Design and validation of a private audio zone using ultrasonic arrays

• Main Author: Liu, Qirui
• Other Authors: Chang Joseph
• Format: Thesis-Master by Coursework
• Language: English
• Published: Nanyang Technological University 2023
• Subjects: Engineering::Electrical and electronic engineering
• Online Access: https://hdl.handle.net/10356/169975
• Institution: Nanyang Technological University

This dissertation addresses one of the limitations of conventional speakers, specifically that they lack privacy in their acoustical output due to their omnidirectional sound production and propagation. In contrast, the parametric acoustic array (PAA) can create highly directional sound beams via the nonlinear effect of air. Nevertheless, PAA albeit producing a more directional acoustical output, it is unable to provide an acoustical output that is restricted within a specific area – an acoustical privacy zone. In this dissertation, we attempt to create the said acoustically privacy zone. We first introduce the working principle of the PAA and provide a calculation method for its demodulation signal. Our proposed approach involves dividing the amplitude-modulated signal in the PAA into two phase-modulated signals, which are loaded into two transducer arrays. The demodulated envelope signal is generated in an area where the two beams intersect, thereby limiting the generation of demodulation signals within a certain area – the acoustically privacy zone. We implemented the proposed PAA device and conducted experiments to verify our approach, which showed promising results.