Hybrid active noise cancellation filter adaptation

An apparatus for hybrid active noise control (ANC) filter adaptation, the apparatus comprising:

• a hybrid adaptive active noise control unit (HAANCU) configured to receive a first reference noise signal from a reference microphone and a first error signal from an error microphone and provide an output anti-noise signal to an ear speaker, wherein the HAANCU is operated at a first sampling rate;
• a decimator configured to decimate the first reference noise signal and the first error signal to obtain a second reference noise signal and a second error signal at a second sampling rate lower than the first sampling rate;
• an adaptive hybrid ANC training unit (AHANCTU) coupled to the decimator, operated at the second sampling rate, and comprising:
• a wide-band (WB) noise cancellation filter configured to generate a first anti-noise signal from the second reference noise signal;
• a narrow-band (NB) noise cancellation filter configured to generate a second anti-noise signal from the second error signal and the first anti-noise signal;
• and
• at least one feedback filter configured to provide a feedback signal to the WB noise cancellation filter and the NB noise cancellation filter for training of coefficients of the WB noise cancellation filter and the NB noise cancellation filter based on combining the first anti-noise signal, the second anti-noise signal, and an audio signal for playback via the ear speaker;
• and
• a rate conversion unit coupled to the AHANCTU and configured to up-sample the trained coefficients of the WB noise cancellation filter and the NB noise cancellation filter,
• wherein the providing the output anti-noise signal to the ear speaker by the HAANCU is based on receiving updating of the up-sampled and trained coefficients of the WB noise cancellation filter and the NB noise cancellation filter from the rate conversion unit.