How captions and audio description make media usable

Captions and audio description are different tools that solve different problems. Captions turn sound into text on screen. Audio description turns important visuals into spoken words fitted between lines of dialogue. Together they decide whether a programme is usable by someone who cannot hear it well or cannot see it clearly.

Captions and subtitles are not the same thing

Subtitles usually translate dialogue into another language. Captions cover the dialogue too, but they also carry the sound information a viewer needs: a door slamming, music starting, a speaker who is off screen. Captions come in two forms. Closed captions can be switched on and off by the viewer; open captions are burned into the picture and are always visible.

What audio description adds

Audio description narrates what the dialogue does not: a character entering, a physical action, on-screen text, a change of scene. It fits into the gaps between speech, which is why it is planned early. Description written into the script before filming has natural pauses to sit in. Description added afterwards has to squeeze into whatever silence the edit left behind.

What the standards require

The Web Content Accessibility Guidelines, the international benchmark for digital accessibility, treat captions for recorded audio and description of visual information for recorded video as baseline requirements rather than extras. The W3C's media guidance breaks that down into components: captions, transcripts, description, sign language where the audience needs it, and a media player that supports them all.

Who actually uses these features

Captions are read in noisy rooms, on muted phones, and by viewers following along in a second language. Description helps anyone whose view of the screen is limited. Transcripts are searchable, quotable and easy to translate. These features are not a narrow concession to one group of viewers.

How to find and tune them

• Look for a subtitle or CC button on the player, and check the audio menu for a described version of the track.
• Change size, font and background where the player allows it. Captions over a busy image are hard to read at default settings.
• Report captions that lag behind the speech or miss sound cues, because both are usually fixable.

Production guidance from the Web Accessibility Initiative at w3.org and the WCAG standard at w3.org cover how each element should be made, and the bbc.co.uk accessibility pages show how a broadcaster explains the same settings to its own audience.

The bottom line: treat captions and audio description as part of the programme rather than an optional add-on, and switch them on before deciding a title is unusable.