Study on Virtual Sound Field Reproductive Processing and its Reciprocal Relation in Multimedia Signals.

数字信号处理的最新进展使得基于高保真声音信号再现三维声场成为可能。利用头部相关传递函数（hrtf）模拟双耳信号再现虚拟声场，利用FIR滤波器对声音图像进行定位是最重要的技术之一。然而，由于FIR滤波器的阶数极高，使用FIR滤波器控制声场非常困难。从这个角度来看。我们提出了一种使用HR滤波器实现声音图像定位的简单方法。在过滤过程中。比如乘法运算。与FIR滤波器相比，这种方法可以将成本降低到1/15到1/30。在我们的一些实验中，在使用FIR滤波器和HR滤波器的两种情况下，双耳信号通过两个扬声器再现。进行了局部化实验。结果是。在水平面上使用HR滤波器的声音定位与使用FIR滤波器的情况几乎相似。结果表明，利用HR滤波器的hrtf近似技术可以有效地实现声音在水平面上的定位。然而，高频滤波器相位特性的非线性会导致声音定位精度的降低。通过带噪声实验，得出了最大相位误差不超过10度的结论。

Recent progress in digital signal processing has made it possible to reproduce 3D sound fields based on high fidelity sound signals. It is regarded the method for localizing sound images using FIR filters is one of the most important techniques for virtual sound field reproduction by using binaural signals simulated by head-related transfer functions (HRTFs). However it is very difficult to control the sound field by using the FIR filters because of extreme higher orders of those filters. In this point of view. We propose a simple method using HR filters for realizing sound image localization. In the filtering process. such as the multiplication operation. this method can reduce the cost to possibly 1/15 to 1/30 as compared with the FIR filters. In our some experiments, binaural signals are reproduced via two loudspeakers in both case of using the FIR filter and the HR filters. Some localization experiments are carried out. As the result. the sound localization on the horizontal plane using the HR filters was almost similar to the case of using the FIR filters. It is shown that the approximation technique of HRTFs using the HR filters is effective for the sound localization on the horizontal plane. However, the non-linearity of phase characteristics of the HR filters may cause decrease of the sound localization accuracy. We conclude the largest phase error is at most about 10 degrees difference in phase characteristics through some experiments using band noises.