Effects of down-mix algorithms on quality of surround sound

Eight down-mix algorithms were evaluated in terms of basic audio quality. The investigation was focused on the standard 5.1 multichannel audio setup (ITU-R BS.775-1) and limited to two listening positions. The results obtained are summarized and detailed specifications of the subjectively best algorithms are given. The effect of the. presentation of moving pictures on the assessment of audio quality was also investigated. The results show that the exposure to a visual content has a considerable effect on the evaluation of the audio quality at the off-center position to some types of program material.