Spatially variable parametric sound image presentation with sparsely arranged ultrasonic sources with controlled emission direction

This paper proposes a new method for personalized sound image presentation using parametric arrays with controllable azimuthal direction . Despite a long research history of parametric arrays, few preceding studies handle the issue of subjectively perceived sound source direction. In addition, the control of such virtual parametric sound source directions in practical system configuration remains little practical. To this issue, we propose a solution with much better feasibility, where only several small-sized parametric loudspeakers are supposed to be sparsely arranged with their emission angles controlled depending on the position and attitude of a listener. To this end, we experimentally determined the prediction model of the perceived sound image direction as a function of the sound source position and the direction of ultrasound emission, which was proven to be described as a linear function of those parameters. This paper also discusses how the interaural time difference and interaural level difference influence the sound image position based on acoustic measurement. It was demonstrated that the parametric sound images could be presented reproducibly with our strategy, indicating that our achievement will contribute considerably to the practical possibility of constructing a personalized device-free spatial audio system. • We proposed a practical personal sound image presentation using sparsely arranged parametric loudspeakers. • The emission angles of the loudspeakers are controlled to move the subjectively perceived sound image directions. • We constructed a psychophysical model predicting how the perceived sound image direction depends on the ultrasound emission. • We conducted acoustic measurement to discuss the effects of ILD and ITD on the perceived parametric sound image directions.