Visualization of demodulated sound based on sequential acoustic-ray-tracing for parametric array loudspeakers in three-dimensional space

Recently, the demand for sound visualization is increasing. Sound visualization is to visually grasp the spread of sound. When arranging loudspeakers, it is required to determine the position and direction of the loudspeakers. Conventionally, acoustic-ray-tracing has been proposed as a sound visualization method. This conventional method visualizes the audible wave which is emitted from the loudspeaker. However, it is difficult to visualize the demodulated sound of a parametric array loudspeaker (PAL) whose directivity is sharp because that is generated by nonlinear interaction in the air. To solve this problem, we propose a visualization of demodulated sounds based on sequential acoustic-ray-tracing for PAL in three-dimensional (3-D) space. A sequential acoustic-ray is an acoustic-ray generated by discretizing space and time. The proposed method produces sequential acoustic-rays for spatial sound sources in two-dimensional space to approximate the demodulation phenomenon that generates spatial sound sources. Furthermore, this method is extended to 3-D space using affine transformation. From the above, the proposed method visualizes the demodulated sound of PAL in practical applications. Experimental results indicate the effectiveness of the proposed method.