Text-to-Speech Deep Dive

Overview

Text-to-Speech (TTS) converts written text to spoken audio and highlights what is being read. This deep dive covers all available settings and use cases.

Who benefits most: Students with dyslexia, visual processing difficulties, attention challenges, or anyone who learns better by listening.

---

All Settings Explained

Voice Selection

Choose from voices available on your system:

Setting	Options	Default
Voice	System voices (varies by OS)	A voice that runs on your device

Read Aloud starts with a voice that runs on your device. Chrome also offers online voices, such as the “Google” voices on a computer. An online voice sends the text being read to the company that runs it (Google or Microsoft), so the voice picker labels each one with who it sends your text to. Choose one only if you are happy for that text to go there.

Finding voices:

• Windows: Settings → Time & Language → Speech
• Mac: System Preferences → Accessibility → Spoken Content
• Chromebook: Settings → Accessibility → Text-to-Speech

Tips:

• Some voices sound more natural than others
• Try several voices to find one you like
• Download additional voices from your OS settings

---

Speed Controls

Setting	Range	Default	Description
Rate	0.5x - 2.0x	1.0x	How fast text is read. One-press buttons set 0.5x, 1x, 1.5x or 2x
Pitch	0.5 - 2.0	1.0	Voice pitch (higher/lower)
Volume	0 - 100%	100%	TTS audio volume

Speed recommendations:

User Need	Recommended Speed
Learning new content	0.8x - 1.0x
Familiar content review	1.2x - 1.5x
Proofreading own work	0.7x - 0.9x
Language learners	0.6x - 0.8x

---

Highlighting

Setting	Options	Default
Highlight While Reading	On/Off	On
Highlight colour	8 choices: Yellow (High Contrast), Bright Yellow, Gold, Light Green, Sky Blue, Light Pink, Plum, Khaki	Bright Yellow (#FFEB3B)
Highlight opacity	10% - 100%	70%
Word by Word	On/Off	Off

By default AssisT highlights the block of text being read. Turn on Word by Word to highlight each word as it is spoken, which is best for following along closely.

---

Read on click

Controls how much is read when you click text with Read Aloud on.

Setting	Options	Default
Read on click	This paragraph / This section / Whole page (skip menus)	This paragraph

Option	Behaviour
This paragraph	Reads the paragraph or list item you clicked
This section	Reads the whole article or section that contains it
Whole page (skip menus)	Reads the main content, without navigation, headers, footers and sidebars

For a section or the whole page, the page scrolls to keep the text being read in view. There is no switch for this.

Tip: Use This paragraph for focused reading, Whole page (skip menus) for hands-free listening while you do something else.

---

Highlight sync method

Shown when Word by Word is on. It controls how word highlighting stays in sync with the voice.

Setting	Options	Default
Highlight sync method	Boundary events / Timer	Boundary events

Option	How It Works
Boundary events	Highlights update on boundary events fired by the speech engine — the best sync with Chrome built-in voices
Timer	Highlights advance on a fixed timer — more consistent across voices that don’t fire boundary events reliably

Tip: If word highlights seem out of sync with the voice, switch to Timer.

---

Highlight speed

Shown when Word by Word is on.

Setting	Range	Default
Highlight speed	0.25× – 4×	2×

Higher values move the highlight along faster.

---

Step-by-Step Setup

Basic Setup

1. Click AssisT icon in toolbar
2. Open the Reading group
3. Toggle Read Aloud ON
4. Test by clicking a paragraph on any page

Optimised Setup for Different Needs

For dyslexia:

1. Turn on Word by Word
2. Set speed to 0.8x - 1.0x
3. Choose a high-contrast highlight colour (yellow or green)

For ADHD:

1. Set speed to 1.0x - 1.2x
2. Set Read on click to This section, so one click reads on without you
3. Choose a bright highlight colour

For language learning:

1. Set speed to 0.6x - 0.8x
2. Turn on Word by Word
3. Choose a clear, natural voice

---

Common Use Cases

Proofreading Your Own Writing

Settings:

• Speed: 0.7x - 0.9x (slower catches errors)
• Highlighting: Word by Word on
• Read on click: This paragraph

How it helps: Hearing your writing read aloud reveals awkward phrasing, missing words, and repetition that your eyes skip over.

