Active noise control incorporating external wireless acoustic sensors.

Wireless devices with one or more acoustic sensors (e.g., smartphones and laptops) have become ubiquitous in our daily life. Their distribution in the environment can be beneficially exploited for active noise control (ANC) systems to sample the sound field with a higher spatial resolution. In this study, an ANC system incorporating external wireless acoustic sensors (WASs) is introduced. Unlike conventional Wiener/adaptive filters, the filters are designed after taking the communication delay of WASs into account. Specifically, to achieve real-time processing, the filters are determined by minimizing the error signal power while forcing partial filter coefficients that correspond to WAS signals unavailable in time at the ANC controller to zero. Under this criterion, both optimal and adaptive filters are derived, where the former provides the theoretical bound on performance, while the latter supports real-time noise reduction. Due to the joint impact of communication and acoustic propagation delays, some WASs provide limited benefit to the local ANC system and may even degrade the adaptive filtering performance. To this end, the theoretical performance gain offered by WASs is analyzed, from which the most informative WASs are selected to improve computational efficiency. Simulation and real-world experiments show the validity of the proposed methods.