That's the message Philip Parkin gave to the Professional Association of Teachers' annual conference last week. Parkin, general secretary of the association, said teachers should receive mandatory voice training to help them perform more effectively in the classroom, as speech was the "main tool" for getting children to behave and learn. He said that research showed a link between strength and variation of voice and effectiveness. More than 50% of teachers suffered voice disorders at some stage, he added. "The care and use of the voice should be mandatory in teacher training."