Lose your voice and you could lose your job. Every year, many teachers are forced to quit the profession after finding out the hard way that a healthy voice is the most essential tool of the teacher’s trade. Many more take regular sick leave as they struggle with severe vocal disorders.

There are no official statistics for the number of teachers who suffer voice problems. But the speech therapy department of a Stoke-on-Trent hospital recently reported treating 83 teachers over an 11-month period, so the figure may run to several thousand a year. What makes teachers so susceptible?

Having to speak for hours on end, day after day, is only part of the problem. A healthy voice will thrive on hard work - if it is used correctly. But most teachers receive no professional guidance on voice care, and only a small minority of training courses offer even basic instruction. “A simple understanding of how the voice works could prevent more than half the problems we see,” says Roz Comins of the Voice Care Network. She established the network in 1993 specifically to help teachers after discovering that they accounted for one in three referrals to speech therapists. The organisation offers advice and arranges nationwide workshops and voice tuition.

At Leechpool Lane primary school in Horsham, West Sussex, headteacher Anne Webber arranged a VCN workshop after losing one member of staff for long periods because of voice difficulties. “I wanted to prevent similar problems - and I thought this was important for the whole staff, including the playground supervisors and catering team. They all find themselves having to speak above noise.”

The workshop consists of a general introduction, followed by exercises on breathing, resonance and extending the vocal range. As Ms Comins points out, staying healthy is not the only benefit of learning to take the strain off your voice - it also greatly enhances your communication skills. A relaxed, well-produced voice has more “colour” than one that is forced or pushed.

“Teachers often resort to speaking loudly to hold attention. But once you learn to use the full range of your voice, you will be amazed at how easy it is to engage your audience,” she says.

According to Anne Webber, the response at Leechpool was “overwhelmingly positive”. She now intends to book regular “refresher” workshops for the whole staff, and has arranged for teachers with specific problems to receive one-to-one tuition.

Ms Comins says the voice is “an individual matter. There is so much to go wrong - it is likely to be a combination of factors. Speech involves the whole body, not just the mouth and throat.”

In simple terms, speech is produced when breath passes over your vocal cords, causing them to vibrate. The sound is amplified by the resonating cavities in your chest, mouth and head. Finally, your lips, tongue and teeth shape the stream of sound into recognisable words.

The two main impediments to this process are tension and poor breathing. When we breathe properly we use our abdominal muscles. If we take only shallow breaths, the weaker chest and neck muscles have to do the work, putting tension and pressure on your vocal cords.

It is partly because tension and poor breathing are endemic among teachers - a result of the emotional stress which goes with the job - that voice problems are so common. And tension stems not only from hunched shoulders or gritted teeth. Ms Comins remembers one teacher who suffered because she spoke through a permanent smile in an attempt to please her young audience.

Taking deeper breaths, and finding time to roll your shoulders gently and massage the sides of your neck, should release tension. And correct posture will help by ensuring a clear flow of breath from your lungs to your larynx. But if these adjustments have no effect, it is worth thinking about whether your classroom environment is to blame.

Poor acoustics can make you feel that you need to speak more loudly, as can background noise from another classroom. A dry and stuffy atmosphere will also cause problems. One teacher tells how he suffered regularly from sore throats and hoarseness while working in a modern, air-conditioned classroom. His symptoms vanished within a few weeks of moving to a draughty Edwardian building.

You may be able to overcome bad acoustics by rearranging your classroom - and sipping water throughout the day will combat the effects of an overactive heating system. But if you believe your working environment has an adverse effect on your voice, raise it as a health and safety issue. The unions say voice problems are a “foreseeable risk”, and employers could be liable for compensation if they fail to address poor conditions.

Above all, recognise the early symptoms of vocal abuse - which include hoarseness, pain when swallowing and increased mucus production. In these circumstances the best cure is complete rest. Piano players are protective of their fingers, and footballers insure their legs for millions, but teachers, it seems, have less regard for the main tool of their trade. “If it is painful to speak, that is nature’s way of telling you not to,” insists Roz Comins.

