Image caption Young people with language impairments can find it difficult to express themselves

Imagine listening to a foreign language you are not familiar with all day. It would be tiring and confusing. You would miss important information and you'd have to work very hard to understand what people were saying.

That's what it's like to have a specific language impairment in your own language, says Gina Conti-Ramsden, professor of child language and learning from the University of Manchester.

"These children aren't mute. They can talk - but it's a hidden disability," she says.

"They can't understand what is said all the time and they find it difficult to put words together, and to express themselves."

Aim of a 'normal life'

Most children with SLIs have quite severe language problems and can spend at least 50% of their education in specialist language units, staffed by specialist teachers and speech therapists, rather than mainstream schools.

The aim is to enable them to go back into mainstream primary or secondary school, and that they can achieve a level of language which allows them to function in society, get a job and lead a normal life as an adult.

There was a lot of mickey-taking from the other kids. And I got frustrated and upset because I couldn't do things. Ross Watson

Prof Conti-Ramsden's current research project is concerned with finding out what happens to such children as adults.

Ross Watson, 25, forms part of her study - the largest of its kind in the UK.

He spent most of his primary education in a speech and language unit, returning to mainstream education in Year 6. He remembers it as a tough time in his life.

"They didn't help much to begin with. There was a lot of mickey-taking from the other kids. And I got frustrated and upset because I couldn't do things.

"I didn't understand why they made me do music lessons when it would have been better to do extra English instead."

In the end, Ross got nine GCSEs, impressing himself and his teachers with a C in French and a D in English.

Finding a voice

But he is honest about how his language impairment has affected him.

He has always found it hard to put sentences together, he finds himself getting edgy in new situations and uncomfortable when he has to communicate with people, particularly face to face.

"Talking on the phone is easier in some ways because I can't see facial expressions, which makes it worse to communicate because I'm always wondering what they're thinking."

Image caption Ross went to Orlando in 2009 to visit the inside of a space shuttle

He says he can't work out when people are being sarcastic, which has led to lots of awkward situations in the past - and he suffers from short-term memory loss.

"I'm still forgetful. I forget to call people back a lot. I have to write it down to remember. And I still find reading hard. I have to use a highlighter pen.

"And in a group situation I don't say things first. I don't like to say anything too early in case I've misunderstood something."

However, Ross has come a long way since he was a "very quiet boy in the classroom" who had trouble finding his voice.

He went on to do a course in mechanical engineering at college and now works as a quality inspector of machine parts. In between he spent six years on an apprenticeship at a major defence company.

But not everyone is as lucky as him.

'Quietly confident'

Afasic, the charity which supports children and parents with speech, language and communication needs, says 6% of children starting school have some degree of speech or language difficulty. Around one in 500 are thought to have a serious long-term problem.

Picking it up early is important, says Alison Huneke, helpline manager at Afasic.

"There's more time to address it if it's picked up at this stage and then the child has less experience of failing and losing ground.

There's more time to address it if it's picked up early and then the child has less experience of failing and losing ground. Alison Huneke, Afasic

"But some schools are good at recognising these problems and some aren't."

In fairness, she says it isn't always easy to recognise a specific language impairment. While in some children it will be obvious, others may need a speech and language assessment first - and it is possible it could be misdiagnosed.

As we grow up language is fundamental to virtually everything we do, says Prof Conti-Ramsden, and problems with it can be linked to issues which develop later in life, like anxiety and depression.

The worst-case scenario is that children with specific language impairments become young offenders, since around half of this group of people are thought to have language problems.

Although young people with SLIs look normal, they can suffer from loneliness, struggle to form close friendships and grow up dependent on their parents. Employment is also hard to secure.

But as an adult it is also possible to focus on the things you enjoy and are good at, much more so than at school.

There are lots of things that Ross still doesn't find easy, such as writing reports, talking on the phone, detecting sarcasm and speaking to his boss, but he believes he acquired an inner strength from his early years of intensive speech and language therapy.

This, he says, makes him quietly confident that he has the skills to compete with the brightest and best in society.