caption quality and timing

To the RQTF

Following on from the action to look at timed media, I've made contact with an expert in the area of captions and he provided me with a link to his report.

Below is  the section of the  report related to caption timing. The full report can be found at https://mediaaccess.org.au/research-policy/white-papers/caption-quality-international-approaches-to-standards-and-measurement

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7.2 Time lag in live captions (latency)
The delay between the speech (or other sounds) and the corresponding captions appearing on the screen in a program which has been captioned live is one of the most often voiced caption complaints made by Deaf and hearing impaired TV viewers. In a 2013 survey conducted by Action on Hearing Loss in the UK , it was considered to be the biggest problem by the greatest number of respondents (24 per cent), with the next most serious problem being inaccurate captions (22 per cent).

The time lag in live captions is determined by several factors, including the production systems in place, the reaction time of the stenocaptioners and respeakers, and the complexity of the dialogue. Ofcom's code sets a target of 3 seconds, which is often considered the shortest time lag that can be reasonably expected in most circumstances. This may change, however, when the results of Ofcom's two-year caption quality measurement exercise are in.

The Canadian English-language and French-language caption standards allow for a longer time lag (6 and 5 seconds respectively). The French charter calls for a lag of less than 10 seconds (which most caption users will find frustratingly long), reflecting a greater emphasis on ensuring that spelling and punctuation are correct.

It should be noted that there is ambiguity in all of these standards, as none of them make it clear whether the maximum time lag target applies to individual captions or the average over the whole program. Ofcom appears to be thinking about this issue, as in its measurement exercise, it has asked broadcasters to measure both the average latency and range of latencies.
The time lag in live captions is such a crucial factor for consumers that we feel that all caption quality standard should acknowledge this. We believe that 5 seconds is appropriate as a target which is achievable in most cases. It should be made clear that this target applies to the average time lag over the length of the program.

To overcome the problem of delay in live captions, it is often suggested that the broadcast of programs be delayed to allow time for the creation of the captions. This idea has generally been resisted by broadcasters, although it has been adopted by the Flemish public broadcaster VRT in Belgium, which delays its live programs by up to 10 minutes. And, as noted above, Ofcom will continue to discuss the idea with UK broadcasters.


  The DCNP has provided a useful summary of this research which is available at: http://www.captioningkey.com/captioning_presentation_research.pdf
  http://www.dcmp.org/caai/nadh131.pdf
  http://www.actiononhearingloss.org.uk/

[Scott Hollier logo]Dr Scott Hollier
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