Feedback Acoustic Noise Control with Faust on FPGA: Application to Noise Reduction in Headphones

This work studies the feedback Active Noise Control (ANC) in a headphone with a digital filter implemented on a FPGA instead of an analog filter, in the context of a pedagogical practice bench. The digital approach allows greater flexibility in setting the feedback ANC filter but brings an additional latency that can compromise the ANC efficiency. The principle of feedback ANC in headphones is reviewed and the choice of a biquadratic filter as a feedback ANC filter is argued. The digital filter is programmed in the FAUST language and compiled on a FPGA platform. An experimental validation is carried out to compare the attenuation performance between the digital and analog biquadratic filters. The results show similar or even better low frequency attenuation for some configurations of the digital biquadratic filter compared to the analog filter. Finally, a digital filter cascading two biquads is studied and shows a bandwidth broadening where the ANC is effective.