1.4.7 Low or No Background Audio

1. What is the goal of this criterion?

You know the feeling: you’re listening to a podcast and suddenly can’t make out a word because dramatic music kicks in behind the speaker? For people with hearing loss, that’s not just annoying – it can make audio content completely unusable.

So the goal of Success Criterion 1.4.7 is clear: audio recordings with speech should be produced so that background sounds don’t drown out the spoken words. People who are hard of hearing should be able to distinguish speech from background music, noise or other distractions.

In short: when someone is speaking, it should be easy to hear – without needing exceptionally sharp ears.

2. What exactly does it require?

Specifically, it covers prerecorded audio-only content (so not videos) that consists mainly of speech. That could be podcasts, audiobooks, recorded interviews or talks.

For such content, at least one of the following must be true:

No background sounds: the recording contains only speech – no music, no ambient soundscape.

Background sounds can be turned off: users can switch off the background sounds and hear just the speech.

The 20 dB rule: background sounds are at least 20 decibels quieter than the foreground speech. According to the W3C, that makes them about four times quieter than the speech. Occasional sounds lasting only one or two seconds may be louder.

Not covered are:

• Audio CAPTCHAs and audio logos (such as a jingle used as a sonic trademark)
• Singing, rapping or other vocalization intended primarily as musical expression

A practical example: a corporate podcast with continuous background music must either do without the music, make it possible to turn the music off, or mix it at least 20 dB below the speech.

3. Why does it matter for accessibility?

Imagine you want to catch up on an important talk, but music keeps playing in the background – and your hearing isn’t perfect. What may be merely annoying for others makes the whole thing incomprehensible for you.

Low or no background audio makes content accessible because it:

• Helps people who are hard of hearing distinguish speech from other sounds
• Supports hearing aid users, since hearing aids often amplify speech and background alike
• Eases the load for people with attention deficits who struggle to focus on speech amid noise
• Helps people with cognitive disabilities focus on what matters
• Benefits everyone in noisy environments

And clear speech recordings are more pleasant for everyone – automatic transcription also tends to work more reliably with clean recordings.

4. How to meet the criterion

The good news: clear speech recordings are mostly a matter of preparation and mixing. Here are some proven tips:

When recording:

• Use a good microphone and record in a quiet environment
• Skip background music unless it’s really necessary
• Use music deliberately – as an intro, outro or in pauses without speech
• Do a test listen: is the speech easy to understand even in quiet passages?

In post-production:

• Remove background hiss and noise with audio software such as Audacity or Adobe Audition
• Use a compressor to even out speech levels
• If you want background music: mix it at least 20 dB below the speech
• Keep speech and music on separate tracks to stay flexible later

Technical implementation:

• Alternatively, offer a second version without background music, or a player with separate volume controls for speech and background
• Clearly indicate where users can turn the background music off
• Add a transcript – this also helps deaf and hard-of-hearing people (see Audio-only and Video-only (Prerecorded))

Tools:

• Audacity (free) for basic editing, noise removal and level metering
• Adobe Audition or Logic Pro for professional editing
• Specialized podcast tools such as Hindenburg or Descript

For audio that starts automatically on websites, Audio Control also applies.

5. Why this criterion matters for businesses

Success Criterion 1.4.7 is another case where accessibility isn’t an end in itself – it brings real benefits for your business.

1. Reach a wider audience

Clear speech makes your content usable for more people: people who are hard of hearing, hearing aid users, people in noisy environments and anyone who values good quality. You don’t lose listeners to poor intelligibility.

2. Strengthen a professional image

Clean audio signals professionalism and care. Podcasts, talks or e-learning content without distracting background noise come across as more competent and trustworthy.

3. Reuse content more easily

Clear speech recordings are easier to transcribe, caption, quote and repurpose for other formats.

Last but not least: the legal context. Level AAA is not required by the European Accessibility Act or by its German implementation, the Barrierefreiheitsstärkungsgesetz (BFSG) – the benchmark there is WCAG 2.1 Level AA via EN 301 549. The W3C also advises against requiring Level AAA as a general policy for entire sites. For podcasts and learning content, however, 1.4.7 is a worthwhile quality goal. This section is general information, not legal advice.

6. The success criterion in the W3C’s words

Success Criterion 1.4.7 Low or No Background Audio (Level AAA)

For prerecorded audio-only content that (1) contains primarily speech in the foreground, (2) is not an audio CAPTCHA or audio logo, and (3) is not vocalization intended to be primarily musical expression such as singing or rapping, at least one of the following is true:

• No Background: The audio does not contain background sounds.
• Turn Off: The background sounds can be turned off.
• 20 dB: The background sounds are at least 20 decibels lower than the foreground speech content, with the exception of occasional sounds that last for only one or two seconds.

Note: Per the definition of “decibel,” background sound that meets this requirement will be approximately four times quieter than the foreground speech content.

In short: in prerecorded audio-only content with speech, background sounds must either be absent, be possible to turn off, or be at least 20 dB quieter than the speech.