Goal
Make prerecorded audio-only content easier to understand by reducing distracting background sounds.
Success Criterion · WCAG 1.4.7
Low or No Background Audio
For prerecorded audio-only content that contains primarily speech in the foreground, background sounds are at least 20 decibels lower than foreground speech or can be turned off.
Level AAAWCAG 2.0Perceivable1.4 · Distinguishable
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What to do
Ensure background audio is low enough (or removable) so speech is clear, or provide an option to turn off background sounds.
Why it matters
Background sounds can make speech hard to understand for people who are hard of hearing or have auditory processing challenges.
Success criterion
What WCAG 1.4.7 requires
Summarized directly from the official Understanding document so teams can quote the requirement accurately.
For prerecorded audio-only content that (1) contains primarily speech in the foreground, (2) is not an audio CAPTCHA, and (3) is not vocalization intended to be primarily musical expression such as singing or rapping, at least one of the following is true: (a) No background sounds. (b) The background sounds can be turned off. (c) The background sounds are at least 20 decibels lower than the foreground speech content, with the exception of occasional sounds that last for only 1 or 2 seconds.
Intent
Why WCAG created this requirement
- Background audio can mask speech and reduce comprehension.
- The criterion targets speech-dominant audio-only content.
- It excludes CAPTCHAs and music-focused vocalization (singing/rapping).
Benefits
Who gains when you pass
- Hard of hearing users can better understand spoken content.
- Users with auditory processing disorders can follow speech without competing audio.
- Non-native speakers can understand speech more clearly.
- Users in noisy environments benefit from clearer foreground audio.
Why it matters
User impact when this criterion fails
Summaries drawn from the Understanding document help you socialize impact statements with product stakeholders.
Speech may be unintelligible when mixed with loud music or sound effects.
Users may miss critical information in podcasts, announcements, or instructional audio.
Users may experience fatigue from trying to parse speech through background noise.
Exception guidelines
Use the WCAG 1.4.7 exceptions correctly
Document the rationale for each exception and note which alternative support you provide.
Audio CAPTCHA
Audio CAPTCHAs are excluded from this requirement.
Requirement
If the audio is a CAPTCHA, this criterion does not apply.
Musical vocalization
Singing or rapping where vocalization is primarily musical expression is excluded.
Requirement
If the content is primarily musical expression, this criterion does not apply.
Overview
For speech-focused prerecorded audio-only content, background sounds must not interfere with understanding. Provide clean speech, allow turning off background sounds, or ensure background is at least 20 dB lower than speech (except brief sound effects).
- If you cannot eliminate background sounds, provide a separate “speech-only” track or a toggle to reduce/remove background.
- 20 dB lower is a substantial reduction; typical “ducking” techniques may help.
- Short incidental sounds (1–2 seconds) are allowed as exceptions.
- This applies to audio-only content; video content is handled by other success criteria.
Reference: All summaries and highlights originate from Understanding WCAG 1.4.7 and the W3C quick reference.
Fast facts
- Conformance level
- Level AAA
- WCAG version introduced
- WCAG 2.0
- Principle
- Perceivable
- Guideline
- 1.4 · Distinguishable
Examples
Make success tangible for teams
Share pass/fail snapshots to coach designers, engineers, QA, and content authors.
Podcast intro music
Pass
Intro music fades out quickly and speech is mixed clearly; sustained background music is kept very low.
Fail
Background music plays throughout at near-speech level, making words hard to understand.
Instructional audio
Pass
Speech-only track is provided; background effects can be turned off.
Fail
Sound effects play continuously behind instructions with no option to disable.
Brief sound effects
Pass
Occasional 1-second chime plays between segments while speech remains clear.
Fail
Long ambient sound bed competes with speech for entire recording.
Evidence to keep
Document conformance decisions
Capture artifacts for VPATs, procurement reviews, and regression testing.
- Maintain an audio inventory with mix notes and whether speech-only versions exist.
- Document how background-audio toggles are presented and operated.
- Store production guidelines for acceptable speech/background level differences.
Official resources
Deep dives and supporting material
Keep these links handy when writing acceptance criteria or responding to audits.
Understanding 1.4.7
Official W3C interpretation, techniques, and intent for Low or No Background Audio.
Quick Reference 1.4.7
Filterable list of sufficient techniques and failures.
Technique G56
Providing a mechanism to turn off background sound.
Technique G55
Providing background sounds at least 20 dB lower than foreground speech.
Implementation checklist
Capture progress and blockers
- Inventory prerecorded audio-only content that is primarily speech.
- Audit mixes for background levels relative to speech.
- Produce a clean mix with no background sounds when feasible.
- If background is needed, provide a toggle or alternate track to turn it off/reduce it.
- Ensure background is at least 20 dB below speech for sustained background audio.
- Document any brief sound effects as “occasional” and keep them under 1–2 seconds.
Testing ideas
Prove conformance with evidence
- Identify speech-focused prerecorded audio-only content.
- Listen for background sounds that compete with speech.
- Verify one condition is met: no background, background can be turned off, or background is sufficiently low.
- If a toggle is provided, verify it is accessible and works reliably.
- Spot-check audio levels with an audio meter when possible.
- Verify excluded categories (CAPTCHA, singing/rapping) are correctly classified.
Related success criteria
More from Distinguishable (1.4)
WCAG 1.4.1Use of ColorLevel AWCAG 1.4.2Audio ControlLevel AWCAG 1.4.3Contrast (Minimum)Level AAWCAG 1.4.4Resize TextLevel AAWCAG 1.4.5Images of TextLevel AAWCAG 1.4.6Contrast (Enhanced)Level AAAWCAG 1.4.8Visual PresentationLevel AAAWCAG 1.4.9Images of Text (No Exception)Level AAAWCAG 1.4.10ReflowLevel AAWCAG 1.4.11Non-text ContrastLevel AAWCAG 1.4.12Text SpacingLevel AAWCAG 1.4.13Content on Hover or FocusLevel AA