Glossary

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Digital Sheet Music(also: Electronic Sheet Music)

Musical scores displayed on electronic devices such as tablets, computers, or head-mounted displays rather than printed on paper. Digital sheet music offers accessibility advantages over print including the ability to magnify, adjust colors and contrast, invert colors for better…

Digital Signal Processor(also: DSP)

A specialised microprocessor designed to perform mathematical operations on digital signals in real time, such as filtering, compression, and pattern recognition. In assistive technology, DSPs are used in hearing aids to process and amplify sound, in speech recognition systems,…

Digital Talking Book(also: DTB, DAISY Digital Talking Book, Talking book)

A multimedia document format that synchronises text, audio narration, and navigation structure to provide accessible reading experiences for people who are blind, have low vision, or have print disabilities. Based on the DAISY (Digital Accessible Information System) standard,…

Digital Twin

A digital twin is a virtual replica of a physical object, space, or system that is updated in real time to mirror its real-world counterpart. In accessibility contexts, digital twins of physical environments can enable remote exploration and interaction with spaces — allowing…

Digital fabrication(also: Fab, Digital manufacturing)

The process of creating physical objects from digital designs using computer-controlled tools such as 3D printers, laser cutters, and CNC machines. In accessibility contexts, digital fabrication enables the creation of customised assistive devices tailored to individual needs —…

Digital mental health(also: E-mental health, Digital therapeutics)

The use of digital technologies including AI chatbots, mood tracking apps, and online therapeutic platforms to support mental health assessment, monitoring, and intervention. Designing accessible and explainable AI for digital mental health is particularly challenging because…

Direct Touch Mapping(also: DTM, Touch-to-Audio Mapping)

An interaction technique in accessible touchscreen interfaces where the physical position of a user's finger on the screen corresponds directly to a position within the underlying content, such as a data visualization. When applied to chart accessibility, direct touch mapping…

Directional Guidance(also: Navigation Guidance, Orientation Feedback)

Real-time feedback that helps users maintain correct positioning or navigate toward a target, commonly provided through audio cues (such as pitch changes) or haptic signals (such as vibration patterns). In accessible reading systems, directional guidance indicates when a user…

Disability Dongle

A term coined by disability advocate Liz Jackson describing a well-intentioned but ultimately useless technology solution created for disabled people by non-disabled people who have not engaged with the community they intend to serve. Disability dongles are typically conceived…

Disability dongle

A well-intentioned but impractical accessibility invention, typically created by non-disabled people, that fails to address the actual needs of disabled users. The term, coined by disability advocate Liz Jackson, critiques technologies designed without meaningful input from…

Disabled innovator(also: Disability-led innovation)

A disabled person who creates, develops, and disseminates technology or solutions that address accessibility needs, drawing on their lived experience and situated knowledge. Disabled innovators challenge the dominant paradigm where accessibility technology is designed "for"…

Discreet AAC(also: Discreet Assistive Communication, Wearable AAC)

Augmentative and alternative communication devices designed to be socially unobtrusive and visually inconspicuous, in contrast to traditional tablet-based AAC systems that are physically prominent and easily identifiable. Discreet AAC encompasses wearable technologies such as…

Disordered Speech(also: Pathological Speech, Atypical Speech)

Speech that differs from typical patterns due to motor, neurological, structural, or developmental conditions. Disordered speech encompasses conditions like dysarthria, apraxia, stuttering, and speech differences from cerebral palsy or Parkinson's disease. For accessibility,…

Displayless Interface(also: Screenless Interface, Eyes-Free Interface)

A displayless interface is a computer interaction system that operates without a visual display, relying instead on audio, speech, haptic, or other non-visual output modalities. These interfaces serve two overlapping user populations: individuals with visual impairments who…

Distant speech recognition(also: Far-field ASR, Far-field speech recognition)

Automatic speech recognition performed on audio captured by microphones positioned at a distance from the speaker (typically 2+ meters), rather than close-talk input from headsets or handheld devices. Distant speech recognition is significantly more challenging than close-talk…

Distraction Management(also: Distraction Reduction, Attention Support)

Strategies, tools, and design approaches that help users minimize unwanted interruptions and maintain focus on their intended tasks, particularly in digital environments. For people with ADHD, distraction management is a core accessibility need because the condition affects the…

Document Analysis(also: Document Image Analysis, DIA)

The process of automatically extracting structure, content, and meaning from document images or files, including layout detection, text recognition, and logical structure identification. In accessibility, document analysis is essential for converting print materials and…

Dragon NaturallySpeaking(also: Dragon Dictation, Dragon Speech Recognition, Nuance Dragon)

