Localization of audio objects in multichannel reproduction systems
With spatial audio systems the illusion of being in a sound scene should be created, which means to reproduce a natural sound field enveloping the listener. Perceived audio quality is related to the position of the listener in the reproduction room. Former studies indicated that with increased number of loudspeakers for reproduction a larger listening area with high audio quality can be created. In these studies quality was mostly assessed in terms of overall quality or basic audio quality; different factors like distortion, coloration, envelopment and localization were not assessed separately. The new MPEG-H standard should enable high efficiency coding and media delivery in heterogeneous environments. Part 3of MPEG-H deals with the coding and delivery of high-quality 3D audio content, whereas for the producer the number of loudspeaker channels used for reproduction is unknown and flexible. In MPEG the overall audio quality was used for selection of most suitable codin g and rendering algorithm. In addition to the MPEG testing and selection process, we conducted a study on localization performance dependent on listener position, number of loudspeakers and rendering algorithms. A new test method with an innovative testing framework was applied, reducing the influence of visual cues during testing. This method was used to evaluate three different rendering schemes and different loudspeaker setups at three different listening positions. The results showed that reproduction via 22 loudspeakers gives a better localization accuracy compared to 10 and 5 channels. More interestingly, a clear shift of the perceived position of sound objects to the right was observed. In former studies, where the loudspeakers where visible, such a shift could not be observed. This might support our assumption that the vision highly influences the localization perception and therefore listening tests without visual cues are required.