Glossary

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Speech Synthesis(also: Synthetic Speech, TTS Engine)

The artificial production of human speech by computer, most commonly used in text-to-speech (TTS) systems that convert written text into spoken audio. Speech synthesis is foundational to screen readers and other assistive technologies used by people with visual impairments and…

Speech Synthesis Markup Language(also: SSML)

Speech Synthesis Markup Language (SSML) is a W3C standard XML-based markup language for controlling the rendering of synthetic speech by text-to-speech (TTS) engines. SSML provides tags for specifying pronunciation, volume, pitch, speaking rate, emphasis, pauses, and voice…

Speech Synthesizer(also: Speech Synthesiser, Text-to-Speech Engine, TTS Engine)

Software or hardware that converts text into spoken audio output, producing artificial speech that can be used to read content aloud. Speech synthesizers are a fundamental component of many assistive technologies, including screen readers for blind users and augmentative and…

Speech Therapy(also: Speech-Language Therapy, Speech Pathology, Speech-Language Intervention)

Clinical intervention provided by speech-language pathologists (SLPs) to assess, diagnose, and treat speech, language, communication, and swallowing disorders. For speech sound disorders, effective treatment requires "frequent, high-intensity, individualized, and naturalistic"…

Speech User Interface(also: SUI, Voice User Interface, VUI)

A user interface that enables interaction with a computer or device primarily through spoken language rather than through physical input devices like keyboards, mice, or touchscreens. Speech user interfaces use speech recognition to interpret user commands and may provide…

Speech Visualization(also: Visual Speech Display, Speech-to-Visual Display)

Speech visualization refers to techniques that convert spoken language into visual representations to aid comprehension, particularly for individuals who are deaf or hard of hearing. These displays can range from real-time captioning and waveform displays to more abstract…

Speech and Language Therapist(also: SLT, Speech-Language Pathologist, SLP)

A healthcare professional who assesses, diagnoses, and treats communication and swallowing disorders. Speech and language therapists play a critical role in the assistive technology ecosystem by evaluating clients for AAC suitability, recommending appropriate communication…

Speech and Language Therapy(also: SLT, Speech-Language Pathology, SLP)

A healthcare discipline focused on assessing and treating communication difficulties including speech, language, voice, fluency, and swallowing disorders. Speech and language therapists work with people who stammer, those with dysarthria, aphasia, and other conditions affecting…

Speech disorder(also: Speech impairment, Communication disorder)

A condition that affects an individual's ability to produce speech sounds correctly or fluently, encompassing articulation disorders, fluency disorders, and voice disorders. Speech disorders are significant for digital accessibility because voice-controlled interfaces,…

Speech-Based Cursor Control(also: Voice Cursor Control, Speech-Driven Pointing)

A method of controlling a computer's pointing cursor using spoken voice commands rather than a mouse, trackpad, or other physical pointing device. Users speak directional commands (such as "move left," "move up") to start cursor movement and a stop command to halt it, then issue…

Speech-Based Cursor Movement(also: Voice-Controlled Cursor, Voice Cursor Control)

A technique for moving the on-screen cursor using voice commands rather than physical manipulation of a pointing device. Speech-based cursor movement systems typically use one of two approaches: discrete specification, where the user speaks a command to jump the cursor to a…

Speech-Based Navigation(also: Audio Navigation, Speech-Based Web Navigation)

A method of navigating digital content, particularly web pages, using synthesised speech output rather than visual display. In speech-based navigation, users listen to content read aloud sequentially and use keyboard commands to move between elements. This approach is inherently…

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…

Speech-Language Pathologist(also: SLP, Speech Therapist, Speech-Language Therapist)

A healthcare professional who assesses, diagnoses, and treats communication and swallowing disorders across the lifespan. In the context of accessibility, SLPs play a central role in AAC intervention — evaluating individuals for AAC needs, selecting appropriate devices and…

Speech-Language Pathology(also: SLP, Speech Therapy, Speech-Language Therapy)

A healthcare profession focused on the assessment, diagnosis, and treatment of communication disorders, speech disorders, language disorders, cognitive-communication disorders, and swallowing difficulties. Speech-language pathologists (SLPs) work with individuals across the…

Speech-Language Therapy(also: Speech Therapy, SLT, Speech-Language Pathology)

A clinical practice focused on assessing and treating communication disorders including speech, language, voice, fluency, and swallowing difficulties. Speech-language therapists (or speech-language pathologists) work with people who have aphasia, dysarthria, stuttering, voice…

Speech-Like Vocalization(also: SLV)

