Two features for two different gaps
Captions turn sound into text. Audio description does the opposite kind of job: it turns visual information into speech. A person who is deaf or hard of hearing may miss the words and sounds of a program, while a person who is blind or has low vision may miss what is happening on screen. Each feature fills a different gap, and neither replaces the other.
Audio description is a spoken narration, usually added as a separate audio track, that describes important visual details: actions, settings, costumes, facial expressions that carry meaning, and on-screen text that is not read aloud. It is sometimes called video description or described video, and wording varies by region.
What gets described
Describers decide what a listener needs in order to follow the story. Typical content includes:
- who has entered or left a scene
- physical actions that are not clear from sound alone
- changes of location or time
- visual jokes, reveals and reactions
- titles, signs, credits and other on-screen text
Describers generally aim to say what is seen, in plain and neutral wording, rather than interpret motives or add opinion. The aim is for listeners to form their own impression, much as sighted viewers do.
Fitting description into the soundtrack
Description is normally placed in natural pauses between dialogue so that it does not talk over speech or important sounds. In programs with little silence, there may not be room for everything, and describers must prioritize.
Some material is described with extra time built in. In that approach, the video pauses while the description plays, which gives more room but is only possible in players that support it. The choice depends on the content and the technology available.
How it relates to captions
The two features share a goal, equal understanding of the same content, but they use different channels. A few points show how they relate:
- A program can need both. Some audiences are deafblind or have both vision and hearing differences, and others share a screen with people who need the other feature. For deafblind access, written material that can be read through assistive technology is often important, which is a separate topic from standard captions.
- Captions carry sound information; description carries visual information. Captions can note a door slam or music, as discussed in the article on non-speech information. Description tells the listener who walked through the door.
- They can overlap in places. On-screen text may be both read by a describer and appear in the picture. Good planning avoids repeating the same fact in two forms where it is not needed.
- Neither is a transcript. A combined transcript can bring dialogue, sound cues and visual description into one document. This is sometimes helpful for people who read with refreshable braille or a screen reader.
Different approaches to producing description
Description can be written and recorded by trained people, voiced by a human narrator, or voiced by synthetic speech. Each has trade-offs in cost, naturalness and flexibility. Synthetic voices can be convenient for some material but may sound flat in dramatic content. Whatever the method, the text of the description should be written with care, because poor wording can mislead a listener just as poor captions can mislead a viewer.
Automated tools that describe images exist, and they can make mistakes or miss what matters in a scene. For important material, a qualified human reviewer should check the result.
Planning for description from the start
Description is easier when it is considered during production rather than after. Simple steps help:
- Keep key information in the dialogue where the story allows it, so important facts are not only visual.
- Leave short pauses where natural description could fit.
- Avoid placing crucial on-screen text only briefly or in tiny type.
- Keep scripts and shot lists available for describers.
These ideas fit into the broader practice of accessible production, which looks at text, audio and visuals together.
When description is offered
Availability varies. Some broadcasters, cinemas, streaming services and educational publishers offer description for part of their catalogs, while many videos still have none. Whether description is required for particular content depends on local rules and on the type of organization, so organizations should check with the relevant authority or a qualified professional. Viewers can look in the player’s audio or language menu, or in an accessibility statement, to see whether a description track exists.
Putting it together
For a program that wants to reach as many people as it reasonably can, a good set of features often includes accurate captions, a description track where the visuals carry story or instruction, and a written transcript. Each one addresses a different barrier, and together they make it more likely that a viewer, whatever their senses, gets the same content.