# Auditory Localization in Low-Bitrate Compressed Ambisonic Scenes
## 5 Discussion  
Multiple factors have contributed to the localization error measured during the experiment. Firstly, the limited resolution of the human auditory localization in 3D space, which has been briefly described in Section 2. This study was focused on directions where the localization blur is relatively high, which may have contributed to the high variance in the responses. The measured median localization error for the 5 th-order uncompressed reference reproduced over loudspeaker array was about 11\({}^{\circ}\), which is comparable with other studies focusing on localization in horizontal and vertical planes combined [48]. Secondarily, the limited-order Ambsonic representation of the target and acoustic pointer scenes has contributed to the localization error. The results prove that localization precision is largely defined by the Ambsonic order, as higher orders present more precise spatial resolution. The median localization error for the 1 st-order scenes was about 34\({}^{\circ}\)what corresponds to the results obtained by [PERSON] [29] for the virtual sound source presented over the loudspeaker array. The localization error obtained in the same study for the 4 th-order Ambsonic virtual sources was about 10\({}^{\circ}\), what corresponds indirectly to our 5 th-order uncompressed condition result. In the experiment by [PERSON] [30], the localization error for 4 th-order Ambsonic virtual sources measured in the horizontal plane varied from 5\({}^{\circ}\) to 14\({}^{\circ}\) at the lateral positions. It is important to note that our experiment used virtual sound source presentation for both target and pointer sounds to facilitate the headphone-based tests, where the study by [PERSON] was done with an Ambsonic pointer and real sound source target. A direct comparison of our results with any of the referenced studies is not possible due to the differences in reproduction systems and test frameworks. Another source of error comes from the limitations of the reproduction methods used. Participants who took part in loudspeaker tests localized the sound sources with the highest precision. A similar degree of precision was obtained using binaural reproduction with individually measured HRTFs at 1 st Ambsonic order. At 3 rd and 5 th-order, the localization error in headphone-based tests was higher than in the loudspeaker-based phase. Binaural reproduction of Ambsonic scenes employing the generic HRTF set resulted in the highest localization error at all tested signal conditions. This phenomenon requires further investigation, as the loudspeaker and headphone test data were obtained with different groups of participants. It is worth noting that the lowest bit rate in 3 rd-order Ambsonic presentations (256 kbps) produced a significantly improved localization precision in the loudspeaker case than the highest bit rate condition for 1 st order (also 256 kbps). In both headphone listening cases there is no significant difference between the aforementioned bitrates and orders. These results are contrary to those found by [PERSON] et al. which show a significant degradation with the lowest bitrate at 3 rd order [36]. We attribute these differences to the use of head-tracking and the greater localization-performance test paradigm of this study rather than perceived overall quality. The results of this study show that auditory localization in low-bitrate compressed Ambsonic scenes is not significantly affected by codec parameters. Although the differences between localization error for the same orders are not statistically significant, based on visible trends it can be seen that localization precision does degrade slightly with lower bitrate compression. The other studies focused on timbral fidelity of the Opus compressed spatial audio revealed significant differences between bitrates and Ambsonic orders [32]. The effect of an additional soundscape present in test stimuli was investigated; however, no significant difference was observed between simple and complex content presentations.