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Audio and video

Do not autoplay sound

• Rule: no-autoplay-audio
• Severity: Moderate
• WCAG level A

Why it matters

Audio that starts by itself talks over a screen reader, which is the only way some people can use the page at all. They cannot find the control to stop it because they cannot hear it.

How to fix it

1. Do not autoplay. If you must, start muted.
2. Where sound plays for more than three seconds, provide a pause or mute control at the very start of the page.
3. Respect prefers-reduced-motion for the video half of the same decision.

In markup

<video src="promo.mp4" autoplay></video>

<video src="promo.mp4" autoplay muted controls></video>

The requirement behind it

This rule is one way of failing the following WCAG 2.2 success criteria. The W3C, which writes the standard, explains each of them:

• 1.4.2 Audio Control (opens in new tab) — WCAG level A

Further reading

Deque University on no-autoplay-audio (opens in new tab)

Deque maintains axe-core, the open-source engine our scanner runs. Their page documents the rule as the engine implements it.

Automated checks find failures a browser can prove. They cannot judge whether a caption is accurate, whether an alt text is useful, or whether a page can be operated end to end with a keyboard — those need a person.