Dragon NaturallySpeaking is a commercial speech recognition software product, originally developed by Dragon Systems and later acquired by Nuance Communications (now part of Microsoft). It converts spoken words into text and computer commands, enabling hands-free computer…

DragonDictate(also: Dragon Dictate)

An early discrete speech recognition system developed by Dragon Systems that allowed users to control computers and dictate text by speaking one word at a time with brief pauses between words. Released in the early 1990s, DragonDictate was one of the first commercially viable…

Drone Accessibility(also: UAV Accessibility, Accessible Drone Piloting)

The design and adaptation of unmanned aerial vehicles (drones) and their control interfaces to be usable by people with disabilities. This includes providing alternative input methods such as voice commands, adapted controllers, and tangible interfaces, as well as multimodal…

Dual Channel Audio(also: Dual Audio Channel, Two-Channel Audio)

An audio configuration that provides two independent, simultaneous audio streams to a user, typically through separate channels in a headset. In assistive technology, dual channel audio is important for vision impaired users in call centre environments who need to hear screen…

Duxbury Braille Translator(also: Duxbury, DBT)

A commercial Braille translation software package (Duxbury Systems) widely used by transcribers and production agencies to convert print text and documents into contracted and uncontracted Braille, including specialised codes such as Nemeth for mathematics. Duxbury supports…

Dwell Activation(also: Dwell Click, Dwell Selection)

An input method where an action is triggered by maintaining focus on a target for a specified period of time (the dwell time). Commonly used with eye tracking and head tracking systems, dwell activation allows users to select items without needing to physically click. While…

Dwell Control(also: Dwell Click, Dwell Selection, Dwell-Time Activation)

An input method in which a user activates a target — such as a button, link, or key — by holding a pointer or gaze over it for a specified period of time rather than clicking or tapping. Dwell control is essential for users who interact via head tracking, eye tracking, or other…

Dwell Selection(also: Dwell Click, Dwell Time Selection, Hover Click)

An interaction technique where a user activates or selects an on-screen element by keeping a cursor, gaze point, or pointer within the target area for a specified duration (the dwell time), rather than clicking or tapping. Dwell selection is essential for people with motor…

Dwell Time(also: Gaze Dwell, Fixation Duration)

The length of time a user must maintain their gaze on a target element to trigger a selection in eye gaze technology systems. Dwell time is a critical parameter in gaze-based interfaces: too short and users make unintended selections (the "Midas touch" problem), too long and…

Dwell-Based Selection(also: Dwell Selection, Dwell Time Selection)

An interaction technique used in eye-gaze and head-tracking interfaces in which holding the cursor over a target for a fixed duration (the 'dwell time', typically 300-1000 ms) triggers a selection, replacing the click action that a mouse user would perform. Dwell-based selection…

Dynamic Content(also: Dynamic Web Content, Live Content)

Dynamic content refers to web page elements that change or update after the initial page load, either automatically (such as news tickers, stock prices, or chat messages) or in response to user interaction (such as search suggestions, form validation messages, or content loaded…

Dynamic Difficulty Adjustment(also: DDA, Adaptive Difficulty)

A system design approach that automatically or manually adjusts the precision, complexity, or challenge level of feedback and interaction based on the user's skill level and progress over time. Originally developed for video games to balance challenge and frustration, DDA has…

Dynamic Keyboard(also: Adaptive Keyboard, Self-Adjusting Keyboard)

An assistive technology concept in which a keyboard automatically adjusts its input parameters — such as key repeat rate, debounce time, and acceptance delay — based on the user's typing patterns and abilities. Dynamic keyboards were developed to reduce common typing errors…

Dynamic Programming(also: DP, DP Matching)

A mathematical optimization technique used in pattern recognition that breaks complex problems into simpler overlapping subproblems. In accessibility technology, dynamic programming matching (DP matching) is commonly used in sign language recognition and speech recognition…

E-Ink Display(also: Electronic Ink, E-Paper, Electronic Paper Display)

A display technology that mimics the appearance of ink on paper by using electrically charged particles to create images. E-ink displays are characterized by high readability in direct light, minimal glare, extremely low power consumption, and reduced eye strain compared to…

E-Tran Frame(also: Eye-Transfer Frame, Eye-Pointing Frame, ETRAN)

A low-technology augmentative and alternative communication (AAC) device consisting of a transparent frame or board that allows a person to communicate by directing their eye gaze toward symbols, letters, words, or colour-coded groups arranged on the frame. The communication…

E-textiles(also: Electronic Textiles, Smart Textiles)

