The piezoelectric effect is used to do this[0]. This other wiki page[1] has some neat pictures of what the sound field looks like. [0] https://en.wikipedia.org

The piezoelectric effect is used to do this[0]. This other wiki page[1] has some neat pictures of what the sound field looks like. [0] https://en.wikipedia.org/wiki/Ultrasonic_transducer https://en.wikipedia.org/wiki/Ultrasonic_transducer [1] https://en.wikipedia.org/wiki/Ultrasonic_transducer#Transducers https://en.wikipedia.org/wiki/Ultrasonic_transducer#Transduc...