Nelson P A, Rose J F W
Institute of Sound and Vibration Research, University of Southampton, Highfield, Southampton 5017 1BJ, United Kingdom.
J Acoust Soc Am. 2005 Jul;118(1):193-204. doi: 10.1121/1.1928787.
This paper deals with the problem of reproducing two signals at two points in space by using two acoustic sources. While much is now known about the techniques available for the design of matrices of inverse filters that enable this objective to be achieved in practice, it is still the basic physics of the sound field produced that controls the effectiveness of such systems and which ultimately dictates their design. The basic physical processes involved in producing the cross-talk cancellation that enables the reproduction of the desired signals is revisited here by using a simple two source/two field point free field model. The singular value decomposition is used to identify those frequencies where the inversion problem becomes ill-conditioned and to explain physically the origin of the ill-conditioning. As observed previously, it is found that cross-talk cancellation becomes problematic when the path length difference between the two sources and one of the field points becomes equal to one half the acoustic wavelength. The ill-conditioned frequencies are also found to be associated with a limited spatial region of cross-talk cancellation and with large source outputs manifested in the time domain by responses of long duration.
本文探讨了利用两个声源在空间中的两个点再现两个信号的问题。虽然目前对于能够在实践中实现这一目标的逆滤波器矩阵设计技术已有很多了解，但仍然是所产生声场的基本物理特性控制着此类系统的有效性，并最终决定其设计。本文通过使用一个简单的双源/双场点自由场模型，重新审视了实现串扰消除从而再现所需信号所涉及的基本物理过程。奇异值分解用于识别反演问题变得病态的那些频率，并从物理上解释病态的根源。如先前观察到的，当两个声源与其中一个场点之间的路径长度差等于声波波长的一半时，串扰消除会出现问题。还发现病态频率与串扰消除的有限空间区域以及在时域中表现为长时间响应的大源输出有关。
