Glossary

Search results

Adaptive Multi-Rate Codec(also: AMR, AMR Codec, AMR-NB)

A family of audio codecs used in mobile telephony to encode voice for transmission. AMR-NB (narrowband) operates at 300-3,400 Hz with bit rates from 4.75-12.2 kbps, while AMR-WB (wideband, also called HD Voice) extends to 50-7,000 Hz at 6.6-23.85 kbps. AMR-WB is adopted by 3GPP…

Hearing Aid Compatibility(also: HAC, HAC Rating)

Federal Communications Commission (FCC) requirements and ratings for telephones to work effectively with hearing aids and cochlear implants. HAC standards address acoustic coupling (how well the phone works with hearing aid microphones) and telecoil coupling (magnetic signal…

Interactive Voice Response(also: IVR, Voice Response System)

A telephony technology that allows users to interact with automated systems using voice commands or keypad input. IVR systems are particularly valuable for accessibility in low-income settings because they work with any phone (including basic feature phones), require no internet…

Mean Opinion Score(also: MOS, MOS Score)

A standardized measure of perceived audio or video quality, rated on a scale from 1 (bad) to 5 (excellent). In telecommunications research, MOS is commonly used to assess speech quality as experienced by listeners. Participants rate samples, and scores are averaged to produce…

Narrowband Audio(also: NB Audio, Standard Definition Voice)

Audio transmission limited to the frequency range of approximately 300-3,400 Hz, which has historically been the standard for telephone networks (PSTN). While sufficient for basic speech intelligibility, narrowband audio excludes higher frequency consonant sounds that aid speech…

Packet Loss(also: Network Packet Loss, Data Loss)

The failure of data packets to reach their destination during network transmission, common in VoIP and mobile telephony. Packet loss causes audio dropouts, distortion, and reduced intelligibility. Research shows that 20% packet loss can render voice telephony essentially…

Remote interpreting(also: Video remote interpreting, VRI, Remote sign language interpreting)

The provision of sign language interpretation or other communication access services through video technology, where the interpreter is located in a different physical space from the deaf or hard of hearing person. Remote interpreting uses networked video connections to link…

Speech Intelligibility(also: Speech Recognition Score, Word Recognition)

A measure of how well speech can be understood by a listener, typically expressed as the percentage of words or sentences correctly identified under specific listening conditions. Speech intelligibility is affected by factors including audio bandwidth, background noise, signal…

Telecoil(also: T-Coil, Telephone Coil, Induction Coil)

A small copper coil inside a hearing aid or cochlear implant processor that picks up magnetic signals and converts them to sound. Telecoils allow hearing device users to receive audio directly from telephones, loop systems, and other compatible devices while reducing background…

Telecommunication equity(also: Communication equity, Functional equivalence)

The principle that people with disabilities should have access to telecommunications services that are functionally equivalent to those available to people without disabilities. For deaf users, this means video calling capabilities (for sign language) should be treated as…

Telecommunications Device for the Deaf(also: TDD, TTY, Text Telephone)

A specialized device that enables text-based telephone communication for people who are deaf or hard of hearing. TDDs transmit typed text over telephone lines using acoustic coupling or direct connection, requiring compatible devices at both ends of the conversation. While TDDs…

Video Conferencing(also: Videoconferencing, Video Teleconferencing, Video Call)

Real-time visual and audio communication between two or more people at different locations using video cameras, displays, and network connections. Video conferencing has significant accessibility implications: for Deaf and hard-of-hearing sign language users, it must provide…

Video Phone(also: Videophone, VP)

A telecommunications device that enables real-time video and audio communication between two or more parties. For Deaf and hard of hearing people, video phones are essential communication tools that allow conversation in sign language over distance, providing functional…

Video Relay Service(also: VRS)

A free, subscriber-based telecommunications service regulated by the Federal Communications Commission (FCC) in the United States that enables deaf individuals who use sign language to make phone calls to hearing individuals through a sign language interpreter via video link.…

Video intelligibility(also: Signal intelligibility, Visual signal clarity)

The degree to which a video signal can be perceived and understood by the viewer, determined by technical parameters including frame rate, bit rate, spatial resolution, and codec quality. Video intelligibility is distinct from comprehension — a viewer may perceive clear hand…

Video relay service(also: VRS)

A telecommunications service that enables deaf and hard-of-hearing sign language users to communicate with hearing people via telephone through a video link with a sign language interpreter. The deaf caller signs to the interpreter via video, and the interpreter speaks to the…

Voice over IP(also: VoIP, Internet Telephony, IP Telephony)

Technology that enables voice communication over internet protocol networks rather than traditional telephone lines. VoIP applications such as Skype, Zoom, and Teams allow voice and video calls over the internet at low cost. For accessibility, VoIP presents both opportunities…

Voice over Internet Protocol(also: VoIP, IP Telephony, Internet Calling)

Technology that enables voice communication over internet networks rather than traditional telephone lines. VoIP converts voice signals into digital packets transmitted over IP networks, enabling features like video calling, lower costs, and flexible integration with other…

Voice over LTE(also: VoLTE, LTE Voice, HD Voice)

A standard for transmitting voice calls over 4G LTE mobile networks using IP-based protocols rather than legacy circuit-switched networks. VoLTE typically uses the AMR-WB codec, enabling wideband HD voice quality that significantly benefits people with hearing loss. The improved…

Voicemail(also: Voice Mail, Voice Messaging)

Voicemail is a telecommunications service that records an audio message from a caller when the called party is unavailable, for later retrieval by the recipient. Accessibility considerations include: reliance on hearing to listen to messages (a barrier for Deaf and…

20 results.