Hello my name is Martin Cornwell and I am a subtitler. As a subtitler, we work on pre-recorded programs, everything from Bargain Hunt to Question Time and also on a lot of live output, such as the BBC news channel.
[re-speaking] Also we have invested in new road project in and around the areas (comma) which have been called for years (full stop)
Most people think subtitlers do a lot of typing, whereas actually we produce subtitles using voice recognition software and a technique that we call re-speaking, where I will have an audio feed of what is coming on through the TV, and I will speak along with that input- repeating it.
[re-speaking] We need to make sure that whatever changes we make have children…
It doesn’t sound much like normal, spoken English. We have to speak in this monotone way, giving equal weight to each syllable we speak.
[re-speaking] So (comma) you know how the game works (full stop) Let’s meet the usual suspects (full stop)
This is because the computer can’t understand a lot of the intonation of normal speech. Today I’m starting off doing a piece of pre-recorded television. It’s a BBC game show, so I’ll have a chance – cos it’s pre-recorded - to speak in all of the subtitles. 
[re-speaking] Behind this screen (comma) our four contestants who will be hoping their knowledge is flawless (comma)…
And then to go back and tidy it all up, correcting any spelling mistakes and making sure it’s 100% grammatically accurate, as well.
This afternoon I’m going to be live on air doing BBC parliament. Where this differs from the pre-recorded stuff is that I have to, before I go on air, research all the words that the computer might not recognise, and teach these to the computer, beforehand.
[re-speaking] Moody’s (comma) Moody’s (comma) the UK has been downgraded by the Moody’s (full stop)
So that when I go live, I should be able to produce some fairly accurate live subtitles.
One of the most important qualities a live subtitler should have really is the ability to concentrate for long periods.
[re-speaking] And for many families involved (comma) the process can be drawn out and emotionally draining (full stop)
We are on air for 15 minutes at a time, so it’ll be 15 minutes on, 15 minutes off, but that could be over the course of two and a half hours. So you need to be able to maintain your concentration the whole time, making sure you’re hearing everything that have being said, by ALL of the speakers, and recreating it, accurately.
It is very satisfying to think that we’re helping people that are hard of hearing to enjoy TV in the way that that they might not have done in the past. Obviously, they have a right to expect a very high standard and when we can provide that, it feels good.