Design of parametric loudspeaker

Based on parametric array theory and nonlinear acoustic interaction theory, a parametric loudspeaker (a type of directional sound generator) was designed and implemented in this project. A parametric loudspeaker modulates and transmits audio signal with ultrasound carrier, and demodulates the signal with nonlinear interaction in air. The parametric loudspeaker designed in this project consists of four parts, signal processing circuit, audio amplifier, DC-DC voltage convertor and ultrasound transducers array, of which the DC-DC voltage convertor was not contained in other typical parametric loudspeakers. The signal processing part was designed based on square-root amplitude modulation (SRAM) theory, and double-integration was utilized in the signal pre-processing stage to reduce nonlinear distortion of parametric array. The addition of the DC-DC voltage convertor help to boost the voltage of amplified signal to drive the ultrasound emitter, and thus the required operation voltage of this design was reduced by 2/3, which means the power-consumption of this parametric loudspeaker could be much lower than a typical one. This project was to test the feasibility to solve the high power-consumption problem of parametric loudspeaker with this method.Bachelor of Engineerin