Web Accessibility Criteria- Audio Descriptions


Audio Descriptions are narrations of on-screen movement and visuals portrayed in a video. They are intended to allow users with visual impairments to better understand the context of a video. There are three types of audio descriptions:

  1. Closed audio description: Users can turn the audio descriptions on or off.
  2. Open audio description: The audio description is played automatically, and users are unable to turn the audio description off.
  3. Real-time audio description: A trained audio describer provides live commentary or narration — a real-time audio description commonly found in live theater and live events.

When it comes to accessibility, audio descriptions are required for all prerecorded and live media if the media contains visuals and elements that are not explained by the narrator in the video. 

Why are Audio Descriptions Important? 

Audio descriptions allow users who are unable to capture the visual content, understand this information. Users who benefit from audio descriptions include: 

  • Users that are blind or have low vision 
  • Users that have cognitive disabilities
  • Users who are non-native speakers
  • Users who are visual learners

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 Best Practices

  • Audio descriptions must be provided for all media with visual content that is not explained by the narrator in the video.
  • Audio descriptions must be clear and must only depict what is occurring on the screen without interpretation or comments. 
  • When audio descriptions are provided, the narration should not overlap the audio of the original video.
  • Time management when developing audio descriptions is critical. It takes time to generate media files and adding the audio descriptions during development will streamline the process.
  • When using YouTube, best practice is to upload two versions of a video, one with audio descriptions and one with the default audio. Both videos must be captioned. 
  • Visual presentations with no audio do not require an audio description. Rather, they require text transcripts to translate all the visual elements present. 

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Example 1: Lion King Audio Description 

The example below is a video demonstrating descriptive audio descriptions. This video is a portion of Disney's the Lion King with audio descriptions describing the first few minutes of the film.

(Derived from: YouTube- Descriptive Video demo on The Lion King)

Example 2: Frozen film trailer with audio description

The example below is a video with audio description. The audio describer announces the movement of characters, their facial expressions and any on-screen action occurring in the video. 

(Derived from: YouTube- Frozen Trailer with Audio Description)


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 Testing Methods 

  1. Visually review if the transcripts, captions or audio descriptions have the correct text and in sync with the media.
  2.  Inspect multimedia content to determine if pause, stop and play controls are incorporated within the file. 
  3. Verify if embedded content is accessible to all users including assistive technology users. If the content is not accessible, it is recommended to use different embedding methods or multimedia file types. However, if no other alternative is possible, the <noembed> tag must be incorporated. 

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 WCAG 2.1 and References