Link live statements to their prepared script
When a live broadcast follows a script written in advance, that script is already a more accurate record than anyone could type in real time. G151 says link to it from the page carrying the audio, either elsewhere on the same page or at another address, and the linked text should itself conform. What it cannot do is stay in step. The script is not synchronized with the audio. W3C is explicit that the technique only holds while the speaker sticks to it, and that is where it usually breaks in practice. W3C lists this as sufficient for 1.2.9 Audio-only (Live), at Level AAA, so it belongs to the live audio-only rule rather than to the Level A rule about prerecorded media.
How we find it in an audit
Our reviewers look for the link first, on the page with the stream, worded so a reader knows where it goes. Then we compare a sample of the script against the audio. Any stretch where the speaker took questions or ad-libbed is a stretch the script no longer covers. Something else has to.
How affected users experience it
A deaf viewer watching a statement with no text has the picture and no content. Linking the prepared script gives them the words at the same moment everyone else hears them, which is the difference between attending and being told about it later. The unscripted question session afterwards is the part that still leaves them out, and it is the part sites most often forget.
Passes vs. fails
Passes
Beside the stream sits 'Read the full statement (text version)', linking to the script the speaker is following.
Fails
A CEO reads a prepared statement on a live audio stream, and the text exists internally with nothing on the page linking to it.
Other ways to satisfy this rule
3 guides on this site are filed under 1.2.9 Audio-only (Live). W3C lists this one as sufficient for that rule on its own. Implement it correctly, in a way your readers' software actually supports, and the rule is met.
This guide is our interpretation of W3C technique G151: Providing a link to a text transcript of a prepared statement or script if the script is followed. W3C publishes its techniques as guidance rather than as the standard, and says so on every one of them. The success criterion is what conformance is measured against, and a technique is one documented way to meet it.