A sound produced by a person that can be phonetically transcribed based on the conventions of a spoken language, distinguishing it from non-speech-like vocalizations such as grunts, screeches, or vocal stereotypies. In speech development research, particularly for nonverbal or…

Speech-Reading(also: Lip-Reading, Lipreading, Visual Speech Perception)

The practice of understanding spoken language by visually interpreting the movements of the lips, face, tongue, and jaw of the speaker, along with contextual cues such as facial expressions and body language. Many deaf and hard of hearing people use speech-reading as one of…

Speech-language pathology(also: SLP, Speech therapy, Speech-language therapy)

Speech-language pathology is the clinical discipline concerned with the assessment, diagnosis, and treatment of communication and swallowing disorders, including speech sound production, language comprehension and expression, voice, fluency, and cognitive-communication skills.…

Speech-modulated Typography(also: Speech-driven Typography, Prosody-driven Typography)

A design technique in which the visual properties of text — typically font weight, width, or size on a variable-font axis — are modulated in real time by features extracted from a corresponding speech signal, such as pitch, loudness, rhythm, or an inferred emotional-arousal…

Speech-to-Sign Translation(also: Spoken Language to Sign Language Translation)

The process of automatically converting spoken language into sign language output, typically displayed through a signing avatar or animated character. Speech-to-sign translation involves three major components: automatic speech recognition to convert audio to text or semantic…

Speech-to-Speech(also: S2S, Speech-to-Speech Conversion)

A class of systems that transform one speech signal directly into another — for example, converting atypical input (whispered, dysarthric, accented, or cross-lingual speech) into clear, intelligible output in a target voice or language. Speech-to-speech systems differ from…

Speech-to-Text(also: STT, Speech Recognition, Automatic Speech Recognition)

Technology that converts spoken language into written text, enabling voice-based input for digital systems. In accessibility, speech-to-text serves multiple roles: it powers voice command interfaces for users who cannot use keyboard or touch input, generates real-time captions…

Speechreading(also: Lipreading, Lip Reading)

A communication method that relies on observing visual and contextual cues, primarily the movements of a speakers lips, face, and body, to understand spoken language. Speechreading is used by many d/Deaf and hard of hearing individuals as a supplement to other communication…

Speed Dial(also: One-touch Dialing, Quick Dial)

Speed dial is a mobile or landline phone feature that lets a user place a call to a preset contact by pressing one or two assigned digits rather than entering a full phone number. Originally introduced as a convenience feature, speed dial functions as a meaningful accessibility…

Speed-Accuracy Tradeoff(also: Speed-Accuracy Trade-off, SAT)

A fundamental principle of human motor control where increased movement speed leads to decreased accuracy, and vice versa. Users can choose to move quickly and accept more errors, or move slowly and carefully to minimize mistakes. In accessibility contexts, the speed-accuracy…

Speed-Comprehension Trade-off(also: Speed-Accuracy Trade-off in Reading)

An empirical pattern in readability research: typographic, layout, and presentation choices that increase reading speed often reduce comprehension accuracy, and vice versa. For example, sans-serif faces and shorter line lengths tend to support faster reading but may yield lower…

Spell Checker(also: Spellchecker, Spelling Checker)

Software that identifies and suggests corrections for misspelled words in text. Standard spell checkers often fail to catch errors made by people with dyslexia because dyslexic spelling errors differ from typical misspellings — they may include real-word substitutions (e.g.,…

Spina Bifida(also: Neural Tube Defect, Myelomeningocele)

A congenital birth defect in which the embryonic neural tube fails to close completely during development, resulting in an incompletely formed spinal cord. The severity ranges from mild (spina bifida occulta, often asymptomatic) to severe (myelomeningocele, where the spinal cord…

Spinal Cord Injury(also: SCI)

Damage to the spinal cord that results in temporary or permanent changes in motor function, sensation, or autonomic function below the level of injury. Depending on the location and severity, spinal cord injuries can cause paraplegia (lower body paralysis) or…

Spinal Cord Injury(also: SCI)

Damage to the spinal cord that results in partial or complete loss of motor function, sensation, or both below the level of injury. The location of injury along the spine determines which abilities are affected: injuries at higher vertebrae (e.g., C4-C5) affect more of the body,…

Spinal Cord Injury(also: SCI)

Damage to the spinal cord that results in loss of function, mobility, or sensation below the level of injury. Injuries are classified as complete (total loss of function below the injury) or incomplete (some function preserved). The higher the injury on the spinal cord, the more…

Spinal Muscular Atrophy(also: SMA)

Spinal Muscular Atrophy (SMA) is an autosomal recessive neurodegenerative disease characterized by degeneration of spinal cord motor neurons, atrophy of skeletal muscles, and generalized weakness. Affecting approximately 1 in 6,000-10,000 live births, SMA is the leading genetic…

