Reverse piezoelectric effect in crystal
No need to make inventions. Piezoelectric speakers are still widely used as tweeters. Piezoelectric (=crystal) earphones were popular in the past due their high sensitivity.

Ultrasonic devices use piezoelectric transmitters.

The high pitched buzzers have most often a piezoelectric sounder.

Nearly all clocks, computers and modern radio equipment have crystal oscillators. They have a quarz crystal that mechanically vibrates due the piezoelectricity

Addendum:  The crystal is connected to an output of an amplifier or other circuit that produces the wanted AC voltage. The oscillator is a special case. The crystall is the feedback route between the input and output of an amplifier. This makes the circuit to oscillate just like an audio PA system squeals when the microphone is too near the speaker. The crystal makes the frequency stable and well defined.

The presented devices create mechanical vibrations fron the voltage changes. The reverse of this is used in the following devices:


oscillator crystals (they act in both directions at the same time)
crystal microphone
ultrasonic receiver
crystal pickup for a player for vinyle records
acceleration sensor
pressure sensor
knock detector