Text-to-Speech for Accessibility
• By Alexandria Accessibility Team
Text-to-speech helps people with dyslexia, ADHD, visual impairment, and learning disabilities by converting written text into spoken audio with synchronised word-by-word highlighting. A meta-analysis in PMC found TTS significantly improves reading comprehension for students with reading disabilities. Alexandria provides word-level highlighting, research-backed background colours, speed control from 0.5x to 5x, and neural voices.
Research-Backed Accessibility
Dyslexia-Friendly Background Colors
Based on the Rello & Bigham (2017) study with 341 participants. Warm colors significantly improved reading performance.
All presets maintain WCAG AAA contrast (7:1+). Available in the Alexandria web app settings.
Who Benefits from Text-to-Speech
Text-to-speech isn't just a convenience tool. For millions of people with reading challenges, visual impairments, or attention differences, it's a way to access information that would otherwise be difficult or exhausting.
Alexandria is designed with accessibility in mind. The combination of audio and synchronised word-by-word highlighting creates what researchers call "dual coding", engaging both auditory and visual processing pathways simultaneously.
Key Facts
Around 10% of the UK population is affected by dyslexia, with approximately 4% severely affected [British Dyslexia Association, 2024].
NICE estimates 3-4% of adults in England have ADHD, representing roughly 2.5 million people [NICE, 2026].
67.8% of blind and low-vision adults use third-party screen reader or TTS software [American Foundation for the Blind].
A meta-analysis of TTS studies found an average effect size of 0.35 for reading comprehension improvement in students with reading disabilities [PMC / NCBI, 2017].
70% of dyslexic middle school students showed greater reading comprehension with computer-based reading systems, with 40% showing gains of two to five grade levels [ATIA, 2020].
Text-to-Speech for Dyslexia
How TTS Helps with Dyslexia
Dyslexia affects how the brain processes written language. People with dyslexia can understand complex ideas and spoken language perfectly fine, but decoding written text takes significant mental effort.
Text-to-speech removes the decoding barrier. Instead of struggling to sound out words, you hear them while seeing them highlighted. This allows you to focus on comprehension rather than spending all your mental energy on the mechanics of reading.
Research Evidence
Multiple studies confirm TTS effectiveness for dyslexia. A meta-analysis published in PMC (National Institutes of Health) found an average effect size of 0.35 for reading comprehension improvement in students with reading disabilities using TTS [Raskind & Higgins, 2017, PMC5494021].
Bonifacci et al. (2022, Journal of Computer Assisted Learning) found that text-to-speech significantly reduced mind wandering in students with dyslexia compared to self-paced reading. Students were measurably more on-task and retained more information [doi: 10.1111/jcal.12624].
Research shows the combination of audio and visual highlighting is more effective than audio alone. Synchronised highlighting helps dyslexic readers track where they are in the text without losing their place.
Specific Features That Help
Word-by-word highlighting (not just sentence highlighting) helps dyslexic readers follow along without losing their place. Adjustable speed lets you start slower while your brain adjusts, then gradually increase. Natural-sounding voices reduce cognitive load compared to robotic voices. The ability to replay sections makes it easier to absorb complex passages.
Recommended Settings for Dyslexia
Start at 1x speed (normal speaking pace). Many people with dyslexia can eventually listen at 1.25x to 1.5x, but don't rush it. Use the word-level highlighting - this is critical for tracking. Choose a voice that sounds natural and clear to you. Use dyslexia-friendly fonts in your browser if available.
Text-to-Speech for ADHD
How TTS Helps with ADHD
ADHD affects attention regulation. Reading requires sustained focus on static text, which is where attention often drifts. Your eyes might scan the words, but your mind wanders to other thoughts.
Text-to-speech creates an external pacing mechanism. The audio keeps moving forward, pulling your attention along with it. The synchronized highlighting creates a visual anchor - even if your mind wanders briefly, the moving highlight helps you jump back in.
Research Evidence
Bonifacci et al. (2022, Journal of Computer Assisted Learning) also tested students with ADHD. Results showed that in the text-to-speech condition, students with ADHD demonstrated better reading comprehension and significantly reduced rates of mind wandering compared to traditional reading [doi: 10.1111/jcal.12624].
NICE estimates 3-4% of adults in England have ADHD, representing approximately 2.5 million people as of 2026 [NICE, 2026]. For this population, TTS provides an external pacing mechanism that helps maintain attention during extended reading sessions.
Why It Works for ADHD
Listening requires active engagement in a way that can help maintain attention. The audio moves at a consistent pace, preventing the "read the same sentence five times" problem. You can listen while doing something physical (walking, fidgeting) which helps many people with ADHD concentrate. The word highlighting provides a visual anchor when attention drifts.
Recommended Settings for ADHD
Experiment with speed. Some people with ADHD focus better at faster speeds (1.5x-2x) because it matches their natural processing speed. Others need slower speeds. Try listening while doing something mildly physical (walking, cleaning, organizing) - this helps many people with ADHD concentrate. Use the word highlighting as an anchor point. If you drift, the highlight shows you exactly where to tune back in.
