Reproduction of varied sound image localization for real source in stereo audio system

In this paper, we propose a sound reproduction system which can realize varied sound image localization in stereo audio systems. The proposed system can suppress unnatural variations of sound image localization with listener´s movement and maintain the absolute position of sound image so that a real source exists in the corresponding position. Generally, human being perceives the direction of sound image on horizontal plane according to Interaural Level Difference (ILD) and Interaural Time Difference (ITD) between signals arriving at both ears. Accordingly, unnatural variation of sound image localization accompanying listener´s movement is due to the differences of ILD and ITD between the stereo audio system and the real source. The proposed system therefore compensates ILD and ITD using digital filters. Some subjective assessment tests with ten subjects demonstrate that fixed sound image can be realized in the proposed system when listener moves away by giving appropriate signal level ratios.