All members of this family have a vocal core ——piezo disk—— as a means of expressions. When the current runs through the brass and crystal, piezo buckles and rests when there is no current. This is repeated few hundred to few thousand of times ——oscillation—— per second with a pattern determined by the arrangement of their organs. This creates voices. The vibration of piezo vibrates the air, the vibration of air is transferred and hits the eardrums.