Audio description

Audio description (AD, also audio film description) is an additional audio track or an additional speaker text that makes visual information in a film or video accessible as a description. Audio description describes, for example, locations, people, actions, facial expressions, gestures, overlays, and scene changes if these contents are not clearly present in the original audio.

The goal of audio description is to enable blind and visually impaired people to understand a film's content on an equal basis. The audio film track supplements the original audio instead of replacing it. In practice, a speaker usually provides the description during natural pauses, or the audio description is offered as a separate AD audio track that viewers actively select.

On the web, audio description is particularly relevant for prerecorded videos when the understanding of important visual information depends on visual details. In the WCAG, audio description is anchored as Success Criterion 1.2.5 at conformance level AA. If the audio track already contains all relevant content, an additional AD audio description is not required.

Audio description is a central component of digital accessibility: without an audio film description, information gaps occur because blind and visually impaired viewers cannot grasp locations, people, action, and visual cues. Audio description closes this gap and makes audiovisual content usable for more people.

Equal information uptake: Many film and video contents convey meaning through visual details, such as overlaid text, graphic cues, facial reactions, or nonverbal action. Audio description makes this information audible as an audio film description so that blind and visually impaired viewers can fully understand the content.

Better understanding of complex content: Training videos, product demos, explainer videos, and commercials often work with visual sequences. Without audio description, blind individuals miss crucial intermediate steps, locations, or results. An AD audio track provides the missing description so the content remains comprehensible.

Law and standards: The WCAG define concrete requirements for audio description and alternatives. In Europe, EN 301 549 is established as the reference standard for accessibility in the ICT environment and adopts WCAG criteria such as 1.2.5 on audio description.

Practical relevance: Audio description is established in the audio film environment: a speaker provides a description of people, locations, action, facial expressions, and scene changes. This applies to film, media libraries, streaming, and sometimes even live formats when live audio description is offered.

Which implementation of audio description makes sense depends on how much information is conveyed exclusively visually, how dense the original audio is, and whether there are enough speaking pauses for a speaker's text.

• ✓ Standard audio description (AD in speaking pauses): The most common form. An additional speaker description supplements the audio track during natural pauses. The audio description only describes what is necessary for understanding, for example, locations, people, scene changes, central action, and overlays. This turns a film into an audio film that is accessible to blind viewers.
• ✓ Extended audio description (AD with pauses in the video): If the pauses in the original audio are insufficient, the film is briefly paused at suitable points to make room for additional description. This extended audio description is described in WCAG 1.2.7 at Level AAA. It helps when content is highly visual and the action cannot be understood without additional AD.
• ✓ Media alternative as text: As an alternative, a complete media alternative can be provided that renders all visual and auditory content as text, comparable to a screenplay. This is described in WCAG 1.2.3 as an option alongside audio description and can supplement audio film description if a separate audio track is not available.

Audio description closes a clear access gap: When essential content lies exclusively in the visual plane, it is unavailable to blind individuals without an audio film description. This is exactly what the WCAG requirements for time-based media aim to address.

WCAG relevance: For prerecorded videos, WCAG 1.2.5 (Level AA) applies. Audio description is required when relevant information is not included in the audio. If locations, people, and action are already fully covered by dialogue or speakers in the original audio, no additional AD audio description is necessary.

Legal framework: In Germany, the Accessibility Strengthening Act (BFSG) applies starting June 28, 2025. At the EU level, Directive (EU) 2019/882 forms the basis for uniform requirements, including in the audiovisual media environment. For providers, this means: audio description and appropriate alternatives are part of a robust accessibility strategy.

The WCAG define several success criteria around time-based media that directly relate to audio description, audio films, and audio tracks:

• ✓ WCAG 1.2.3 – Audio Description or Media Alternative (Prerecorded) (Level A): Either an audio description or a media alternative as text must be provided if it is synchronized media.
• ✓ WCAG 1.2.5 – Audio Description (Prerecorded) (Level AA): Audio description must be provided for prerecorded video content in synchronized media if relevant information is not included in the audio.
• ✓ WCAG 1.2.7 – Extended Audio Description (Prerecorded) (Level AAA): If speaking pauses are not sufficient, an extended audio description must be provided, typically with pauses in the film.

For practical implementation in the European context, EN 301 549 is relevant, which translates WCAG criteria into testing procedures and requirements for web, documents, and software.

Manual media check: Check whether your player offers an alternative audio track for audio description (AD) and whether the description covers all relevant content, people, locations, and action. Also test whether viewers can clearly select and deactivate the AD audio track again.

WCAG Mapping: Use the WCAG Understanding pages to look up requirements, examples, and typical errors for each success criterion, especially 1.2.3, 1.2.5, and 1.2.7. This allows you to test audio description systematically against standards.

EN 301 549 Reference: For auditing and proof in Europe, EN 301 549 is relevant as a testing basis since it translates WCAG criteria into testing processes. This is helpful if you need to document accessibility internally or to third parties.