IN AN AGE WHEN we take good care of the visible parts of our bodies - toning and exercising muscles, regulating cholesterol intake, controlling diet, resting eyes and protecting skin - why is it that we seem to take our voices so completely for granted?

For teachers, loss of speech does not simply imply isolation - it may in extreme cases pose a serious occupational threat.

Our voice is the expression of our inner selves and our primary means of communication with the outside world.

Actors and singers, particularly those with trained operatic voices, are accustomed to caring for their vocal cords, resting them when not in use, strengthening them with specific exercises, protecting them from smoky and other damaging environments.

Teachers also use their voices for long periods. They must be able to project so that they can be heard over a large group of energetic students. Occasionally they may be called upon to discipline a pupil or group of pupils.

Despite advances in technology, the main resources in teaching remain "chalk and talk", both irritants of the vocal cords. Yet protection of the voice remains low on the agenda for many teachers.

Patricia Gillivan Murphy is a speech therapist who works on voice problems. She says hoarseness, a common complaint with many teachers, may be caused by a number of factors - from medical or environmental circumstances to vocal misuse or anxiety. In the course of a day's work a teacher may drop pitch, push the voice down to exercise authority and raise it several times to be heard more clearly - all of which can cause wear and tear.

Another cause of voice disorders is excessive strain and tension on the muscles of the larynx area; this can lead to vocal cord nodules and polyps. If a teacher tries to speak for long periods when suffering from laryngitis or a cold, he or she may cause more serious voice problems.

Vocal cords can be damaged by dust, chalk, fumes, strong throat lozenges (believe it or not), neat spirits, tobacco, caffeine, very hot drinks, very spicy foods, cola or a stuffy atmosphere. Bad posture, stress, certain allergies, coughing, tiredness, PMT, emotional upset and background noise may further affect the ability to breathe and speak adequately. Clearing the throat is particularly hard on the voice.

Obviously chalk and talk, tension, stress and background noises cannot be entirely avoided in the school environment - and happily many teachers see out their working lives without ever developing serious vocal problems. Nevertheless, sore throats, laryngitis and more serious problems seem to have a higher than average incidence among teachers.

My own interest in caring for the voice came about as a result of personal experience. For years I used and abused the good strong voice that I had been born with, never experiencing any difficulty beyond the odd sore throat in winter.

In December 1995 I had a fairly, routine operation on my neck and the surgeon warned me of a slight risk of hoarseness after the operation. Unfortunately for me, the slight risk became a very real problem instead of returning to work in a matter of weeks, I was forced to, take extended sick leave to rest my vocal cords.

OVER SOME eight months I worked with a speech and language therapist. She taught me how to strengthen my voice and use it more effectively with the aid of vocal exercises, breath control and relaxation techniques.

Now I can start the day off sounding quite like my old self. However, by the time 5 p.m. comes along I'm hoarse and, like a faulty engine, I simply lose volume and power and splutter out. I waver between the ludicrous heights of Dame Edna Everage on a bad day and the pleasant huskiness of Edna O'Brien on a good day.

Teaching demands a good clear voice, so I found that as the new academic year approached I was as apprehensive. It was as if I were facing a class for the first time.

In August I was still not entirely happy with the state of my voice. The therapist suggested I get a radio microphone pinned to my shirt collar and an amplifier. Although there have been some initial teething problems, overall this has been very successful for me.

Students were naturally curious and amused by the idea to begin with, but they don't even notice now except when they get a little giddy and I pump up the volume.

It's not an ideal situation. There is constant discomfort and a great deal of frustration. However, both principal and colleagues have been very supportive, and I'm grateful that I can still teach effectively.