A Measure Based on Beamforming Power for Evaluation of Sound Field Reproduction Performance

Ji-Ho Chang,Cheol-Ho Jeong

doi:10.3390/app7030249

Abstract

This paper proposes a measure to evaluate sound field reproduction systems with an array of loudspeakers. The spatially-averaged squared error of the sound pressure between the desired and the reproduced field, namely the spatial error, has been widely used, which has considerable problems in two conditions. First, in non-anechoic conditions, room reflections substantially deteriorate the spatial error, although these room reflections affect human localization to a lesser degree. Second, for 2.5-dimensional reproduction of spherical waves, the spatial error increases consistently due to the difference in the amplitude decay rate, whereas the degradation of human localization performance is limited. The measure proposed in this study is based on the beamforming powers of the desired and the reproduced fields. Simulation and experimental results show that the proposed measure is less sensitive to room reflections and the amplitude decay than the spatial error, which is likely to agree better with the human perception of source localization.

Highlights

Sound field reproduction methods, such as higher-order ambisonics (HOA) [1,2,3,4,5,6,7,8] and wave field synthesis (WFS) [9,10,11], attempt to reproduce a sound field that is similar both physically and perceptually to what is intended
Sound field reproduction systems using those reproduction methods have been implemented in several places [16,17,18,19,20,21,22,23,24,25,26,27], and there have been a number of studies on physical validations [17,18,25,26,28,29,30] and perceptual evaluations [17,18,19,20,22,28,30,31,32,33] with the reproduction systems
In order to overcome the limitations of the spatial error, the present study proposes a measure based on the beamforming power, or the beam-power

Summary

Introduction

Sound field reproduction methods, such as higher-order ambisonics (HOA) [1,2,3,4,5,6,7,8] and wave field synthesis (WFS) [9,10,11], attempt to reproduce a sound field that is similar both physically and perceptually to what is intended. Sound field reproduction systems using those reproduction methods have been implemented in several places [16,17,18,19,20,21,22,23,24,25,26,27], and there have been a number of studies on physical validations [17,18,25,26,28,29,30] and perceptual evaluations [17,18,19,20,22,28,30,31,32,33] with the reproduction systems. There are spatial [17,18,25,26,28,30], temporal, and spectral features [29] in the physical validations, which are related to perceptual attributes, such as localization, source width, and sound quality. The spatial error does not always correspond to human localization [29]

Objectives

Discussion

Conclusion