Conversion Between Stereo And Multichannel Surround

With the development of high performance computer and digital signal processing, "virtual reality" is a widely studied subject recently. The technology of virtual reality reconstruction develop quickly in recent years, which is an interdisciplinary subject and involves many research areas, such as hearing, auditory physiology, psychology, artificial intelligence and high performance computer system etc.Because of the excellent sound effect, 5.1 channel surround sound system has been widely applied in our daily life, and the audio files are also increased dramatically. But considering the existing audio playback devices, the mainstream is still traditionally two channel stereo systems. So it is of practical significance to study how to play for the 5.1 channel surround sound audios in the stereo system devices and maintains the sound effect of the multichannel surround sound at the same time. In this paper, we analyses the conversion technology based on the traditional head related transfer function(HRTF). In order to increase the ambience and stereo feeling when playing the audio files, we propose the rear image synthesis method to generate of the rear surround sound signal, which is based on three dimensional space around the HRTF. Experiments show that: this method increases stereo surround feeling after the conversion to two channel stereo.Similarly, it is also of practical significance to explore how to play two channel stereo audio files directly through 5.1 channel surround sound playback system and also make the listener experience obvious sense of the scene and the surrounding feeling in auditory perception. Based on the discussion of the traditional conversion techniques, we focus on the rear two channels surround sound signal generating methods. We mainly process the rear channel signals by divided into different sub bands. First, decorrelation is processed in each sub band. Then we use three dimensional space HRTF convolution processing. Thus the converted surround sound has been extended to three dimensional space from the horizontal plane. Hearing experiments prove that this method enhances the surround sound effect.