Glossary

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Talking Head(also: Virtual Talking Head, Animated Face, 3D Talking Head)

A talking head is a computer-generated 3D or 2D animated representation of a human face and articulatory system that produces visible speech movements synchronised with audio output. In accessibility and speech therapy contexts, talking heads are particularly valuable because…

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…

Tonal Language(also: Tone Language)

A language in which pitch variations at the word or syllable level distinguish meaning, so that the same sequence of consonants and vowels can have entirely different meanings depending on the tone used. Languages like Mandarin Chinese, Thai, and Vietnamese are fully tonal,…

Tracked Captions(also: Speaker-following captions, Dynamic captions)

Captions that move dynamically within the video frame to stay near the current speaker's face or mouth, rather than remaining anchored at a fixed position (typically the bottom of the video). Tracked captions reduce the visual effort required for Deaf and Hard-of-Hearing viewers…

Transcription(also: Speech-to-Text Transcription, Real-Time Transcription)

The process of converting spoken language into written text, either in real time or after the fact. In accessibility contexts, transcription services provide communication access for deaf and hard of hearing individuals by producing text versions of spoken content in classrooms,…

Transcripts(also: Transcript, Text Transcript)

A written, text-based representation of spoken audio or audiovisual content. WCAG 2.1 success criterion 1.2.1 (Audio-only and Video-only Prerecorded) requires an alternative for time-based media — typically a transcript — for pre-recorded audio-only content such as podcasts,…

Typographic Encoding(also: Visual Typography Mapping)

The practice of using typographic properties—such as font size, weight, color, spacing, opacity, and baseline shift—to encode non-textual information within written content. In accessibility contexts, typographic encoding is used to represent paralinguistic speech features in…

VR-ASL(also: Virtual Reality American Sign Language)

A simplified adaptation of American Sign Language (ASL) designed for use in virtual reality environments where current controller tracking technology cannot capture the full range of hand and finger movements required for standard ASL. VR-ASL modifies or substitutes signs to…

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 Remote Interpreting(also: VRI)

A fee-based service that provides sign language interpretation via video conferencing technology, where the interpreter is located remotely rather than physically present with the deaf and hearing participants. VRI is commonly used when two of the three parties (the deaf person,…

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…

Visual Attention Split(also: Split Attention, Divided Visual Attention)

The cognitive challenge of needing to divide visual focus between two or more sources of information simultaneously. For deaf and hard of hearing people, visual attention split is a pervasive accessibility barrier: they must look at captions or a sign language interpreter while…

Visual Layout Customization(also: Layout Customization, Video Layout Arrangement)

The ability for users to rearrange, resize, reposition, lock, or remove visual elements in a digital interface to suit their individual needs. In videoconferencing, visual layout customization is critical for d/Deaf and hard of hearing users, who may need to enlarge the…

Visual Speech Aid(also: Speech Reading Aid, Visual Communication Aid)

A visual speech aid is an assistive device or system that converts auditory speech information into visual form to help individuals with hearing impairments follow spoken conversation. These aids may display text (as in captioning systems), phonetic symbols, lip-shape cues,…

Visual dispersion(also: Visual splitting, Divided visual attention)

The cognitive challenge faced by deaf and hard of hearing people when they must simultaneously monitor multiple visual information sources, such as an instructor, presentation slides, a sign language interpreter or captions, and their own notes. Because deaf individuals receive…

Visuocentric Design(also: Visual-First Design, Deaf-Centric Design)

An approach to interface and content design that prioritizes visual communication and spatial organization, particularly for users of visual languages like sign languages. Visuocentric design recognizes that deaf and hard of hearing users process information visually rather than…

Wearable Technology(also: Wearables, Wearable Devices)

Electronic devices designed to be worn on the body, such as smartwatches, fitness trackers, smart glasses, and haptic wristbands. In accessibility contexts, wearable technology offers unique advantages for delivering notifications and information through multiple sensory…

Wide-Range Achievement Test(also: WRAT, WRAT-5, WRAT sentence comprehension)

A standardised achievement test used to measure basic academic skills, including word reading, sentence comprehension, spelling, and math computation. In accessibility research, the WRAT sentence-comprehension sub-test has been validated as a measure of English literacy for Deaf…

Word Error Rate(also: WER)

A metric used to evaluate the accuracy of automatic speech recognition (ASR) and captioning systems, calculated as the number of word-level errors (insertions, deletions, and substitutions) divided by the total number of words in the reference transcript. Lower WER indicates…

d/Deaf(also: Deaf, deaf, Big D Deaf)

A convention used to distinguish between two meanings of the word deaf. Uppercase "Deaf" refers to people who identify as culturally Deaf and are part of the Deaf community, sharing a common language (sign language), values, and social norms. Lowercase "deaf" is an audiological…