Introduction to modeling and analysis of small, piezoelectrically excited bending-wave loudspeakers

Piezoelectric patches are used to excite panels into bending vibration, allowing the screens or cases of smartphones, tablets, laptops, and other small electronic devices to produce sound without traditional microspeakers. This paper presents an introduction to modeling and analyzing the acoustic response of such devices, assuming the use of a piezoelectric patch exciter driven with a 10 VRMS signal. Simulations are performed with respect to four design factors (piezoelectric patch size, piezoelectric patch location, panel material, and panel enclosure depth) as well as three performance metrics [low-frequency cutoff point, mean sound pressure level (SPL) above cutoff, and the standard deviation of SPL above cutoff]. Results demonstrate several key relationships, such as: larger patch sizes create higher mean SPLs, smaller enclosures create higher mean SPLs but also higher cutoff points, and larger enclosures create more deviation in the measured SPL. Additional design factors are identified and discussed which will impact practical designs.