Multitasking Benefits
Many people with ADHD report that listening to TTS while doing repetitive tasks (folding laundry, commuting, organizing) helps them both complete the task AND absorb the reading. The dual engagement prevents boredom-driven attention drift.
Text-to-Speech for Visual Impairment
How TTS Helps with Low Vision and Blindness
For people with visual impairments, text-to-speech provides access to written content that would otherwise require magnification, high contrast, or be completely inaccessible.
Alexandria works alongside traditional screen readers. While screen readers like JAWS and NVDA provide system-wide access, Alexandria offers a web-focused experience with natural voices and easy speed control for reading articles, emails, and web content.
Alexandria vs Traditional Screen Readers
Traditional screen readers (JAWS, NVDA, VoiceOver) provide system-wide access and navigation but can sound robotic and require significant training. Alexandria offers natural-sounding voices, easy speed control without complex keyboard commands, and works immediately without setup or training. However, screen readers provide broader system access (menus, buttons, forms) while Alexandria focuses on content reading.
Many visually impaired users use both: screen readers for navigation and forms, Alexandria for long-form reading where natural voices and speed control improve the experience.
Accessibility Considerations
Alexandria's interface is keyboard-navigable for screen reader users. The play button and speed controls can be accessed without a mouse. However, the extension requires some visual setup initially. Once configured, it can be used entirely by ear with keyboard shortcuts: Ctrl+Space to play/pause, Ctrl+Arrow keys to navigate, Ctrl+Brackets to adjust speed. All shortcuts are customisable in settings.
According to Research
67.8% of blind and low-vision adults use third-party screen reader or TTS software [American Foundation for the Blind]. Text-to-speech technology provides access to written information that would otherwise require significant magnification, high contrast settings, or specialist equipment.
Text-to-Speech for Learning Disabilities
Who This Helps
Learning disabilities that affect reading include dyslexia (difficulty decoding words), dysgraphia (difficulty writing), dyscalculia (affects reading numbers), auditory processing disorder (affects reading comprehension), and nonverbal learning disability (affects reading context).
TTS helps by separating comprehension from decoding. Students who understand content verbally but struggle with written text can access the same information through audio.
Research on Reading Disabilities
A meta-analysis of text-to-speech effectiveness for students with reading disabilities found that TTS significantly improved comprehension compared to silent reading. Students with various reading disabilities derived measurable benefit from TTS technology.
The research shows TTS is particularly effective when combined with visual highlighting - this dual-channel approach improves both comprehension and retention compared to audio or visual alone.
Educational Applications
Reading assignments and textbooks can be listened to instead of read visually. Research papers and articles become accessible without the reading struggle. Note-taking can happen while listening (focus on comprehension, not decoding). Test preparation allows students to review materials in an accessible format.
Text-to-Speech for English Language Learners
How TTS Helps ELL Students
Learning English involves two challenges: understanding meaning AND learning pronunciation. Text-to-speech helps with both by demonstrating correct pronunciation while showing the written word.
The synchronized highlighting connects written words to spoken sounds, helping learners map English spelling to pronunciation. This is particularly valuable for English, where spelling and pronunciation don't always match predictably.
Research on ELL and TTS
A systematic review on speech recognition and pronunciation found that TTS technology helps ELL students improve their pronunciation and literacy skills and makes reading difficult texts easier.
Synchronised highlighting connects written English to spoken sounds in real time, helping learners understand how English spelling maps to pronunciation. This is particularly useful given the inconsistency of English orthography.
Pronunciation Practice
Hear correct English pronunciation for new vocabulary. Listen at slower speeds while learning, then gradually increase. Use the highlight to connect written spelling to spoken sounds. Practice listening comprehension by removing the text and listening only.
The Science: Why TTS Works
Dual Coding Theory
When you both hear words and see them highlighted simultaneously, you engage two cognitive pathways: auditory processing and visual processing. This dual engagement creates stronger memory encoding than single-channel learning.
Research in cognitive psychology shows that dual coding improves retention and comprehension. You're not just reading or just listening - you're doing both, which creates multiple neural pathways to the same information.
Reduced Cognitive Load
For people with reading challenges, the mental effort of decoding text (turning letters into sounds into words into meaning) uses up cognitive resources that could be spent on comprehension.
TTS handles the decoding automatically, freeing up mental energy for understanding content. This is why many students report they can understand complex material via TTS that they struggled with when reading.
Active vs Passive Learning
Listening isn't passive when combined with highlighting. Your eyes track the highlighted word, your ears hear it, and your brain connects the two. This active coordination keeps you engaged with the material.
Research shows that TTS with highlighting keeps students more "on task" than traditional reading, particularly for students with ADHD or attention difficulties.
Research-Backed Dyslexia-Friendly Colors
Alexandria includes background color presets specifically designed to reduce visual stress and improve reading comfort for people with dyslexia and visual stress conditions.
The Science Behind Background Colors
A 2017 study by Rello & Bigham with 341 participants (89 with dyslexia) tested different background colors for digital reading. The findings were significant: warm colors like peach, cream, and sepia significantly improved reading performance compared to pure white or cool colors.
