ACT-Rules Community

Audio element content has text alternative

  • Rule Type:composite
  • Rule Id: e7aa44
  • Last modified: Jun 03, 2022
  • Accessibility Requirements Mapping:
    • 1.2.1 Audio-only and Video-only (Prerecorded) (Level A)
      • Learn More about 1.2.1 Audio-only and Video-only (Prerecorded)
      • Required for conformance to WCAG 2.0 and later on level A and higher.
      • Outcome mapping:
        • Any failed outcomes: success criterion is not satisfied.
        • All passed outcomes: success criterion needs further testing.
        • An inapplicable outcome: success criterion needs further testing.
    • G158: Providing an alternative for time-based media for audio-only content
      • Learn More about technique G158
      • Not required to conformance to any W3C accessibility recommendation.
      • Outcome mapping:
        • Any failed outcomes: technique is not satisfied.
        • All passed outcomes: technique needs further testing.
        • An inapplicable outcome: technique needs further testing.
  • Input Rules:

Description

This rule checks that audio elements have a text alternative available.

Applicability

This rule applies to any non-streaming audio element for which at least one of the following is true:

Expectation

For each test target, the outcome of at least one of the following rules is passed:

Assumptions

This rule assumes that the language of each test target can be correctly determined (either programmatically or by analyzing the content), and sufficiently understood.

Accessibility Support

There are no major accessibility support issues known for this rule.

Background

Bibliography

Test Cases

Passed

Passed Example 1

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This audio element has a play button, and there is a transcript of the audio.

<html lang="en">
	<audio src="/test-assets/moon-audio/moon-speech.mp3" controls></audio>
	<p>
		The above audio contains the following speech: We choose to go to the moon in this decade and do the other things,
		not because they are easy, but because they are hard, because that goal will serve to organize and measure the best
		of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to
		postpone, and one which we intend to win, and the others, too.
	</p>
</html>

Passed Example 2

Open in a new tab

This audio element has a play button, and the text on the page labels the audio as an alternative.

<html lang="en">
	<p>
		A part of a speech by John F. Kennedy: We choose to go to the moon in this decade and do the other things, not
		because they are easy, but because they are hard, because that goal will serve to organize and measure the best of
		our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to
		postpone, and one which we intend to win, and the others, too.
	</p>
	<p>
		You can also listen to the audio file below to hear the above part of the speech.
	</p>
	<audio src="/test-assets/moon-audio/moon-speech.mp3" controls></audio>
</html>

Passed Example 3

Open in a new tab

This audio element autoplays, and there is a transcript of the audio.

<html lang="en">
	<audio src="/test-assets/moon-audio/moon-speech.mp3" autoplay controls></audio>
	<p>
		The above audio contains the following speech: We choose to go to the moon in this decade and do the other things,
		not because they are easy, but because they are hard, because that goal will serve to organize and measure the best
		of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to
		postpone, and one which we intend to win, and the others, too.
	</p>
</html>

Failed

Failed Example 1

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This audio element has a play button but has an incorrect transcript.

<html lang="en">
	<audio src="/test-assets/moon-audio/moon-speech.mp3" controls></audio>
	<p>
		The above audio contains the following speech: We are going to the North Pole in this decade with puppies, not
		because they are easy, but because they are cute, because that goal will serve to organize and measure the best of
		our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to
		postpone, and one which we intend to win, and the others, too.
	</p>
</html>

Failed Example 2

Open in a new tab

This audio element autoplays but the text transcript is not visible on the page.

<html lang="en">
	<p style="display: none;">
		A part of a speech by John F. Kennedy: We choose to go to the moon in this decade and do the other things, not
		because they are easy, but because they are hard, because that goal will serve to organize and measure the best of
		our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to
		postpone, and one which we intend to win, and the others, too.
	</p>
	<p>
		You can also listen to the audio file below to hear the above part of the speech.
	</p>
	<audio src="/test-assets/moon-audio/moon-speech.mp3" autoplay controls></audio>
</html>

Inapplicable

Inapplicable Example 1

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This audio element does not autoplay or have a play button.

<html lang="en">
	<audio src="/test-assets/moon-audio/moon-speech.mp3"></audio>
</html>

Inapplicable Example 2

Open in a new tab

This audio element is labeled as an alternative by text on the same page, but the controls are not visible on the page.

<html lang="en">
	<p>
		A part of a speech by John F. Kennedy: We choose to go to the moon in this decade and do the other things, not
		because they are easy, but because they are hard, because that goal will serve to organize and measure the best of
		our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to
		postpone, and one which we intend to win, and the others, too.
	</p>
	<p>
		You can also listen to the audio file below to hear the above part of the speech.
	</p>
	<audio src="/test-assets/moon-audio/moon-speech.mp3" controls style="display: none;"></audio>
</html>

Inapplicable Example 3

Open in a new tab

This a element links to an audio file, but there is no audio element on this page.

<html lang="en">
	<p>
		A part of a speech by John F. Kennedy: We choose to go to the moon in this decade and do the other things, not
		because they are easy, but because they are hard, because that goal will serve to organize and measure the best of
		our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to
		postpone, and one which we intend to win, and the others, too.
	</p>
	<p>
		<a href="/test-assets/moon-audio/moon-speech.mp3">Download the speech as MP3</a>
	</p>
</html>

Glossary

Attribute value

The attribute value of a content attribute set on an HTML element is the value that the attribute gets after being parsed and computed according to specifications. It may differ from the value that is actually written in the HTML code due to trimming whitespace or non-digits characters, default values, or case-insensitivity.

