Perceptual Evaluation Of Bitrate Compressed Ambisonic Scenes In Loudspeaker Based Reproduction

The increasing popularity of Ambisonics as a spatial audio format for streaming services poses new challenges to existing audio coding techniques. This paper seeks to evaluate timbral distortion and localization accuracy of Ambisonic audio encoded using Opus low-bitrate compression. The study was conducted for 1st, 3rd and 5th order Ambisonic signals at various bitrates reproduced over a 50-channel spherical loudspeaker configuration. This study has identified how lower bitrates reduce timbral fidelity, though this changes depending on the audio content. Localization accuracy has been found to be relatively robust even at very low bitrates. The results suggest that the user experience of spatial audio streaming services would significantly improve if 3rd order Ambisonics would be implemented over 1st order.