1.4.7 Low or No Background Audio

Level: AAA | Principle: Perceivable | Since: WCAG 2.0 | Automation: Manual

What This Means

For prerecorded audio content that primarily contains speech, background sounds must be either absent, at least 20 decibels lower than the foreground speech, or able to be turned off entirely.

A 20 dB difference means the background is roughly four times quieter than the speech. This ensures that people with hearing impairments can distinguish speech from background noise. Background music, ambient sounds, and sound effects that compete with speech make it much harder for these users to understand the content.

Audio that is purely musical (no speech) is exempt from this requirement. The focus is specifically on speech-based audio where understanding the words is the point.

Who This Affects

Hard of hearing users — difficulty separating speech from background noise is one of the most common hearing challenges
Users with auditory processing disorders — background noise makes speech comprehension significantly harder
Older adults — age-related hearing loss especially affects the ability to filter background noise
Non-native speakers — background sounds make it harder to follow speech in a second language

Common Pitfalls

1. Background music competing with narration

<!-- Bad: music track at same volume as narration -->
<audio controls>
  <source src="podcast-with-loud-music.mp3" type="audio/mpeg">
</audio>

<!-- Good: music is 20dB lower than speech, or separate toggle -->
<audio controls>
  <source src="podcast-quiet-music.mp3" type="audio/mpeg">
</audio>
<p><a href="podcast-no-music.mp3">Download version without background music</a></p>

2. No option to disable background audio

<!-- Bad: embedded video with baked-in background sounds -->
<video src="tutorial.mp4" controls></video>

<!-- Good: provide a speech-only version -->
<video src="tutorial.mp4" controls></video>
<p>
  <a href="tutorial-speech-only.mp4">Watch speech-only version (no background audio)</a>
</p>

How to Test

Play all prerecorded audio content that primarily contains speech (podcasts, narrations, interviews).
Listen for background music, ambient sounds, or sound effects competing with the speech.
Assess whether background audio is noticeably quieter than speech (at least 20 dB difference). If unsure, open the audio file in Audacity and compare the waveform levels.
Check if a mechanism exists to turn off background sounds (e.g., a speech-only version download link).
Pass: Background audio is at least 20 dB below speech levels, absent entirely, or can be turned off by the user.
Fail: Background audio competes with speech, is not at least 20 dB quieter, and no speech-only alternative is provided.

How to Fix

Mix audio so that background sounds are at least 20 dB below speech levels
Provide an alternate version with no background audio at all
If using background music, keep it minimal and well below speech volume
Offer a toggle or separate download for a speech-only track
During recording, minimize ambient noise and record speech in a quiet environment