Audio Description

WCAG 1.0 Under "Equivalent" One example of a non-text equivalent is an auditory description of the key visual elements of a presentation. The description is either a prerecorded human voice or a synthesized voice (recorded or generated on the fly). The auditory description is synchronized with the audio track of the presentation, usually during natural pauses in the audio track. Auditory descriptions include information about actions, body language, graphics, and scene changes.

WCAG 2.0 audio description Audio narration that is added to the soundtrack to explain important details that cannot be understood from the main soundtrack alone. During pauses in dialog, audio descriptions of video provide information about actions, characters, scene changes and on-screen text to people who are blind or visually impaired.

<geoff> As I mentioned on the 11/29 call, NCAM's "Accessible Digital Media" guidelines (http://ncam.wgbh.org/publications/adm) contain a few brief pointers about writing descriptions. I've pasted them below; the direct URL is http://ncam.wgbh.org/publications/adm/appendix.html#app5 . Note that these are aimed at multimedia presentations, not static images.

Appendix 5: General Audio Description Guidelines

No general guidelines are publicly available for writing audio descriptions. The information below relates specifically to audio descriptions written for the Access to PIVoT project (http://ncam.wgbh.org/webaccess/pivot/) and is presented as an example of how description writing was approached for on-line physics lectures and tutorials. It is not intended to be a complete tutorial on writing audio descriptions.

1. Watch the entire presentation before writing any audio descriptions. This will help you determine where descriptions are necessary, how much information must be added to the original presentation, and if extended descriptions will be necessary.

2. You will also find it helpful to watch the presentation with the monitor turned off, or with your eyes closed, listening carefully to the audio. If you can't understand something the speaker is talking about, neither will a blind or visually impaired student.

3. Identify the points in the presentation that need audio descriptions. If the speaker speaks aloud what he is writing on the board, or if he sufficiently describes a picture he has drawn, an audio description may not be necessary. However, if he fails to speak written information fully or describe a drawing completely, or if he makes a reference to location (e.g., "up here," "over there," "look at this," etc.), you must supply a description.

4. When writing descriptions, first determine if the additional information can be written to fit within an appropriate natural pause in the program's sound track. If no such pause exists, you must insert an extended description at that point. Extended descriptions may be of any length, but keep them as concise as possible while still conveying all necessary information. You may find it helpful to first write a full description and then edit it to an appropriate length, rather than writing and editing simultaneously.

5. Use vocabulary appropriate to the subject matter and to the audience.

6. When writing descriptions for a young audience, use age-appropriate descriptive language. Include complex concepts or vocabulary several times, within context, throughout the description. Write in short sentences for better comprehension.

7. Insert each description, extended or not, at a natural point in the movie's timeline. Don't cut off the speaker in mid-word; instead, take advantage of any brief pause. Even a pause between words or sentences will suffice as long as the description is not out of context at its insertion point. You may "predescribe" (that is, insert the description slightly before the action occurs on screen) if it clarifies the situation.

8. Use a specialized descriptive language, such as MathSpeak (http://www.rit.edu/~easi/easisem/talkmath.htm), for scientific and mathematical expressions.

9. Use MAGpie (http://ncam.wgbh.org/webaccess/magpie/), a free application available from NCAM, to write, edit, time and record descriptions for digital video. Be sure to record the descriptions in a quiet room, speaking naturally and clearly into the microphone.

</geoff>