The Guardian

London:

Scientists trying to unravel the workings of the human brain have discovered for the first time how it plucks speech from other noises, breaks it down and works out more than just the meaning of the words.

What has stumped researchers over the years is how we are so good at language and are able to convey and perceive information not just using words, but with more subtle devices such as intonation and rhythm. “There’s nothing else like human speech in nature. As well as the information carried by the words, you can tell someone’s mood, their gender, their age and where they may come from. It’s amazing,” said Sophie Scott, an expert in speech neurobiology at University College London (UCL).

Among the big guns rolled out by researchers to crack the mystery of human language is the brain scanning technique, functional magnetic resonance imaging (fMRI). Able to take snapshots of brain activity, fMRI gives an unprecedented insight into the inner workings of the brain. Using fMRI Dr Scott has shown that the brain takes speech and separates it into words and “melody” — the varying intonation in speech that reveals mood, gender and so on. Her studies suggest words are then shunted over to the left temporal lobe for processing, while the melody is channelled to the right side of the brain, a region more stimulated by music.

Brain imaging has also thrown light on one of the longest standing puzzles of speech — what it is about language that makes us prick up our ears and concentrate on listening. “Like other sounds, speech is just airwaves vibrating. But somehow we cannot ignore speech like background noise. We perceive it almost obligatorily,” said Ingrid Johnsrude at Cambridge University, England.

Dr Johnsrude’s team investigated by playing speech sounds and similar sounding non-speech sounds to people in an fMRI scanner and looked to see which part of the brain was kicked

into action by speech. They found that speech was singled out for special treatment near the primary auditory cortex. The Cambridge team is also investigating how our brains wrestle with a quirk of English — that about 80 per cent of words have more than one meaning.

“Language is at the very heart of what makes us human,’’ said Geoffrey Crossick, chief executive of the Arts and Humanities Research Board. “It is about how we think, understand the world and communicate with each other. If we are to understand these activities, let alone to harness technology to help us carry them out, it is essential that we understand language and how it works.”

Teasing out the secrets of the brain and how it processes language is more than just an academic endeavour. “The more we can understand about how the normal brain is operating the more we can start to understand what happens when things go wrong,’’ said Dr Scott. For example, strokes often affect people’s ability to speak or perceive language. But damage to different regions can have wildly different effects. Stroke damage to the right side of the brain could leave a person unable to pick up on the emotion conveyed in someone’s voice, whereas damage to the left could leave them struggling to understand certain words.

By getting a handle on how language is processed in the healthy brain, scientists hope to develop better rehabilitation therapies which, combined with drugs, can help retrain people’s brains, helping them remaster the unique human ability of language.

The language of e-mails is also under intense scrutiny from researchers Jon Oberlander, the Edinburgh University scientist running the research, has developed a “style checker” that can be used to check e-mails before they are sent out. Another research thrust is aimed at getting computers to understand language, which could revolutionise information gathering, something of acute interest to the military, business and in medicine. Rob Gaizauskas at Sheffield University, England, is developing computer programmes that understand language so well they can trawl through documents and compile reports on particular issues. The technique could be used to monitor electronic news services for activity by terrorist groups, the goings-on at particular companies, or, in a case he is working on now, sort through volumes of medical files to gather information on patients. The system can also be used to trawl the Internet and check student or government reports for plagiarism.