Kate Leary, a chemistry teacher at Wombwell high school, south Yorkshire, developed nodules on her vocal cords - a sign of long-term wear and tear. She had surgery to remove them and was told she might face recurring problems for the rest of her working life.

But new technology means vocal injury does not have to signal an end to a classroom career. Ms Leary now uses a clip-on radio microphone and amplifier to take the strain from her voice. “It’s an ideal solution,” she says. “I switch it on when I’m talking to the whole class, then turn it off when I go round to talk to individual pupils.”

Two other teachers at the school are using the same technology. At pound;459 per set, the equipment is not cheap, but Wombwell head Irene Dalton points out that it is infinitely preferable to losing staff through illness.

Ms Comins warns against relying on hi-tech equipment to rescue you from years of vocal abuse. In any case, a microphone is not always a viable solution. David Brierly, a solicitor for the Professional Association of Teachers, recalls the case of a primary school games teacher whose voice was reduced to a whisper. “He was told it was laryngitis, but when he was eventually referred to a speech therapist, a scan revealed extensive damage to his vocal cords.”

A prolonged effort of trying to save his voice by speaking in a different pitch proved impossible to maintain. A microphone was not only impractical for a games teacher but his voice was too damaged to cope, even with amplification. Last summer he had to leave his job.

“It’s a depressing situation,” says Mr Brierly, “because proper training would have made a difference. We’re not talking about rocket science here. Just a basic grounding in vocal technique would have saved his career.”

Contacts:The Voice Care Network offers individual voice coaching from about pound;50 an hour. Workshops cost around pound;300 per day. It can also put you in touch with local advisers or workshops: Tel 01926 864000; website: www.voicecare.org.uk; email: vcnuk@btconnect.com The Voice and Speech Centre: 01366 386014The Royal College of Speech and Language Therapists: 020 7378 1200Books: More Care For Your Voice, booklet published by Voice Care Network, pound;4.50 (including pamp;p) with discount for buying in bulk. General introduction.Voicecare Factsheet, published by Professional Association of Teachers, tel: 01332 372337, pound;1 for non-members. Includes good advice on health and safety issues and disability allowances.The Right to Speak by Patsy Rodenberg (Methuen pound;9.99). Wide range of information and vocal exercises. Also a video based on the book, entitled A Voice of Your Own, by Kristin Linklater (QSM Drama pound;12.99). More technical exercises.Microphones: Soundranger, tel 01376 572 872; www.soundranger.com

HAPPY TALK: HOW TO HANG ON TO YOUR VOICE

Do

* Drink plenty of water - at least two litres spread over the whole day, not too cold.

* Inhale steam from a bowl of hot water to refresh your voice.

* Articulate clearly - far more important than raising the volume.

* Take care at the start of term, when your voice muscles may be out of practice.

* Use a whistle or bell if you need to attract attention in a noisy room.

* Take up an activity that improves breathing and posture, such as T’ai Chi, Pilates, yoga.

Don’t

* Shout. Ever.

* Clear your throat all the time. It bashes your vocal cords together.

* Eat late at night. Especially spicy food or dairy products.

* Take painkillers for a sore throat. You might do serious damage.

* Whisper to save your voice. It makes things worse.

* Drink too much coffee or alcohol.

Try a workout

Athletes warm up their muscles to avoid injury, and teachers can do the same with their voices each morning.

* Stand upright, feet about 10 inches apart.

* Stretch your arms above your head, then let them relax and flop back to your side.

* Let your head drop to your chest. Move it gently from side to side. Return to middle.

* Breathe in slowly, then sigh out. Repeat six times.

* Breathe in slowly then blow out making a “brrrrr” sound. Repeat six times on slightly different notes.

* Reach down towards your toes, relaxed, then come slowly back up, humming gently. Repeat three times at a different pitch.

* Stretch the back of your throat, as if you were about to yawn. Try to keep in that yawning position while counting to 10.

* Count to 10 again but intoning the words like a chant.

* Relax your shoulders, then repeat step six.

* Finish off by reciting a tongue-twister, or singing gently to yourself.