Controlling a distance from linear loudspeaker arrays to a listening point by using tangent line method.

Tsutomu Kaizuka

doi:10.1121/10.0005602

Abstract

A technique for confining the acoustic fields near loudspeaker arrays is proposed for personal audio systems. The proposed technique is based on tangent line method (TLM), which enables the production of circular acoustic beams. The produced beams are focused at a point designated as the listening point. Performance of the TLM-based method and acoustic contrast control (ACC) is compared. In terms of the acoustic contrast and array effort, the TLM-based method is not superior to the ACC but is comparable with the ACC under certain conditions. The advantage of the TLM-based method is the simplicity in signal processing.

Highlights

Confining the acoustic fields near acoustic sources can be used to realize personal audio systems in which the sound is audible in the nearby listening zone, but silence is maintained elsewhere
The proposed technique is based on tangent line method (TLM), which enables the production of circular acoustic beams
The TLM was applied to produce a quarter-circle of an acoustic field using a linear loudspeaker array

Summary

Introduction

Confining the acoustic fields near acoustic sources can be used to realize personal audio systems in which the sound is audible in the nearby listening zone, but silence is maintained elsewhere. Pressure matching is an optimization method to match reproduced acoustic fields to target acoustic fields, where the target acoustic field in the non-listening zone is zero for the application of personal audio systems This literature focused on pressure matching with three loudspeakers and revealed that it could be represented by a broadside differential array, which simplified the implementation. According to the above literature review, there is no established method for simultaneously providing three-dimensional acoustic confinement, a simple layout for the loudspeaker array, and listening zones not limited to the near-field, all while avoiding the use of ultrasonic waves. In the present study, based on crossing the arc-shaped acoustic beams, the listening point is produced at a designated distance from the linear loudspeaker arrays.

Theory

Numerical examples

Findings

Conclusion