Read Aloud (Desktop)

With EPUB files, users can freely switch between reading, listening or doing both at the same time using the Read Aloud feature.

In publications containing pre-recorded audio, Thorium Desktop will play the audio tracks embedded in the file.

Otherwise, it will fallback to synthesized speech provided by the operating system.

Controlling playback

To enable the Read Aloud feature and start playback, click on the Activate Read Aloud button represented by a speaker icon.

Clicking on the button will replace the Activate Read Aloud and the Settings button with expanded controls for playback that include:

• Play/Pause
• Stop
• Next/Previous item
• Settings

Clicking on the Pause button will pause the playback and keep these expanded controls at the top of the screen.

Clicking on the Stop button will stop the playback and remove these expanded controls.

The behavior of the Next and Previous buttons can change based on:

• how the publication has been authored for pre-recorded audio
• or user settings for synthesized voices

For synthesized voices, users can decide to either use skip to the next paragraph or sentence.

In the case of pre-recorded audio, some publications may also use word-by-word highlighting and navigation.

Settings

Synthesized speech (TTS)

When using synthesized speech, Thorium Desktop provides deep customization options for audio playback and highlighting.

By default, Thorium Desktop will use:

• 1x for playback rate
• the main language of the publication to filter synthesized voices
• and the highest quality voice available on your device

Language and voice will automatically switch when the publication contains fragments in another language that have been properly marked up by the publisher.

Please refer to the section dedicated to the installation of additional voices, as this will greatly improve your listening experience.

Selecting another voice and/or language

If the language has been incorrectly documented by the publisher, you can always override it and select another one using the list of languages.

This will automatically update the list of voices and push forward voices from your preferred region based on the settings of your operating system (for example British English vs US English).

Playback rate

In order to control the reading speed of a synthesized voice, Thorium Desktop offers a Playback Rate setting that can be adjusted between 0.5x and 6x.

Some voices can be distorted when using very low or very high values, so make sure that you try different voices in such cases.

Captions / clean view (🎤 karaoke-style)

In addition to the default view (which displays a page or a page spread), Thorium Desktop also provides a karaoke-style mode that can be turned on by clicking on Captions/Clean view.

This reading mode provides a radically different reading experience where:

• the text of the current chapter is scrolled automatically
• a ruler is used to display the current sentence
• and word by word highlighting with a yellow background

This mode works best with high contrast themes such as Dark, Contrast 1 and Contrast 2. Please refer to our section dedicated to display settings to learn more about reading themes.

Skippability

A publication can contain auxiliary content, such as footnotes, endnotes and pagebreaks.

If you’d like to skip these elements while using the Read Aloud feature, click on Skippability in Settings.

Continuous play

By default, Read Aloud will go through the entire publication.

If you’d like to change this behavior and automatically pause playback after every item, click on Disable continuous play.

While using this preference, click on the Previous and Next button to resume playback.

Splitting text into paragraphs and sentences

By default, Thorium Desktop splits text into sentences. This means that while using read aloud, the entire sentence will be highlighted.

This option can be turned off by disabling Split TTS Text in the Read Aloud settings.

This setting also impacts navigation using the Next/Previous buttons.

Customizing highlights

The following styles are available in settings for highlighting:

• Solid background (default for sentences)
• Underline (default for words)
• Outline
• Mask
• Mask block

All of these options can be applied at a sentence and/or world level. To select another combination, click on the list labeled TTS Highlight Style.

In addition to these different styles, 8 different colors are also available. Sentences and words can use different colors.

Pre-recorded audio

When a publication contains pre-recorded audio, Thorium Desktop will use it by default.

The following settings are available in this case:

• Playback Rate
• Captions/clean view
• Skippability
• Disable continuous play
• Ignore pre-recorded audio, use TTS

Most of these settings behave similarly to their synthesized voice counterpart.

If you prefer using synthesized voices over pre-recorded audio:

• Make sure to stop the playback first
• Click on the Read Aloud Settings button (headphone icon)
• Click on Ignore pre-recorded audio, use TTS

Installing additional synthesized voices

We highly recommend installing additional voices on your system, to expand your options and improve the overall quality of your listening experience.

Voice availability is directly tied to the operating system and version that you’re using.

Please refer to the following help pages for Windows and macOS.

Windows

• Installing additional voices on Windows
• List of voices available in Windows 10/11

macOS

• Installing additional voices on macOS

   

Keyboard shortcuts for Read Aloud