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.
On this page:
Rationale
Individuals who use screen reading software can find it hard to hear the speech output if there is other audio playing at the same time. This difficulty is exacerbated when the screen reader's speech output is software based (as most are today) and is controlled via the same volume control as the sound. Therefore, it is important that the user be able to turn off the background sound. Note: Having control of the volume includes being able to reduce its volume to zero.
Required development techniques
Compliance with this checkpoint requires at least one of the following techniques to be met.
These techniques are defined in the WCAG 2.0 Level A Success Criterion for Guideline 1.4.2 (link resides outside of ibm.com).
- Auto turn off: Playing a sound that turns off automatically within three seconds.
- Control at top: Providing a control near the top of the Web page that turns off sounds that play automatically.
- User request: Playing sounds only on user request.
Examples for General developers
1. Auto turn off: Playing a sound that turns off automatically within three seconds.
To comply with this technique, the following example must be implemented.
Example 1
A Web page opens with a brief musical introduction and then goes silent – similar to the booting of an operating system or with spoken instructions on how to get started such as: "To begin, press the enter key."
2. Provide a control near the top of the Web page that turns off sounds that play automatically.
To comply with this technique, the following example must be implemented.
Example 2
A web page contains embedded media (audio, video, etc) that begins to play once the page is loaded. The page would have "Pause" and / or "Stop" buttons that give the user control over media.
3. Playing sounds only on user request
To comply with this technique, the following example must be implemented.
Example 3
A Web page from a bird watching society has a looping background sound of a woodpecker singing. There are also sounds of wind, trees and other birds. The sounds do not start automatically. Instead, the Web content provides a link at the top of the page to allow the user to start the sounds manually. The button says "Turn sounds on." After pressing the "turn sounds on" button, the sounds are heard. The user is then presented with an option to "turn sounds off."
A link is provided to a sound file that includes the sounds of the birds. The link text says, "Hear the song of the pileated woodpecker (mp3)."
Recommended development techniques
The techniques above are required; the following techniques are recommended to enhance accessibility:
1. Provide a site-wide preference to turn off audio in addition to providing a control near the top of the Web page that turns off sounds that play automatically.
The JKRowling.com site contains a set of accessibility tools at the top of the page that allow the user to customize their experience, including muting all sounds.
Required test techniques
The following manual test techniques are required to test this checkpoint.
Required accessibility verification test techniques:
Use the following accessibility verification test (AVT) to validate the Web content. It is recommended that these tests be performed in order.
| Action | Result |
|---|---|
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Verify the compliance criteria for this technique as follows.
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Pass:
Fail:
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©2009 IBM Corporation
Last updated May 28, 2009.
W3C Recommendation 11 December 2008: http://www.w3.org/TR/WCAG20/ (link resides outside of ibm.com)
Copyright 1994-2009 W3C (Massachusetts Institute of Technology, European Research Consortium for Informatics and Mathematics, Keio University), All Rights Reserved.