Online learning for template-based multi-channel ego noise estimation

This paper presents a system that gives a robot the ability to diminish its own disturbing noise (i.e., ego noise) by utilizing template-based ego noise estimation, an algorithm previously developed by the authors. In pursuit of an autonomous, online and adaptive template learning system in this work, we specifically focus on eliminating the requirement of an offline training session performed in advance to build the essential templates, which represent the ego noise. The idea of discriminating ego noise from all other sound sources in the environment enables the robot to learn the templates online without requiring any prior information. Based on the directionality/diffuseness of the sound sources, the robot can easily decide whether the template should be discarded because it is corrupted by external noises, or it should be inserted into the database because the template consists of pure ego noise only. Furthermore, we aim to update the template database optimally by introducing an additional time-variant forgetting factor parameter, which provides a balance between adaptivity and stability of the learning process automatically. Moreover, we enhanced the single-channel noise estimation system to be compatible with the multi-channel robot audition framework so that ego noise can be eliminated from all signals stemming from multiple sound sources respectively. We demonstrate that the proposed system allows the robot to have the ability of online template learning as well as a high performance of noise estimation and suppression for multiple sound sources.