Audio content with speech in the foreground meets the contrast thresholds set out in WCAG Success Criteria 1.4.7.


Example 1 — EPUB 3
<meta property="schema:accessibilityFeature">
Example 2 — EPUB 2
<meta name="schema:accessibilityFeature"
Example 3 — Audiobooks
"accessibilityFeature": ["highContrastAudio"]


The highContrastAudio value is used when a publication contains audio with speech and there is low or no background noise. Low background noise is defined as a minimum 20dB difference between foreground speech and background sounds (see WCAG success criterion 1.4.7).

High contrast audio is helpful for users who are hard of hearing and have trouble separating foreground speech from background noise.

The requirement for low or no background noise does not apply to musical works where the background sound is integral to the presentation.

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