In addition, TDDs commonly have a small spool of paper on which text is also printed — old versions of the device had only a printer and no screen. The text is transmitted live, via a telephone line, to a compatible device, i.e. one that uses a similar communication protocol.
Special telephone services have been developed to carry the TDD functionality even further. In certain countries there are systems in place so that a deaf person can communicate with a hearing person on an ordinary voice phone using a human relay operator. There are also "carry-over" services, enabling people who can hear but cannot speak ("hearing carry-over," a.k.a. "HCO"), or people who cannot hear but are able to speak ("voice carry-over," a.k.a. "VCO") to use the telephone.
The term TDD is sometimes discouraged because people who are deaf are increasingly using mainstream devices and technologies to carry out most of their communication. The devices described here were developed for use on the analog Public Switched Telephone Network . They do not work well on the new internet protocol (IP) networks. Thus as society increasingly moves toward IP based telecommunication, the telecommunication devices used by people who are deaf will not be TDDs. In the US for example, the use of the term TDD is thus discouraged to avoid confusion with these analog devices being referred to as TTYs.
Read more about Telecommunications Device For The Deaf: Other Devices For Hearing Impaired, Etiquette, Relay
Famous quotes containing the words device and/or deaf:
“One good reason for the popularity of “reductionism” among the philosophical outposts of the Western Establishment is that it can be, and is, used as a device for trying to take the wind, so to speak, out of the sails of Marxism.... In essence reductionism is a kind of anti-Marxist caricature of Marxist determinism. It is what anti-Marxists pretend that Marxist determinism is.”
—Claud Cockburn (1904–1981)
“O never give the heart outright,
For they, for all smooth lips can say,
Have given their hearts up to the play.
And who could play it well enough
If deaf and dumb and blind with love?”
—William Butler Yeats (1865–1939)