3D sound field recording and reproducing system including sound source orientation

To achieve ultra-realistic communications (URC), a three-dimensional (3D) sound field recording and reproducing system using spatial sound features is promising. It utilizes sound source positions and original source signals as features. On the other hand, sound source orientations (such as speaker´s orientation) have been neglected, though they are necessary for high-performance URC. In this paper, we propose a 3D sound field recording and reproducing system that includes sound source orientation. For the recording part, we applied and evaluated a sound source orientation estimation method based on orientation-extended beamforming. This method requires transfer functions for all possible source positions and orientations, which should be either measured or calculated. Measured transfer functions have high accuracy because all characteristics, such as reverberations and diffractions, are taken into account. Calculated transfer functions are obtained for any environment without measurements. We performed experiments to evaluate the orientation estimation method using transfer functions obtained by both practical measurements and calculations using acoustic simulation based on wave theory. The experimental results show that our estimation method has sufficient capability using both measured and calculated transfer functions. For the reproducing part, we evaluated impulse responses versus sound source orientation. The evaluation results revealed significant differences in both objective and subjective scores. This proves that our system achieves higher performance than conventional ones that do not utilize orientation features.