Lipreading Myth 1: Lipreaders can do it

A number of times a year I receive e-mails asking me for the name of a lipreading expert. In one case, someone had recorded video at a wedding, all guests had said something .... yes, and that was the problem: what did the guests say? The sound was very bad, and no-one could hear what the guests said. So can I please caption the video for them?

No.

There's a YouTube video of the new pope meeting the Belgian king and queen. Some Royalty TV programme mailed me: can I please tell them what the Belgian king said to the pope? There was no sound, they weren't even sure what language was being spoken. Please send us the text before tonight's progamme.

Sorry, can't do.

Someone involved in a lawsuit. They had video of the suspects, shot from far away. Can I please tell them what the suspects were saying? 

No.

I know that - in the UK and the USA - there are specially trained 'forensic' lipreaders. For more info about this, see Wikipedia: 
http://en.wikipedia.org/wiki/Forensic_speechreading

But really, it is a myth that an expert lipreader can tell you what is being said by a speaker on video. There is too much uncertainty. 

To be able to lipread what someone says, you have to be familiar with 1. the language, 2. the speaker, 3. the topic, and 4. the context. The face and mouth-movements of the speaker have to be very clearly visible. And even then, an expert lipreader will not be able to tell you with 100% certainty what was said.

Recognition, or matching, on the other hand, is quite easy. Once you know what a person says, you can recognize the visual patterns and check whether what you see matches the words that you are expecting. 

That's probably why many hearing people think that lipreading is easy: "Oh, yes! Of course, now I can see what the pope / suspect says!"

In many cases, however, many different words / phrases will match what you see. 

For funny examples, watch the Bad Lip-Reading videos on Youtube

http://www.youtube.com/user/BadLipReading 

"I'm proud to say yo' mama took a Cosby sweater"

This particular video of Obama's inauguration:
http://www.youtube.com/watch?v=fpwhA-LdOHo&feature=c4-overview-vl&list=PLF396D3CEF0169A35