A growing number of countries and States are requiring that audio-visual materials are made accessible to visually or hearing impaired audiences. Indeed, unless some steps are taken to compensate for their limited access, these audiences will miss out on a large part of the audio-visual content.
For visually impaired audiences, the solution is audio-description, also called descriptive audio or descriptive video.
For hearing impaired audiences, the solutions are captions, closed-captions or transcripts, or sign-language interpreting.
Each of these techniques has various advantages and inconvenient and some of them are legally required for some or all publicly accessible audio-visual material, depending on the location.
First, let’s examine what are each of these technique enabling accessibility to visually or hearing impaired audiences.
Audio-description (AKA descriptive audio or descriptive video)
Audio-descriptions are supplementary audio tracks where a narrator describes or contextualizes critical visual information that would be missed out by visually impaired audiences. The audio-description narrator inserts the description during natural pauses in the audio track, or even during the dialogues when the action on screen justifies it.
Audio-description come in 3 formats
- Closed Audio-Description (or Closed Caption Audio-Description)
This requires the audience to take the required action to activate the audio-description. Unless the audio-description is turned on, the audio-visual material will be viewed without it.
- Open Audio-Description (or Open Caption Audio-Description)
This means the audio-description will be broadcasted to all audience, without the option of turning it off.
- Real-Time Audio-Description (or Real-Time Caption Audio-Description)
These are live commentary on live events, such as conferences, theatrical productions or other. The trained audio-describer will narrate the description of the event to headphones provided to the visually impaired audience.
You can access all relevant information on how to train to become an audio-describer on the American Council for the Blind website
Captions, transcripts, or sign-language interpreting
- Captions are on-screen texts that transcribe the characters’ dialogue, identify the speakers and describe sounds otherwise inaccessible to hearing-impaired audiences. These captions are synchronized with the video image, enabling viewers to access a close equivalent to the soundtrack. Captions are increasingly relied on by non-hearing impaired audiences to watch audio-visual content in situations where it would be inappropriate to access the soundtrack. As such, they are becoming increasingly ubiquitous, regardless of the legal requirements to add them to audio-visual material.
There are two types of captions:
- Closed Captions: To access closed captions, the viewer is required to physically activate them by clicking on the relevant button or pre-setting a TV or other viewing device to display closed-captions by default.
- Open Captions: those are displayed by default to all viewers and cannot be turned off.
- Transcripts are a transcription of the monologue, dialogue or multi-speaker discussion taking place in the audio-visual material being transcribed, with or without mention of additional intervening sounds. Though transcription software are becoming increasingly accurate, to date, a clean transcript still requires considerable human editing in order to be intelligible.
There are 2 types of transcripts:
- Indexed Transcripts: These are transcript containing discrete units of time matching the spoken audio occurring during that time. These can be used to generate captions, open or closed.
- Non-Indexed Transcripts: These are transcripts of the spoken words transcribed without time reference and are typically provided as an addendum to the audio-visual support, whether displayed below or next to the video, or offered as a separate document.
- Sign-Language Interpreting on audio-visual support relies on the skills of a sign-language interpreter that translates the spoken words into sign-language and is embedded in the video stream, typically in a circular, ovoid or square “window” at a bottom corner of the screen.
These are all the accessibility enhancements for audio-visual material currently available and some or all of them are legally required on some or all publicly available audio-visual material. In our next post, we will have a cursory look at which accessibility legal requirements apply to different regions, States and countries.