And now I've found something - an article - from Joel Snyder:
"To a great extent, audio description can be considered a kind of literary art form in
itself, a type of poetry. It provides a verbal version of the visual whereby the visual
is made verbal, aural, and oral. This is normally done using words that are succinct,
vivid, and imaginative in order to convey the visual image that is not fully accessible
to a segment of the population (i.e. the blind and the partially sighted) and
may not be fully realised by the rest of us, who can see but may not observe."
"All people need to be full participants in their nation’s cultural life. It must be
remembered that the ‘able bodied’ are only temporarily so: there is only a thin
line between ability and disability. With a focus on people’s abilities, we will come
much closer to greater inclusion and total access."