On the secondary path of headset active noise cancellation systems

Active noise cancellation (ANC) technologies have been successfully applied in headsets to reduce ambient noise in the ear canal. The performance of such a technology depends on the characteristics of the secondary path (SP). In this paper, two different systems are studied: one system utilizes a moving-coil speaker as the secondary source and forms a closed cavity over the ear, while the other one uses a balanced-armature receiver inside the ear canal as the secondary source. The differences in the SP responses of these two systems are investigated both experimentally and theoretically. The implications for designing an effective ANC solution will be discussed based on numerical simulations.