Glossary

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Single-Message AAC Device(also: BIGmack, Single-Switch Communicator, Voice Output Communication Aid)

A simple augmentative and alternative communication (AAC) device that records and plays back a single message when activated, typically via a large button or switch. Examples include the BIGmack Switch and similar products. These devices are often used as introductory AAC tools…

Speech Generating Device(also: SGD, Voice Output Communication Aid, VOCA)

An electronic device used in augmentative and alternative communication that produces speech output, either through pre-recorded messages or text-to-speech synthesis. Speech generating devices range from dedicated hardware devices (like the Accent1400) to software applications…

Speech Neuroprosthesis(also: Speech BCI, Speech Brain-Computer Interface)

A brain-computer interface that decodes neural activity associated with attempted or imagined speech and converts it into text, synthesized voice, or both. Speech neuroprostheses are designed for people with anarthria or severe dysarthria from ALS, brainstem stroke, locked-in…

Speech-Generating Device(also: SGD, Voice Output Communication Aid, VOCA)

An electronic AAC device that produces spoken output from text or symbol input, enabling people with speech disabilities to communicate verbally with others. Speech-generating devices range from dedicated hardware (such as Tobii Dynavox devices) to software applications running…

Step-by-Step Device(also: Sequential Message Device, Step-by-Step Communicator, SBS)

A simple, single-switch augmentative and alternative communication (AAC) device that stores a sequence of pre-recorded voice messages and plays them back one at a time with each button press. Step-by-step devices are categorised as "low-tech" or "mid-tech" AAC because they…

Switch Keyboard(also: Scanning Keyboard, On-Screen Scanning Keyboard)

A switch keyboard is a virtual keyboard interface designed for people with severe motor disabilities who cannot use a standard keyboard or pointing device. It works through a scanning mechanism: a cursor automatically moves across rows and columns of the keyboard, and the user…

Symbol-based AAC(also: Picture-based AAC, Pictographic AAC, Picture Communication Symbols)

Symbol-based AAC refers to augmentative and alternative communication systems whose vocabulary is represented by graphic symbols, line drawings, photographs, or pictograms rather than (or alongside) written words. Users select symbols on a paper board, a dedicated…

Technical Agency

Technical agency, in the context of augmentative and alternative communication (AAC), refers to an individual's ability to actively participate in and contribute to a conversation through direct actions such as speaking, gesturing, or vocalizing. It is distinguished from…

Text Gloss(also: Text Glosses)

In Augmentative and Alternative Communication (AAC), a text label or annotation associated with a visual symbol (such as an icon or pictogram) on a communication device. The text gloss serves two purposes: it provides a written description to help communication partners…

Trigram(also: 3-gram)

A sequence of three consecutive words used in statistical language modeling for word prediction. Trigram models predict the next word based on the two preceding words, capturing more context than simpler unigram (single word) or bigram (two word) models. In AAC word prediction,…

Turn Taking(also: Conversational Turn-Taking, Turn-Taking)

The pragmatic skill of alternating speaking and listening roles during conversation, including knowing when to speak, how long to speak, and how to signal readiness to yield or take a turn. Turn taking is a fundamental component of social communication that children typically…

Unaided AAC(also: Unaided Augmentative and Alternative Communication, Body-Based AAC)

The branch of Augmentative and Alternative Communication that relies solely on the user's body — gestures, facial expressions, vocalisations, manual signs, body orientation — without an external device. Unaided AAC is fast, always available, and naturally expressive; families,…

Unimodal Interface(also: Single-Mode Interface)

An interface that accepts input through only one mode or channel of interaction, such as keyboard-only, voice-only, or gesture-only input. In contrast to multimodal interfaces that combine multiple input methods, unimodal interfaces rely on a single input modality for command…

Visual Communication(also: VIC)

A method of conveying information, ideas, and meaning through visual elements such as images, icons, symbols, and pictographs rather than through spoken or written language. In accessibility contexts, visual communication systems are particularly important for people with…

Voice Cloning(also: Voice Synthesis Cloning, Personalized Text-to-Speech)

The use of machine-learning models to synthesise a target speaker's voice from a short reference recording, enabling text-to-speech output that sounds like that specific person. For accessibility, voice cloning has transformative potential: people whose voices are at risk of…

Voice Customization(also: Voice Personalization, Custom Voice)

The process of creating or modifying synthetic voices to match a user's preferences or identity, including attributes such as gender, age, pitch, breathiness, hoarseness, and speech variation. Voice customization is particularly important in accessibility for people with speech…

Widgit Symbols(also: Widgit Rebus, Widgit Literacy Symbols)

A commercial symbol set used in augmentative and alternative communication (AAC) and literacy support, developed by Widgit Software in the UK. Widgit Symbols are designed with consistent schematic representations that build on a core vocabulary, making them particularly suitable…

Word Prediction(also: Predictive Text, Word Completion)

A text input feature that suggests complete words based on the characters already typed, using language models to anticipate the most likely intended word. In assistive technology, word prediction is particularly valuable for single-switch users and people with motor…