"Phil Hobbs" wrote in message
...
It couldn't generate any sound unless its input impedance has a resisitive
component--it would violate conservation of energy. (And even a pure
capacitor would see a decrease in voltage swing if a series resistance
were added.)

This is a good source of information on piezo actuators/transducers
http://www.physikinstrumente.com/en/...o_tutorial.php