Some notable case of attribute value, among others:

  • For enumerated attributes, the attribute value is either the state of the attribute, or the keyword that maps to it; even for the default states. Thus <input type="image" /> has an attribute value of either Image Button (the state) or image (the keyword mapping to it), both formulations having the same meaning; similarly, "an input element with a type attribute value of Text" can be either <input type="text" />, <input /> (missing value default), or <input type="invalid" /> (invalid value default).
  • For boolean attributes, the attribute value is true when the attribute is present and false otherwise. Thus <button disabled>, <button disabled="disabled"> and <button disabled=""> all have a disabled attribute value of true.
  • For attributes whose value is used in a case-insensitive context, the attribute value is the lowercase version of the value written in the HTML code.
  • For attributes that accept numbers, the attribute value is the result of parsing the value written in the HTML code according to the rules for parsing this kind of number.
  • For attributes that accept sets of tokens, whether space separated or comma separated, the attribute value is the set of tokens obtained after parsing the set and, depending on the case, converting its items to lowercase (if the set is used in a case-insensitive context).
  • For aria-* attributes, the attribute value is computed as indicated in the WAI-ARIA specification and the HTML Accessibility API Mappings.

This list is not exhaustive, and only serves as an illustration for some of the most common cases.

The attribute value of an IDL attribute is the value returned on getting it. Note that when an IDL attribute reflects a content attribute, they have the same attribute value.

Focusable

An element is focusable if one or both of the following are true:

Exception: Elements that lose focus during a period of up to 1 second after gaining focus, without the user interacting with the page the element is on, are not considered focusable.

Notes:

  • The 1 second time span is an arbitrary limit which is not included in WCAG. Given that scripts can manage the focus state of elements, testing the focusability of an element consistently would be impractical without a time limit.
  • The tabindex value of an element is the value of the tabindex attribute parsed using the rules for parsing integers. For the tabindex value to be different from null, it needs to be parsed without errors.

Included in the accessibility tree

Elements included in the accessibility tree of platform specific accessibility APIs are exposed to assistive technologies. This allows users of assistive technology to access the elements in a way that meets the requirements of the individual user.

The general rules for when elements are included in the accessibility tree are defined in the core accessibility API mappings. For native markup languages, such as HTML and SVG, additional rules for when elements are included in the accessibility tree can be found in the HTML accessibility API mappings (working draft) and the SVG accessibility API mappings (working draft).

For more details, see examples of included in the accessibility tree.

Programmatically hidden elements are removed from the accessibility tree. However, some browsers will leave focusable elements with an aria-hidden attribute set to true in the accessibility tree. Because they are hidden, these elements are considered not included in the accessibility tree. This may cause confusion for users of assistive technologies because they may still be able to interact with these focusable elements using sequential keyboard navigation, even though the element should not be included in the accessibility tree.

Instrument to achieve an objective

An HTML element that when activated allows an end-user to achieve an objective.

Note: Any rule that uses this definition must provide an unambiguous description of the objective the instrument is used to achieve.

Background About Instrument for Instrument to achieve an objective

This definition is a more restrictive version of WCAG's definition of mechanism, notably restricting it to the current document. WCAG has a note that "The mechanism needs to meet all success criteria for the conformance level claimed." This includes all the level A criteria such as Success Criterion 2.1.1 Keyboard (the mechanism must be keyboard accessible) or Success Criterion 4.1.2 Name, Role, Value (the mechanism must be exposed to assistive technologies and have an accessible name). This definition, and the rules using it, leaves these extra requirements out. This avoids reporting the same component twice for the same reason (e.g., missing an accessible name) under two different rules and Success Criteria, and helps pinpoint the error related to each Success Criterion. Instruments should nonetheless be fully accessible at the correct conformance level (depending on the rule using them).

Outcome

An outcome is a conclusion that comes from evaluating an ACT Rule on a test subject or one of its constituent test target. An outcome can be one of the three following types:

  • Inapplicable: No part of the test subject matches the applicability
  • Passed: A test target meets all expectations
  • Failed: A test target does not meet all expectations

Note: A rule has one passed or failed outcome for every test target. When there are no test targets the rule has one inapplicable outcome. This means that each test subject will have one or more outcomes.

Note: Implementations using the EARL10-Schema can express the outcome with the outcome property. In addition to passed, failed and inapplicable, EARL 1.0 also defined an incomplete outcome. While this cannot be the outcome of an ACT Rule when applied in its entirety, it often happens that rules are only partially evaluated. For example, when applicability was automated, but the expectations have to be evaluated manually. Such "interim" results can be expressed with the incomplete outcome.

Programmatically Hidden

An HTML element is programmatically hidden if either it has a computed CSS property visibility whose value is not visible; or at least one of the following is true for any of its inclusive ancestors in the flat tree:

  • has a computed CSS property display of none; or
  • has an aria-hidden attribute set to true

Note: Contrary to the other conditions, the visibility CSS property may be reverted by descendants.

Note: The HTML standard suggests setting the CSS display property to none for elements with the hidden attribute. While not required by HTML, all modern browsers follow this suggestion. Because of this the hidden attribute is not used in this definition. In browsers that use this suggestion, overriding the CSS display property can reveal elements with the hidden attribute.

Visible

Content perceivable through sight.

Content is considered visible if making it fully transparent would result in a difference in the pixels rendered for any part of the document that is currently within the viewport or can be brought into the viewport via scrolling.

Content is defined in WCAG.

For more details, see examples of visible.

Useful Links

Implementations

This section is not part of the official rule. It is populated dynamically and not accounted for in the change history or the last modified date. This section will not be included in the rule when it is published on the W3C website.

ToolConsistencyCompleteReport
axe-coreconsistentYesView Report
QualWebpartially-consistentYesView Report

Acknowledgments

Authors

Funding

  • WAI-Tools

Assets

  • JFK's "We Choose the Moon" speech excerpt is courtesy of NASA.
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