E-textiles are textile objects that integrate electronic components such as sensors, lights, or actuators into their design. They combine traditional textile techniques (sewing, embroidery, weaving) with electronic circuitry, often using conductive yarn or thread to create…

EMG Switch(also: Electromyography Switch, Muscle Signal Switch)

An assistive technology switch that detects electrical signals produced by muscle contractions (electromyography) to generate a switch activation. EMG switches can detect even very small muscle movements, such as a slight facial twitch or jaw clench, making them suitable for…

EVITA(also: Enabling Visually Impaired Table Access)

A specialized table browser developed at the University of Manchester designed to enable visually impaired users to navigate, browse, and read HTML data tables non-visually in a manner analogous to how sighted readers interact with tables in print. EVITA provides keyboard-based…

Ear-EEG(also: Around-the-Ear EEG, cEEGrid)

Ear-EEG refers to electroencephalography (EEG) recorded using electrodes placed in and around the ear canal rather than on the scalp. Consumer-grade ear-EEG devices such as cEEGrid sensors are unobtrusive, easy to wear without hair preparation, and suitable for everyday…

Earcon(also: Auditory icon)

A brief, distinctive sound used in a user interface to convey information, status, or feedback non-visually. Earcons serve a similar function to visual icons but through the auditory channel. In accessible interfaces, earcons can augment or replace visual cues — for example, a…

Echolocation(also: Human echolocation, Active echolocation)

The ability to determine the location and characteristics of objects by emitting sounds and interpreting their echoes. While commonly associated with bats and dolphins, many blind and low-vision individuals develop echolocation skills for spatial navigation, using self-generated…

Edge enhancement(also: Edge detection, Contour enhancement)

An image processing technique that identifies and highlights the boundaries between objects in a visual scene, typically rendering them as bright lines against a dark background or overlaying them on the original image. For people with low vision, edge enhancement can make…

EdgeWrite(also: Edge Write)

A gestural text entry method that uses the physical edges and corners of a square input area to guide character formation. Unlike traditional handwriting recognition that analyzes the full path of a stroke, EdgeWrite recognizes characters based on the sequence of corners hit,…

Educational Technology(also: EdTech, Learning Technology, Instructional Technology)

The use of technological tools and resources to facilitate teaching and learning. In accessibility contexts, educational technology encompasses assistive tools designed to support students with disabilities, such as screen readers, refreshable Braille displays, auditory graphing…

Eigenfaces

A computer vision technique for face recognition that uses Principal Component Analysis to represent faces as a linear combination of standardized face components (eigenvectors derived from a training set of face images). Developed by Turk and Pentland in 1991, Eigenfaces was…

Eight-Dot Braille(also: 8-Dot Braille, Computer Braille)

An extended braille system that adds two additional dots below the standard six-dot braille cell, creating a 2x4 matrix of eight dots that can represent 256 unique characters (compared to 64 in standard 6-dot braille). Eight-dot braille is primarily used with refreshable braille…

Electrical Muscle Stimulation(also: EMS, Neuromuscular Electrical Stimulation, NMES)

A technique that uses electrical impulses delivered through surface electrodes to elicit muscle contractions. EMS is used therapeutically for muscle re-education, spasticity management, and rehabilitation, and has been explored in HCI as an output modality — for example, guiding…

Electroencephalography(also: EEG)

A non-invasive method of recording electrical activity of the brain using electrodes placed on the scalp. In assistive technology, EEG is the primary sensing technology behind brain-computer interfaces (BCIs), which allow people with severe motor impairments such as paralysis or…

Electroencephalography(also: EEG)

A non-invasive method of recording electrical activity in the brain using electrodes placed on the scalp. EEG is fundamental to most consumer and research brain-computer interfaces because it is relatively inexpensive, portable, and safe compared to invasive neural recording…

Electrolarynx(also: Artificial Larynx, Electronic Larynx)

A handheld, battery-powered device that produces voice for people who have lost their larynx. The device is held against the neck or cheek and generates vibrations that travel through the throat tissues into the oral cavity, where the user shapes the vibration into speech using…

Electrolarynx(also: Artificial Larynx, Electric Larynx, EL Device)

A handheld battery-powered device that produces mechanical vibrations to generate speech for people who have lost their larynx (voice box), typically due to laryngeal cancer surgery. The device is held against the neck or cheek, where it transmits vibrations through the tissue…

Electromagnetic Actuation(also: EM Actuation)

A method of producing physical movement using electromagnetic fields generated by electric coils. In accessibility contexts, electromagnetic actuation is used to move tactile elements — such as magnetic markers or braille pins — to create dynamic tactile displays and interfaces…