Adaptive Adjustment of the ”Sweet Spot“ for Head Rotation

Spatial reproduction in a conventional stereophonic audio system (e.g., stereo or 5.1 surround) works in a small area known as the ”sweet spot“. If the listener changes his position, the phantom source moves in the same direction and finally collapses into the nearer loudspeaker. A play-back system that adjusts the loudspeaker signals depending only on the listener’s position in real-time was evaluated in a previous study. Additionally, the orientation of the head in relation to the loudspeaker setup has an influence on phantom source localization. Localization errors that occur when the head is turned are discussed in this article. For this purpose a binaural localization model is used. It shows that the auditory event moves towards the median plane of the listener. This effect becomes stronger as the original phantom source position deviates further from the median plane. A compensation function is proposed and evaluated. Stable phantom source localization can be achieved using adaptive signal adjustment depending on the listener position and orientation.