Leah is as good as gold. The conscientious five-year-old quietly gets on with her work, always completes her homework and is never disruptive at her large primary school. So nobody really noticed she had not spoken to her teacher that day. Only when she had not uttered a single word for the best part of a year, did teachers realise this was more than just acute shyness.

Leah is one of a growing number of young people who do not, and cannot, speak at school. It is estimated that seven in 1,000 children suffer from selective mutism, a crippling phobia that prevents children from talking to certain people in certain environments, even if they want to.

“More children are finding school frightening and becoming selectively mute because they are typically starting school much younger,” says Alice Sluckin, chairwoman of the Selective Mutism Information and Research Association (SMIRA) and a former psychiatric social worker. “Very young children can be vulnerable and find it harder to cope in school, especially now there is more stress on talking and participating than there used to be.”

Other possible causes include an increasing emphasis on targets in the early years of education, and the popularity of passive, non-verbal pastimes such as TV and video games. Although selective mutism is becoming more prevalent, knowledge about it still remains sketchy, even among professionals.

In 1994, the term “elective” was replaced with “selective”, in an attempt to clear up a widespread misconception that these children choose to be silent. There is also a misguided belief that selectively mute pupils are being deliberately stubborn, rude, manipulative or difficult. The reality is very different. Like stage-struck actors, most of the youngsters want to speak but their fear prevents them from doing so.

“The children are controlling their own anxiety by keeping quiet, not trying to take control of other people,” says Maggie Johnson, a speech and language specialist and author of The Selective Mutism Resource Manual. “It is a form of social anxiety linked to fear of others hearing their voice and hyper-sensitivity to others’ reactions.”

Six-year-old Jack was almost paralysed with fear when he had to speak to children in his Yorkshire reception class. His knees would shake, his face would go bright red and he would swallow hard to try to dislodge the growing lump in his throat. Although his parents knew he was an anxious boy who deeply distrusted change, much of his reluctance to speak was masked by his willingness to talk freely with his twin sister and immediate family at home.

“He is perfectly chatty in the house, but he’s like another child at school,” says Hilary, his mother. “He can barely even whisper to his sister or me when he’s there and he certainly won’t interact or play with other children. For him, school is a scary place.”

Jack is not a wholly typical example. Most selective mutes are less likely to speak to adults than children and are also more likely to be female or from an ethnic minority background. Occasionally, older children who have been bullied or publicly humiliated become selectively mute, but usually it starts from when they go to school or begin to mix with people beyond the family.

Bethany Hampton’s problems began when she went to nursery. For the next three years or so, she would not speak to teachers. Now in Year 3, she whispers her answers or communicates with a friend, who in turn tells the teacher.

Bethany, below right, is hugely expressive through her eyes, face and body.

Kevin, her father, puts her progress down to the patience and dedication of her teachers at Christ Church First School in Frome, Somerset.

The first time Anne Steel, a Year 2 teacher at Christ Church, heard Bethany’s voice at a normal level was when she telephoned her home and the girl answered. “It was incredible,” says Anne. The teacher instinctively used humour to help Bethany relax in class and made sure she never put her under any pressure to talk. But she received little or no external help.

Teachers and parents across the country report similar experiences. Hilary says SM is still shrouded in mystery, just as dyslexia was 30 years ago.

“The school has been great, but all the initiatives to help Jack came from me, not any experts,” she says. “Speech and language therapists say it’s not in their realm of expertise, while educational psychologists are busy with the disruptive children. I feel sorry for kids who don’t have pushy parents like me.”

Dr Rosie Sage, senior lecturer at Leicester University and the author of Silent Children, believes teacher training is essential if pupils and their parents are to start feeling more supported. “Trainee teachers must be taught about child development, not just how to get pupils through the national curriculum,” she says. “You can’t spot or help these children unless you have some understanding about how young people express themselves. Some don’t get spotted until secondary school.”

There were two SM children from the same family at Sandwich Infant School in Kent. “They were a quiet family, so I put it down to the children just being shy,” explains Mary Kobylecki, the special needs co-ordinator.

Sophie, the elder of the two and the worst affected, could not speak to her teachers, although she could read aloud. She began by writing down her answers in class, but after some time she could give yes or no answers.

Eventually, she was able to answer using short sentences. “Our aim was to make sure Sophie could ask basic questions at her next school, such as, ‘Can I go to the toilet?’” says Mary. The school was lucky enough to receive expert help from Maggie Johnson.

One of the strategies she used was to play and talk through games with Sophie at home, where she felt more comfortable.

Then they would play the same games at school, with a classroom assistant standing at the door. After six weeks, and with the permission of Sophie at every stage, the assistant finally sat down and played with them.

“It took three years of hard work,” says Mary, “but we got there. You can’t rush it, otherwise you go back to square one”

For more information about the condition contact SMIRA on 0116 212 7411 or email smiraleicester@hotmail.com

Tell-tale signs

Pupils who have not spoken for more than a month in a new environment (excluding the first settling-in month) can be described as having selective mutism.

Selective mutes may speak to some people (peers) but not others (adults).

Some may speak in one location (the playground) but not in another (the classroom).

SM is not just shyness. It is a psychological problem where children freeze and are unable to speak even if they want to.

What to do

Tell them that you understand how difficult it is for them to speak.

Take the pressure off them to talk and find other ways in which they can participate. For example, pupils can demonstrate their reading ability by matching sentences to the appropriate picture or even by recording themselves reading to parents before playing the tape at school. They can express themselves by holding up answers or through pointing to a communication chart.

Reassure the pupil that they will be able to talk once they feel more comfortable and relaxed, and that they can take it just one step at a time.

Explain to classmates that the non-speaking pupil is not being rude or unfriendly and enlist their support so the child is not isolated.

Allow the pupil to sit with and talk through their best friends, so they gradually get used to using their voice in class without anxiety.

Be vigilant, the pupil may not be able to ask for help when they need it.

Horror that can make you mute

Traumatic mutism is different from selective mutism and involves a person not speaking as a result of a highly traumatic event.

Maya Angelou, author of I Know Why the Caged Bird Sings, was eight when she revealed her mother’s boyfriend had sexually abused her. Her uncles beat the man to death.

Horrified that “the power of my words led to someone’s death”, Maya became mute and did not speak at all for five years.

Many First World War soldiers also lost their voices after witnessing the horror of the trenches.