Parametric study of loudspeaker spacing in an active noise control headrest system with head-tracking

The integration of head-tracking can improve the performance of active noise control headrest systems, by enabling a reduction in the mismatch between the plant model used by the controller and the physical plant response to be realised. However, the performance may still be limited due to constraints on the resolution of head-tracking and previous work has shown that the robustness of the system then depends on both the initial head position and the direction of head movement. This paper builds on this previous work to explore how the spacing between the two loudspeakers used in the headrest influences the effective controller performance over the spatial region where the head position is tracked. It is shown, through numerical simulations, that a trade-off can be observed between the controller robustness and the spatial extent over which effective control is achieved. These findings may be used to inform the robust design of an active headrest system with head-tracking.