Driver placement for selective modal excitation in flat-panel loudspeakers

Abstract

The audio quality of flat panel loudspeakers may be improved dramatically by selectively driving specific panel modes using an array of force actuators distributed on the panel surface. An optimal actuator array layout will maximize the energy coupling between the actuators and selected panel modes, while simultaneously eliminating modal crosstalk within the operating frequency band. We present results for optimal force actuator array layouts for both dynamic force actuators and piezoelectric patch actuators. Experiments on panel loudspeakers using optimized force actuator array layouts show that each of the panel modes within the tuning bandwidth may be independently addressed, and that the optimized array can limit the inter-modal crosstalk between −17 dB and −22 dB within the bandwidth using non-ideal force transducers. The methods described may also be useful in structural vibration control and noise reduction.