Effect of tracking resolution and loudspeaker arrangements on a headtracked active headrest noise control system

Head-tracking techniques offer the potential of improving the performance of local active noise control headrest systems during head movements. However, the effectiveness of head-tracked local active noise control can be limited by various aspects of the headrest design. This paper presents a thorough investigation into how head-tracking accuracy influences the control performance for both translational and yaw rotational head movements and, in addition, how this is affected by the geometry of the headrest control loudspeakers. The presented results highlight a notable difference in the attenuation performance achieved at the two ears when modelling errors exist between the physical plant response and the plant model utilised by the controller, which arise due to the accuracy of the head-tracking. It is demonstrated that the mismatch in performance between the two ears is influenced by the initial head position, the direction of head movements, and the layout of the headrest control loudspeakers. In the presence of plant modelling errors, the presented results reveal a trade-off between the balance in attenuation performance at the two ears and the spatial extent over which effective control is achieved. The presented insights can be utilised to help design local active noise control headrest systems with head-tracking that are well-suited to their intended application.