How Background Noise Affects Accessibility

August 8, 2021

The Web Content Accessibility Guidelines (WCAG) contain plenty of useful guidance for developing accessible media. Success criterion 1.4.7, “Low or No Background Noise,” is often overlooked — as we’ll discuss in a moment, it’s not necessary for A/AA levels of conformance — but it’s helpful for building better digital content.

Success criterion 1.4.7 applies to audio-only content and isn’t directly applicable to music, CAPTCHAs, or audio that doesn’t primarily contain speech. However, it’s important to understand how loud or repetitive background noises can create barriers for some people. For example:

  • Background noises can be distracting for people with certain neurocognitive differences. They may have trouble distinguishing speech from other audio.
  • People who speak multiple languages may need to remove background audio to understand the content, especially when the performer is speaking quickly.
  • People with hearing disabilities may want to boost the volume of the media without boosting the background noise.
  • In some situations — such as a crowded train, library, or shared office space — media with loud background noises might be annoying to other people.

Of course, background noises can also improve your video content, and some people can actually focus more effectively with background noise. Apple recently added a “Background Sounds" feature to its iOS operating system for that reason. Disabilities are a spectrum, and by providing people with options, developers can create media that attracts a wider variety of users.

Background Noise and WCAG Conformance

So, how does background audio affect WCAG conformance? That depends on your goals, but success criterion 1.4.7 doesn’t fall into accessibility testing under most circumstances.

WCAG success criteria are divided into three conformance levels: A, AA, and AAA. Websites that fulfill the A and AA criteria are usually considered sufficiently accessible, and most sites aim for A/AA conformance. The success criterion for background noise isn’t a factor for WCAG A/AA conformance. 

However, that doesn’t mean it’s not important to certain users. Accessibility improves the experience for your entire audience, and limiting background sounds (or giving users more control over audio) is certainly helpful. Understanding the goals of AAA criteria can also help you develop a more accessible approach.

Best Practices for Creating Accessible Media 

Developers should be aware of how audio affects users. Wherever possible, give people options; adding a slider that controls the volume of background audio will accommodate  users' preferences. 

When that’s not possible, WCAG success criteria 1.4.7 recommends keeping background sounds at least 20 decibels lower than the foreground speech content. That doesn’t apply to performative content — for instance, if your media contains a song, the singer doesn’t need to be 20 decibels louder than the backing music. It also doesn’t apply to short sounds that only last for a few seconds (for example, sound effects).

Some other tips:

  • Avoid high-pitched sounds and repeating patterns, which may be distracting or irritating.
  • Speakers should read content clearly and slowly, incorporating pauses between topics.
  • Write scripts with clear language, avoiding acronyms, jargon, and idioms.
  • Be thoughtful when adding background audio to videos and interactive media. For more detailed guidance, read our checklist for creating accessible videos.

Remember, accessibility isn’t just about conformance. Be mindful of the ways that real users interact with your site and consider the purposes of the success criteria in WCAG. Even if you’re not testing for certain criteria, learning about them can help you build better content that appeals to your entire audience. 

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