You're talking for around five hours a day, every day, but if you have a parents' evening, it can be nearer to eight hours.
I've been in teaching for more than 20 years, but it was only five or six years ago that I started having problems. I'm asthmatic, which probably doesn't help, and classrooms aren't as quiet as they used to be, so you're raising your voice a lot of the time. On one occasion I lost my voice so badly that I had to pass a note to the doctor to explain what was wrong with me. I literally couldn't say a word. The doctor just shook his head and said: "Singers, actors and teachers; it's always the same."
I realised I needed to do something to save my voice, so I approached my headteacher and asked about the possibility of some kind of microphone to help me. He agreed, and the school purchased a system from Soundranger. It is excellent. You wear a headset, rather like the ones pop stars use, and you speak into the mouthpiece in a normal voice. Your voice is amplified through speakers that can be positioned wherever you want in the classroom.
It's strange for a while, but then you forget you're using it. There's a bit of a novelty factor for the pupils too, though, again, they soon get used to it. The only problem was that a colleague got the same system at the same time, and until we got our frequencies sorted out, my voice kept coming through in her room and vice versa. Very confusing for everybody.
I started off using the Soundranger every day, but now my voice has recovered I rarely need it, maybe just the odd lesson here and there. In any case, since I started having voice trouble I've adjusted my teaching style and I don't talk as much as I used to. I try to plan my lessons so there is some time for pupils to get on by themselves.
Most schools would benefit from having a couple of microphones that can be shared when staff have problems. They cost a few hundred pounds, and if someone is off because of vocal problems, the cost of supply will be far more than that. It's not a case of having one day off if you lose your voice; it's taken me two to three weeks to recover.
The long autumn term is definitely the worst time for teachers struggling with their voices. Lots of colleagues are coughing, croaking or hoarse. You get people apologising in the staffroom for not being able to have a chat with you because they have a sore throat. I know a teacher who has serious problems - it looks as though there may be nodules on the vocal cords, which could threaten the person's career.
I'm lucky in that the room where I teach has good acoustics, though when I cover lessons around the school I find some classrooms more difficult. If there's any kind of echo in a room you end up raising your voice to compete.
I look after my voice much more now. The consultant I saw taught me the importance of keeping my voice hydrated. Every evening I hold my head over a bowl of steam and inhale - you can feel the soothing effect on your vocal cords - and I'm never without a bottle of water in school.
But why had I never been told this before? There's definitely a case for proper voice training for all teachers at college. I'm a county secretary for the National Association of Schoolmasters Union of Women Teachers and, from a union perspective, schools are in breach of their duty of care if they don't make sure employees know how to use their voice safely and effectively.
Jim Goodall teaches chemistry at Abersychan comprehensive school in Torfaen, Wales