Combined analog/digital broadband feedback ANC for headsets

Authors: Hauke Krüger, Thomas Schumacher, Marco Jeub, Peter Vary

Abstract:

In this paper a novel approach for improved broadband feedback ANC is presented which is based on the combination of classical non-adaptive and adap- tive feedback ANC techniques. The non-adaptive part is suitable to attenuate ambient noise at low frequencies whereas the adaptive part attenuates periodic components of the ambient noise at all frequencies. Compared to other approaches involving hybrid feedback ANC techniques, e.g., [1], in the proposed approach, the two ANC parts are decoupled which has the benefit to allow for independent design and optimization of both parts. The proposed technique yields a higher overall noise attenuation performance compared to a purely classical non-adaptive feedback or purely adaptive feedback ANC system. Also, it leads to a more comfortable perception of the residual ambient noise compared to currently available ANC headsets. In addition to that, the combination of both techniques is also beneficial for practical realizations since the adaptive feedback ANC stabilizes the overall system. With regard to low cost headset devices, a mixed analog-digital realization of the new approach is proposed which allows for the extension of existing purely classical analog feedback systems by simply adding a digital circuitry on top.