Upper hemisphere sound image control with horizontal-arranged loudspeakers based on parametric head-related transfer functions

Abstract

The 22.2 multichannel sound system has been developed for an ultra high-definition television system. This system consists of twenty two loudspeakers and two sub-woofers called low frequency effects, and can reproduce three-dimensional sound image appropriate to the ultra high-definition television system. However, this system has a problem of high cost to install. On the other hand, the multichannel sound system with horizontal-arranged loudspeakers has lower cost to install than full scale one. However, this system cannot reproduce an upper sound image. Therefore, in this paper, we propose the upper sound image control with horizontal-arranged loudspeakers based on the parametric head-related transfer functions. The proposed method generates binaural signals to control the sound image elevationally based on the parametric head-related transfer functions in the median plane. Also, the proposed system uses the interaural level difference to control the sound image of binaural signals azimuthally. Finally, the proposed method generates output signals for horizontal-arranged loudspeakers from binaural signals by designing a multichannel inverse system based on multi-input / output inverse theorem. The experimental results show that the proposed method can control the sound image to elevation angle with the same accuracy as binaural lreproduction. The 22.2 multichannel sound system has been developed for an ultra high-definition television system. This system consists of twenty loudspeakers and two sub-woofers called low frequency effects, and can reproduce three-dimensional sound image appropriate to the ultra high-definition television system. However, this system has a problem of high cost to install. On the other hand, the multichannel sound system with horizontal-arranged loudspeakers has lower cost to install than full scale one. However, this system cannot reproduce an upper sound image. Therefore, in this paper, we propose the upper sound image control with horizontal-arranged loudspeakers based on the parametric head-related transfer functions. The proposed method generates binaural signals to control the sound image elevationally based on the parametric head-related transfer functions in the median plane. Also, the proposed system uses the interaural level difference to control the sound image of binaural signals azimuthally. Finally, the proposed method generates output signals for horizontal-arranged loudspeakers from binaural signals by designing a multichannel inverse system based on multi-input / output inverse theorem. The experimental results show that the proposed method can control the sound image to elevation angle with the same accuracy as binaural reproduction.