Piezoeffect: direct or inverse?

Did you know that piezoeffect can be direct or inverse?!

Direct piezoeffect

The direct piezoeffect, also called the sensor effect is caused when piezo material reacts on mechanical pressure and converts mechanical energy into electrical energy. 

 Inverse Piezoeffect 

Sonitron’s piezo audio components work with the inverse effect, which means that the piezo material responds to voltage variations, converting electrical energy into mechanical motion. Eventually this generates a sound wave!