---

Studying Long Documents

Settings:

• Speed: 1.0x (adjust to comfort)
• Read on click: This section
• Highlight While Reading: On

How it helps: Reduces eye fatigue, allows multitasking (follow along or listen only), and provides dual-channel learning (visual + auditory).

---

Reading Before Sleep

Settings:

• Speed: 0.8x
• Volume: 50-70%
• Highlight While Reading: Off (screen off)

How it helps: Listen without screen light. Combine with a Screen Color Overlay or turn screen off entirely.

---

Following Along with Physical Text

Settings:

• Speed: 0.9x - 1.0x
• Highlight While Reading: Off
• Read on click: This paragraph

How it helps: Use TTS as audio guide while reading printed textbook. Pause and resume as needed.

---

Troubleshooting

No Sound Playing

Solutions:

1. Check system volume isn’t muted
2. Verify TTS is enabled in AssisT popup
3. Try a different voice in settings
4. Check Chrome sound permissions for the website
5. Restart Chrome

Voice Sounds Robotic

Solutions:

1. Download better voices from OS settings
2. Try different available voices
3. Adjust pitch setting slightly (0.9 or 1.1)
4. On Windows: Install neural voices from Settings

Highlighting Not Working

Solutions:

1. Verify Highlight While Reading is on
2. Check if page uses unusual text rendering
3. Try refreshing the page
4. Some PDFs may not support highlighting

TTS Stops Unexpectedly

Solutions:

1. Page may have lost focus — click back on page
2. Content may have ended — select new content
3. Try pressing Ctrl+Shift+Space to resume if it was paused
4. Refresh page if problem persists

Wrong Language Being Used

Solutions:

1. Text may be in different language than expected
2. Manually select voice that matches content language
3. Some voices only support specific languages

---

Equations

By default a maths equation in the page is either skipped or read out as a run of symbols, which tells a listener almost nothing. With the Equation read-aloud companion feature on, equations join the ordinary reading flow instead: they are spoken as maths, in sequence with the surrounding sentences, and the synchronised highlight tracks through them the way it tracks through text.

It is on by default. Its switch, Read equations aloud, is in the popup’s Reading group.

Maths Support, in the Reading group, is the related setting for reading numbers on the page and for the on-page calculator.

---

Mind Maps

Read aloud also works inside the mind map editor. Alt+R speaks a branch using the same voice, rate and pitch you set here, and highlights the node being read. See the Mind Map guide.

---

Keyboard Shortcuts

Shortcut	Action
Ctrl+Shift+Space	Pause/Resume TTS
Ctrl+Shift+S	Stop TTS

While something is being read, Space also pauses and resumes, + and - make it faster or slower, and Escape stops it. No shortcut starts a read: click a paragraph or use Read Page.

---

For Educators & Parents

Setting Up TTS for Students

1. Test voice options together — Student preference matters
2. Start with defaults — Adjust only if needed
3. Set appropriate speed — Slower for new content, faster for review
4. Keep Highlight While Reading on — Visual tracking helps most learners

Monitoring Usage

TTS doesn’t track or report usage. To check if students are using it effectively:

• Ask students to demonstrate their settings
• Observe during study sessions
• Check if comprehension improves with TTS use

Classroom Implementation

• TTS works on most educational websites
• Compatible with Canvas, Moodle, Google Classroom
• Works offline with an on-device voice (online voices need a connection)
• Does not read the document text inside Google Docs, Sheets and Slides
• No additional logins or accounts needed

---

Related Features

• Reading Help — TTS overview
• Dyslexia Reading Modes — Combine with TTS
• User Profiles — Pre-configured TTS profiles