Telecommunication Devices for the Deaf

-TTY TTYs (also called Telecommunication Devices for the Deaf (TDD) and text telephones) are used for two-way text conversation over a telephone line. They are the primary tool used by deaf people (and some hard of hearing people) for telephone conversation. Other visual telecommunications technologies and services, such as Internet chat and messaging, email, e-paging, and fax and e-mail are also used in telecommunications by people who are deaf or hard of hearing.
-TRS
Telecommunications relay services (TRS) provide voice telephone users and people who are deaf, hard of hearing, or speech-disabled to communicate over a regular telephone line. TRS is mandated by the Americans with Disabilities Act and is regulated by the Federal Communications Commission. There have been many new improvements in TRS in the last several years. These improvements give users choices that make TRS calls more natural and "functionally equivalent" to voice telephone communications.
-Video relay service Using a high-speed Internet connection or ISDN, a video connection is established; a qualified sign language interpreter relays the conversation with the voice telephone party.
-CapTel
Captioned Telephone is a new product of Ultratec, being tested in several states. CapTel is an innovative service in which the operators repeat the words of the hearing party into an automatic speech recognition system for rapid transcription. Voice and data are carried on one line so that the hard of hearing or deaf user can monitor the speech as well as see the transcription. The CapTel phone is set up for "dial through" so that the user does not need to dial the relay service first.
-ASR
Automatic speech recognition is the most successful and accurate of these applications. It is currently making a use of a technique called "shadowing" or sometimes called "voicewriting." Rather than have the speaker's speech directly transcribed by the system, a hearing person