We have all had them: the narcolepsy-inducing teacher whose lifeless tone lulls all but the most energetic to sleep.
But such mind-numbingly dull experiences could become a thing of the past as voice coaching techniques are increasingly being taught to trainee and qualified teachers. Sussex University was one of the first to provide such training in 1989 to counter monotonous lessons and the danger of work-related voice damage.
"You wouldn't expect a surgeon to be taught anatomy but not how to use a scalpel, so why are teachers still not being taught how to use their instruments - their voices?" asks James Williams, a science lecturer at the university. He has been an actor and a classroom teacher and knows more than most about how the voice can entertain and educate, or take all the joy out of learning.
"Teaching is a series of performances. But the audience keeps changing and is a lot more critical and discerning than you find in a theatre," he says.
"How you use your voice determines how switched on the children remain."
The Royal Shakespeare Company believes voice coaching is just as important for teachers as it is for actors and it conducts workshops with teachers to make them more aware of how to use the voice as an effective communication tool.
"The voice is the bedrock of teaching and communicating but it remains a seriously neglected area," says Lyn Darnley, head of voice at the RSC and co-author of The Teaching Voice. "I've seen teachers lose control of the class as a direct result of poor projection. Women's voices in particular can become very high-pitched when they are tense and this in turn undermines their status among pupils and can lead to bad behaviour."
Ann Thomas, who set up Sussex University's voice training programme, insists that any coaching should be conducted by experts who understand the physiology of the voice. "Experts can nip significant problems in the bud and give advice on how to change the posture, breathing, pitch and resonance so the voice can be protected," she says. "We can also advise on pace. A lot of student teachers are nervous, which makes them speak faster.
You have to give pupils time to take things in and note them down."
Trainee teachers at Sussex receive sessions on how to use and protect their voices, as well as a written report on their performance. And if placement schools are unhappy with their student teachers' voice skills, Ann is sent in to help.
The consequences of doing nothing are far reaching. In 2003, Jemma Rogerson, a speech therapist from Chorley, Lancashire, conducted a study into the impact of a damaged voice on a teacher's effectiveness. It found that any form of vocal impairment had an impact on half of pupils.
"The report shows that a damaged voice is not only unpleasant for the teacher but it could also have a severely negative educational effect,"
Such findings have massive implications when considering the extent of voice damage in the profession.
According to the Voice Care Network, which coaches some 4,000 trainee teachers a year, one in 10 long-servers will find themselves in a voice clinic at some point of their career. Further independent studies suggest that half of all teachers will experience some sort of vocal dysfunction during their working life. It is paramount they maintain a robust and animated voice, because without it their career is over. The voice reflects the health of the body and any tension in the posture will be heard, says Louise Crowley, the senior coach at Professional Voice, a communication teaching service. She believes schools are becoming increasingly aware that the voice needs to be nurtured if teachers are to raise standards. "How we develop the resonance, range and projection of the voice infuses teaching with a sense of drama and excitement," she says.
When Sue Cowley, author of Getting the Buggers to Behave, goes into schools to give voice workshops, she finds primary teachers are generally better at expressing themselves vocally than secondary teachers, because varied and exaggerated tones are used more readily with younger pupils. However, the majority of newly-qualified teachers she meets tell her they have lost their voice or had sore throats at some point during their short teaching career.
She says. "Some people find it hard to understand what I mean when I suggest that they add tone to their voice, and these teachers are often the physically static ones as well. They are the ones who must learn how to use their voices correctly before it's too late."
I DIDN'T REALISE MY VOICE MIGHT HAVE A SELL-BY DATE
Heather, 52, has been teaching for more than 30 years at secondary schools in Brighton without any significant voice problems. But during the past couple of years, she felt her voice was becoming weaker. Then, a month ago, she taught six lessons on the trot followed by a busy two-hour parents'
"I've had bad throats before but nothing like this," she says. "My voice went completely and I've had total voice loss for the past two weeks."
Heather is due to have a laryngoscopy, which should lead to a firm diagnosis. But in the meantime, she has been left with almost no voice and the threat of permanent damage.
"I didn't realise my voice might have a sell-by date. I want to return to the classroom but if I do, I'll make sure I don't speak over noise and I want to replace my old fan, PC and data projector, all of which are loud and dry the air."
She wishes she'd been taught how to care for her voice so she could have avoided certain triggers. "I'd never even realised that tea dries the larynx," she says. "We need more training days in school. Only then will teachers learn that voices really can just go."
HOW TO AVOID VOCAL STRESS
* Keep hydrated: drink plenty of water and avoid heavy smoking, excessive alcohol and spicy food.
* Maintain an aligned and released posture.
* Keep the muscles of the shoulders, neck and jaw released with gentle stretching exercises every day.
* Breathe from the "centre" muscles of the lower ribs and abdomen to support the voice.
* Warm up the voice daily with gentle humming, sliding up and down the pitch scale, and a few tongue-twisters.
* Do not shout over background noise. Use a whistle, bell or clapping to get attention.
* Humidify the classroom with bowls of water near radiators and ventilate whenever possible.
* If you have a cold, make sure you rest the voice.
* Try not to clear the throat excessively, it is like rubbing sandpaper on the vocal folds. Swallow hard instead or try sipping water.
* If hoarseness persists for longer than three weeks, consult your doctor or an ear, nose and throat specialist.
PUT AN END TO THAT DREARY MONOTONE
* Record yourself teaching and listen to it. Ask others how they perceive your voice and make changes accordingly.
* Listen to a radio DJ or a good talking book and note how the speakers vary their pitch, speed and tone to entertain.
* Use your body to express emotion as well as your voice.
* Take time to breathe - this will slow down your delivery, allow you to collect your thoughts and avoid strain on the voice.
* Practice counting between one to 20, starting off with a monotonous voice and then gradually becoming over-excited. This will make the rest of your body come alive.
* Focus on the meaning of what you are saying, especially if reading aloud.
* Put emphasis on key words or sentences.