Glossary:Piezo
The piezo-electric effect is the property of some materials to develop a voltage across two opposite faces when a physical force is applied, or to stretch or squeeze slightly if a voltage is applied. Pronounced "pee-ayzo" by some and "pee-zo" by others. The Oxford Dictionary allows either, but wars have been started over less contentious issues. Used in some microphones and earpieces, quartz crystal frequency standards, and gas lighters.