Piezo loudspeakers use the piezo effect, whereby applying a voltage to a crystal causes it to bend. Because such loudspeakers can be extremely small and lightweight, and also require little energy and no large resonant volumes, they are ideal for mobile devices such as notebooks, tablet PCs, smartphones and cell phones.
Piezo loudspeakers work with bending transducers made of very thin piezoceramics that are contacted on both sides with electrodes. The small deflection of the piezo ceramic is transmitted to a diaphragm and thus generates the sound.
The thickness of such speakers is less than 1 mm and their weight less than 1 gram. Although piezo speakers have only small diameters of about 20 mm, the sound reproduction is relatively good, especially of course at higher frequencies. The frequency range of such speakers is between 300 Hz and 20 kHz with a sound pressure that is quite comparable to dynamic speakers.