Visual stress (also called Meares-Irlen Syndrome) affects up to 46% of people with dyslexia. It causes symptoms like words appearing to blur, move, or flicker on the page. High-contrast patterns (black text on white) can overstimulate the visual cortex. Colored backgrounds reduce this cortical hyperexcitability.
What the British Dyslexia Association Recommends
The British Dyslexia Association Style Guide recommends avoiding pure white backgrounds because "white can appear too dazzling." They recommend cream or soft pastel colors with dark (not pure black) text. Alexandria's presets follow these evidence-based guidelines.
Alexandria's Research-Backed Presets
Cream (#FEF9E7): BDA-recommended warm tone with soft navy text. Gentle on eyes for extended reading.
Peach (#EDD1B0): The best performer in the Rello & Bigham study. Warm apricot background with dark brown text.
Sepia (#F4ECD8): Kindle-style warm tone familiar from e-readers. Reduces blue light exposure.
Mint (#E8F8F5): Cool alternative for users who prefer cooler tones, with dark teal text.
Dark (#1A1A1A): For low-light reading, with white (#FFFFFF) text for comfortable night reading.
All presets maintain WCAG AAA contrast ratios (7:1 or higher) while avoiding the harsh black-on-white that causes visual stress.
How to Use Background Presets
Open the Alexandria web app and click the settings gear icon. Under "Reading background," you'll see color preset buttons. Click any preset to instantly change the background. Your preference is saved automatically and applies to all future reading sessions. For the full research on color choices, see our guide at /dyslexia-colors.
How Alexandria Supports Accessibility
Alexandria was built with several accessibility considerations that make it particularly effective for people with reading challenges:
Word-Level Highlighting
Unlike some TTS tools that highlight entire sentences or paragraphs, Alexandria highlights individual words as they're spoken. This precise synchronization helps users track exactly where they are, which is critical for people with tracking difficulties (common in dyslexia) or attention challenges (ADHD).
Natural-Sounding Voices
Alexandria uses premium neural voices which sound significantly more natural than robotic voices. Research shows that natural voices reduce cognitive load and make listening less fatiguing.
More natural voices mean you can listen for longer periods without the mental exhaustion that comes from robotic speech.
Flexible Speed Control
Speed is adjustable from 0.5x (half speed, useful for language learners) to 3x (for experienced listeners). The speed changes instantly - no page reload or reconfiguration needed. You can slow down for complex passages and speed up for familiar material.
Keyboard Accessibility
All core functions work via keyboard: Ctrl+Space to play/pause, Ctrl+Arrow keys to skip forward/backward, Ctrl+Brackets to adjust speed. All shortcuts are customisable in settings. This keyboard access is important for people who struggle with mouse precision or prefer keyboard navigation.
Privacy for Sensitive Content
Alexandria automatically blocks itself on healthcare portals, educational portals with sensitive data, and other sites where privacy matters. For students using TTS for learning disabilities or medical documentation, this privacy protection is important.
Content is processed transiently and not stored long-term. Your reading material isn't building up in a database that could be accessed or leaked.
Cross-Platform Accessibility
Works on any website where you read: articles, documentation, emails, social media, research papers. No need to copy text to a separate app. Chrome extension integration means it's available wherever you browse. All accessibility features included - no feature limitations or paywalls for students with disabilities.
Getting Started with Alexandria for Accessibility
If you're using Alexandria specifically for accessibility needs, here's how to optimize your setup:
Initial Setup Recommendations
Install from Chrome Web Store (takes 30 seconds). Start at 1x speed - don't try to speed up immediately. Choose a voice that sounds clear and natural to you (try several). Enable keyboard shortcuts for hands-free control. Test on a familiar website first to get comfortable with the interface.
Building Up Speed (For All Users)
Week 1: Listen at 1x speed. Get comfortable with the basics. Week 2-3: Try 1.25x. Your brain adapts quickly. Week 4+: Experiment with 1.5x-2x for familiar material. Many users eventually listen at 2x-3x for most content, but there's no rush. Speed up gradually.
For Dyslexia Specifically
Keep highlighting enabled always. Track the highlighted word with your eyes even while listening. Start with shorter texts (articles, not textbooks) to build confidence. Use slower speeds for new or complex material. Increase speed as you get comfortable with the content type. Pair TTS with warm background colors for the full effect — see /dyslexia-colors for the research, and /reading-fonts for font and spacing settings.
For ADHD Specifically
Experiment with faster speeds (1.5x-2.5x) - many people with ADHD focus better when audio matches their natural processing speed. Listen while doing something mildly physical (walking, organizing). The movement helps maintain attention. Use keyboard shortcuts to quickly pause and restart without breaking flow. Try listening to shorter chunks (5-10 minute articles) rather than hour-long documents initially. See also our guide at /best/text-to-speech-for-adhd for ADHD-specific tool comparisons.
For Visual Impairment
Learn the keyboard shortcuts first (they work without seeing the interface). Ctrl+Space = play/pause. Ctrl+Right Arrow = skip forward. Ctrl+Left Arrow = skip back. Ctrl+[ = slower, Ctrl+] = faster. All shortcuts are customisable in settings. Adjust your screen reader settings to avoid conflicts with Alexandria's audio.