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Adapting Video for VI Learners

Extending existing video materials

Audio Subtitling

What Audio Subtitling is and when it is useful

Audio subtitling (or Audio Description) is like a Greek Chorus. A narrator uses any gaps in the main action dialogue to describe what is going on. The narrator is chosen so that his or her voice is easily distinguishable from the actors, commentators, or narrators in the video itself.

Frame from training video(D)

View video without (6.4 M) and with (6.3 M) Audio Description

Audio subtitling is of most use to blind video audiences, although the cues given can help less visually impaired viewers too. Since its increasing success in American public service broadcasting, the technique has spread beyond video and TV. For example, audio subtitlers are being employed in theatre productions, using a closed loop audio transmission system like those set up for hard-of-hearing audiences.

How it works

Like text subtitles, audio subtitling on linear formats like VHS comes in two flavours - open and closed.

  • Open audio subtitles are mixed into the overall soundtrack. Once there, the whole audience has to listen to both action and commentary.
  • Closed subtitles are carried on a separate track, and can be switched off when not needed. So a video for general consumption can have a closed track which a VI learner can use for private listening.
  • Non-linear and digital formats are much more flexible.

    What you need to add audio subtitles

    If you have access to editing suites, so much the better. Synchronisation and merging of your new material with the old will be much easier.

    The most important need is for a good script. Creating one is a non-trivial problem, and you will need all the advice you can get. We have an introductory checklist, but we urge you to read more before you start. The Audio Subtitlers have been refining their art for a while now, and if your computer is linked to the Internet then a helpful Web site is The Audio Description Home Page. The RNIB also have good advice to offer, and we have links to these and other resources in the Refernces section.