Primary Path Estimator Based on Individual Secondary Path for ANC Headphones

Abstract

Active noise cancellation (ANC) technology is a valuable asset for hearables. For a well performing and robust ANC system precise knowledge of the relevant acoustic paths is vital. It is feasible to individually measure the user’s secondary path by using the inner loudspeaker and microphone that are already built in into most ANC headphones. For measuring the primary path, however, an external loudspeaker as well as a suitable environment for acoustic measurements is required.We exploit that changes in the primary and secondary path appear jointly, based on the headphone fitting and the physiology of the user’s ear. In this contribution, we propose an estimator for the individual primary path based on a measurement of the individual secondary path. We evaluate the estimator by comparing the ANC performance to conventional fixed filter design methods for a large data set of real acoustic paths of an in-ear ANC headphone.