Bionic Acoustic Camera

Authors: Benedikt Bugl1, Viola Schneider1, Armin Sehr1

1OTH Regensburg

Background: In contrast to the sense of sight, where (sensory) neural structures are organized according to the angles of incidence of the light, spatial sound perception functions completely differently. Binaural and monaural cues regarding arrival time differences, level differences and frequency patterns are processed in complex neural structures. A deeper understanding of the processing can help improve hearing aids regarding the cocktail-party-problem, as well as spatial and virtual audio.
Method: As a testing platform for localization algorithms, a Bionic Acoustic Camera is implemented using an artificial head and a wide-angle camera. Head-related transfer functions (HRTFs) of the artificial head are measured. Localization algorithms (found in literature, as well as self-developed) using the HRTF dataset and the signals from the ears are implemented and tested in anechoic, as well as in reverberant conditions. Imitating the known neural structure of the auditory pathway a real time demonstrator system is set up – the bionic acoustic camera.
Results: Overall, the algorithms show varying results. The cross-channel algorithm delivers especially promising results, surpassing human performance, if given an HRTF dataset with higher angle resolution. In reverberant conditions, none of the tested algorithms can match the robustness of spatial hearing. Reverberation and reflections greatly disturb especially the estimation of the elevation angle.
Conclusions: The robustness advantage of spatial hearing in reverberant conditions poses a great chance to improve algorithms by understanding the processing in the hearing pathway, especially regarding the precedence effect. Furthermore, the algorithm tests show the importance of a separate HRTF-dataset for the generation of test signals, showing otherwise undetected weaknesses in real-world conditions. Also, a lack of data on spatial hearing precision in the median plane is found, which will be investigated in future work.