Spinal Stenosis(also: Lumbar Stenosis, Cervical Stenosis)

A narrowing of the spaces within the spine that can put pressure on the nerves travelling through the spinal column. When spinal stenosis occurs in the cervical (neck) region, it can cause weakness, numbness, or tingling in the hands and arms, affecting fine motor control and…

Spindex(also: Speech Index)

An auditory navigation technique that uses the first letter of each word (spoken or synthesized) as an index to speed up list navigation. When scrolling through alphabetically ordered lists like contacts, a spindex plays the first letter of each item, allowing users to quickly…

Split Attention(also: Split-Attention Effect, Divided Attention)

A cognitive phenomenon in multimedia learning where users must divide their visual attention between multiple information sources presented simultaneously. In accessibility contexts, this is particularly challenging for Deaf and Hard of Hearing viewers of captioned videos, who…

Split Attention Effect(also: Split Attention)

A cognitive load phenomenon in multimedia learning where learners must divide visual attention between two or more sources of information that should be integrated - for example captions at the bottom of the screen and a diagram in the centre. The cost of switching and mentally…

Split Tap(also: Split Tapping)

A touchscreen interaction technique where the user holds one finger on a target element while tapping with a second finger to activate it. Split tap allows blind users to explore the screen with one finger to locate elements (hearing each one announced) and then tap elsewhere to…

Split-Attention Effect(also: Split Attention)

A cognitive load phenomenon that occurs when learners or viewers must divide their visual attention between multiple sources of information that are physically or temporally separated. In captioned media, the split-attention effect occurs when viewers must read captions while…

Split-Tap Gesture(also: Split Tap)

A two-finger touchscreen gesture where one finger holds position on an object while a second finger taps elsewhere on the screen to activate or select it. Originally developed for the Slide Rule screen reader, the split-tap gesture was adopted by mobile screen readers like…

Spoken Dialog System(also: SDS, Voice Dialog System, Conversational AI)

A computer system that uses speech as both input and output to conduct goal-oriented conversations with users. Unlike simple voice command systems, spoken dialog systems can handle multi-turn exchanges, track conversation context, manage misunderstandings, and adapt to user…

Spoken Dialogue System(also: SDS, Voice Dialogue System)

A computer system that communicates with users through spoken natural language, allowing them to interact via voice rather than visual or manual interfaces. Spoken dialogue systems are used in telecare, customer service, and home care applications, and are particularly relevant…

Spoken Web(also: World Wide Telecom Web, WWTW, Telecom Web)

An alternative web paradigm designed for people in developing regions who are excluded from the traditional World Wide Web by illiteracy, unaffordability, or lack of locally relevant content. In the Spoken Web, nodes are voice applications called VoiceSites that are created by…

Spoon Theory(also: Spoons)

A metaphor created by Christine Miserandino to explain the limited energy available to people living with chronic illness or disability. In this framework, each daily activity costs a certain number of "spoons" from a finite supply, and once spoons are depleted, the person…

Spoon theory(also: Spoons, Energy accounting)

A metaphor created by Christine Miserandino to explain the limited energy reserves experienced by people with chronic illness and disabilities. "Spoons" represent units of energy, and every activity — from getting dressed to attending a meeting — costs spoons. Once spoons are…

Sports Analytics(also: Data Analytics in Sports, Performance Analytics)

The use of data collection, statistical analysis, and technology to measure, track, and improve athletic performance, inform coaching decisions, develop game strategies, and enhance the spectator experience. In able-bodied sports, analytics has become a multi-billion dollar…

Spreadsheet Accessibility(also: Accessible Spreadsheets)

The design and implementation of spreadsheet documents and applications so they can be effectively used by people with disabilities, particularly screen reader users. Key considerations include consistent layout and structure, meaningful headers and labels, avoiding merged cells…

Stable Diffusion

An open-weights latent text-to-image diffusion model released by Stability AI in 2022. It operates by iteratively denoising a random latent tensor, conditioned on text embeddings produced by a frozen CLIP encoder, until the latent can be decoded by a VAE into a coherent image.…

Stable Systems of Access

Access ecosystems where a disabled person can reliably anticipate available resources, plan long-term, and accumulate stability over time. In a stable system, stakeholders are predictable, resources are consistently available, and the person can make informed decisions about…

Staff Notation(also: Stave Notation, Standard Music Notation)

The conventional Western system for writing music using five horizontal lines (a staff or stave) on which notes are placed at different vertical positions to indicate pitch, with various symbols for rhythm, dynamics, and expression. Staff notation is inherently graphical—unlike…