WCAG 1.4.2 Audio Control

What it asks

Sound that starts without being asked gets in the way of people who listen to the page through a screen reader. The screen reader speaks over the top of the page’s own audio, and the person cannot hear either. This rule says that any audio that plays automatically for more than 3 seconds must come with one of two things: a way to pause or stop it, or a way to control its volume separately from the system volume.

The 3 seconds is a limit on how long the sound may run before a control is needed. A short chime can play without one. A background track, an autoplaying video with sound or a talking advert cannot. The control has to be for this sound. A note telling people to use their computer’s volume control does not count, because turning that down also silences the screen reader.

The W3C recommends the simpler path: do not start sound automatically at all. A play button, or a video that starts muted, avoids the whole problem. This is also one of four non-interference criteria. A page that fails it can stop someone using the rest of the page, so every page has to meet it, even content that is otherwise left out of a conformance claim.

Its official name is success criterion 1.4.2 Audio Control, at Level A. It was added in WCAG 2.2, under guideline 1.4 Distinguishable and the principle Perceivable. The W3C’s normative text says, in part:

“If any audio on a web page plays automatically for more than 3 seconds, either a mechanism is available to pause or stop the audio, or a mechanism is available to control audio volume independently from the overall system volume level.”

From WCAG 2.2, W3C. Full explanation: Understanding 1.4.2 Audio Control.

Who it helps

Screen reader users above all. A screen reader is speech, and speech competes with any other sound. If the page is playing music, the person has to find the control to stop it while unable to hear the screen reader telling them where it is.

People who find unexpected sound hard to cope with, including some people with attention or cognitive disabilities, and people using screen magnification who cannot see where the sound is coming from.

What passes and what fails

These pass

• A video that plays automatically but starts muted, with sound only when the person turns it on.
• A background music track with a pause button in the first few controls on the page.
• An autoplaying welcome message that lasts under 3 seconds.
• A hero video with its own volume slider, separate from the system volume.

These fail

• A background video with an audio track that plays on load and has no pause or mute control.
• A third-party advert that starts playing sound in a slot the page does not control.
• A music track that starts on arrival, with the only advice being to turn down the computer’s volume.
• A video with autoplay and no controls, muted or custom pause button.

The control counts wherever it is, but a control near the top of the page is far more useful. A screen reader user has to reach it while the sound is playing. The W3C also notes that browsers increasingly block autoplay with sound, which does not make a page pass: the markup still asks for it, and some browsers and settings will allow it.

How to test it by hand

1. Open the page with the sound on and wait. Note anything that starts playing by itself: audio, video with sound, adverts, chat sounds and background music.
2. Time it. Anything that stops by itself within 3 seconds passes.
3. For anything longer, look for a pause, stop or mute control for that sound, or a volume control that affects only that sound.
4. Check that the control is easy to reach with the keyboard, and reasonably early in the page.
5. Repeat with a screen reader running, which is the situation the rule exists for, and note whether you could find the control while the sound was playing.
6. Check the markup for autoplay on audio and video elements, and for embedded players set to start automatically.

What automated testing can decide

What a machine can decide

A tool can list the audio and video on a page and read what the page says about each item: whether it is set to play automatically, whether it is muted, whether it has controls, and how long it is where the page states so. An element that is set to play sound automatically for more than 3 seconds with no control is a defect that can be read from the page.

What it cannot

A tool cannot hear the page. A video file may state no length, a player from another site may hide everything behind its own frame, and a track may be silent for its first minute. Whether a browser actually honours an autoplay request also varies by browser and by the person’s settings, so what the page asks for and what plays are not always the same thing. A custom pause button that is not marked as such takes a person to find.

How Dreven handles it

Dreven finds the audio, video and embedded players on your pages and shows you what each one does about sound, autoplay and controls. A reviewer decides each result.

A page with no media is recorded as not applicable, with the list of what was found as the evidence. Every result is one of four: passed, failed, not applicable or can’t tell.

No automated check makes a site conform. In Dreven, a person reviews the results and signs the report.

Related criteria

• 1.4.7 . The AAA rule on background sound behind speech.
• 2.2.2 Pause, Stop, Hide (Level A). Moving, blinking or auto-updating content needs a pause, stop or hide control.
• 1.2.2 Captions (Prerecorded) (Level A). Recorded video with sound needs captions.
• 2.1.1 Keyboard (Level A). The pause or volume control must work from the keyboard.

Questions people ask

All WCAG 2.2 criteria, in plain words