Robust Sound Zone Filters for Synchronization Errors

Low-frequency sound zones can be created by controlling the sound pressure using loudspeakers distributed throughout the room. When transmitting filtered signals using wireless communication technology, the performance of the low-frequency sound zone system is sensitive to potential synchronization errors among distributed loudspeakers. Recent experiments have shown that a delay of 0.83 ms in only one loudspeaker will lead to a 3-15 dB decrease in the mean acoustic contrast, depending on which loudspeaker is influenced. In this paper, we propose a set of robust filters for the sound zone system by incorporating information about the expected synchronization errors in playback time into the design to increase the robustness towards such errors. With such robust filters, the sound zone system can still achieve comparative performance under more relaxed synchronization requirements among playback from the wireless woofers. The performance of the proposed robust filters is evaluated in a simulated sound zone system with loudspeakers surrounding two control regions. The mean contrasts under various situations for the robust filters are shown to outperform the original filters.