What do your facial expressions give away about you?

New technology is claimed to be able to figure out if you're happy or sad, bored or enthralled - and is offering companies the chance to find out how you react to their online advertising.

Biometric tracking uses a standard webcam to map the facial expressions of people who have given their permission to be monitored.

The technology is currently being used to map how volunteers react to big budget advertising campaigns before they are launched.

The BBC conducted an informal experiment with developer Realeyes for Radio 4's consumer programme You & Yours.

The experiment measured the emotions of 150 Radio 4 listeners, charting every grin or grimace as they listened to some of the station's better-known tunes.

They were the theme from The Archers and the gentle Sailing By, which was made famous by the Shipping Forecast.

The themes were up against God Save The Queen to see how they would compare.

When it came to generating happiness, the Archers theme made 90% of those tested happy, the software said, ahead of Sailing By on 89%, and the National Anthem trailing at 83%.

Mihkel Jäätma, managing director of Realeyes, said: "The computer programme is able to see how the eyebrows, mouth and eyes move around.

"There's a set of six universal emotions which are the same for everyone. It doesn't matter where they come from or how old they are. This is what we have trained our computers to be able to read from people's faces.

"We are hoping that the technology will allow advertising in the future to be more relevant, less annoying and less pushy."

The data showed that both the Archers theme and Sailing By created the most happiness at the beginning as people started to recognise the music.

Other expressions that were assessed included confusion, anger, surprise and disgust.

While the happiness rating for the Archers theme grew as the tune continued, Sailing By's remained stable throughout.

The 150 volunteers' reactions suggested there were two peaks of happiness during God Save The Queen, the first just after the drum roll that heralds its start, and the second at the lyrics "send her victorious".

After that, however, the happiness readings tailed off and evidence of boredom increased.

Oliver Banham-Godfrey, Realeyes' head of operations, analysed the data.

"The Archers performs well across several different categories," he said. "So it would be a very high-performing ad in our database."

Hedli Niklaus runs Archers Addicts, the official fan club, and plays Kathy Perks in the show.

She said: "Billy Connolly said Barwick Green [the theme] should be the National Anthem.

"We have so many who remember listening to it when they were children, we have expats and we have a lot of truckers who listen.

"The dum-di-dum-di-dum-di-dum has a ring to it and they instantly recognise it."

Mr Jäätma said there was more potential for the technology than just advertising, and that it could be used in the same way computer cookies are today.

He said: "People are going to get a lot of benefits from a computer which understands how they feel.

"Imagine if a website knew I was unhappy because I couldn't find what I was looking for?

"This type of data collection will be part of a bigger online experience."