Sound Field Reproduction by Wavefront Synthesis Using Directly Aligned Multi Point Control

Noriyoshi KAMADO  Haruhide HOKARI  Shoji SHIMADA  Hiroshi SARUWATARI  Kiyohiro SHIKANO  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E94-A   No.3   pp.907-920
Publication Date: 2011/03/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E94.A.907
Print ISSN: 0916-8508
Type of Manuscript: PAPER
Category: Engineering Acoustics
wavefront synthesis,  wavefront measurement,  impulse response,  multi-point control,  

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In this paper, we present a comparative study on directly aligned multi point controlled wavefront synthesis (DMCWS) and wave field synthesis (WFS) for the realization of a high-accuracy sound reproduction system, and the amplitude, phase and attenuation characteristics of the wavefronts generated by DMCWS and WFS are assessed. First, in the case of DMCWS, we derived an optimal control-line coordinate based on a numerical analysis. Next, the results of computer simulations revealed that the wavefront in DMCWS has wide applicability in both the spatial and frequency domains with small amplitude and phase errors, particularly above the spatial aliasing frequency in WFS, and we clarified that the amplitude error in DMCWS has similar behavior to the well-known approximate expression for spatial decay in WFS; this implies the ease of taking into account estimating the amplitude error in DMCWS. Finally, we developed wavefront measurement system and measured a DMCWS wavefront using our wavefront measurement system and algorithm. The results of measurements clarified the frequency characteristics of a loudspeaker. Also, DMCWS has wide applicability in frequency domains in actual environments. From these findings, we concluded the advantageousness of DMCWS compared with WFS.