Marking Unintelligible Speech in Captions
Marking Unintelligible Speech in Captions records a distinct W3C-supported caption-writing task while keeping implementation mechanics and unsupported house-style rules outside the guidance.
When speech cannot be understood, W3C WAI recommends marking it as “[unintelligible]” rather than inventing words.
Key details
Important caveats
Scope Boundary
Use the marker only when the speech genuinely cannot be understood; do not substitute it for careful listening or routine editing.
Further guidance
Content
Use a clear unintelligible marker when the audio cannot be transcribed reliably.
Practical Application
When speech remains impossible to understand after reasonable review, mark the uncertainty with “[unintelligible]” rather than guessing or inventing words. Use the marker only for genuinely undecipherable speech.
Purpose
The marker tells users that speech occurred but could not be understood, preserving uncertainty instead of fabricating content.
Reader Check
Have you made a reasonable attempt to understand the audio, and if it still cannot be transcribed reliably, does the caption preserve that uncertainty explicitly?
Worked Example
Caption “We met at [unintelligible] before sunrise” when the location cannot be heard clearly, rather than supplying a guessed place name that the audio does not support.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- Transcribing Audio to Text — W3C WAI (opens in a new tab)World Wide Web Consortium (W3C) Web Accessibility Initiative · W3C WAI guidance for identifying speakers and representing relevant audio information in transcripts and captions.