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Active headrest with moving error microphone for real-time adaptive noise control

Design and implementation of active headrest are having challenges as the performance of noise reduction at the ear reduces due to head movement. In this paper, an active headrest is implemented using two secondary loudspeakers and two error microphones using a multi-channel active noise control (ANC) algorithm running on a dSpace dS1104 platform. The performance of an active headrest was studied for head movement. It was previously known that when the head is moved, the secondary path in ANC is changed and hence the ANC performance is degraded. However, through experimental evaluation, it is established in this paper that the secondary path change has hardly any effect on ANC performance if the error microphones are also moved along with the head. Therefore, it is proposed that a head-tracking system along with a motorized system to move the two error microphones to the ear location will make the active headrest robust and equally effective at every head position.