US Patent 11189261 Hybrid active noise control system

An apparatus for canceling noise at an ear speaker includes a wideband active noise cancellation filter having a first bandwidth and configured to generate a wideband anti-noise signal from a received reference noise signal, a narrowband active noise cancellation filter having a second bandwidth smaller than the first bandwidth and configured to generate a narrowband anti-noise signal from an error noise signal, a filter between the ear speaker and an error microphone and configured to generate a feedback noise signal, and a controller. The controller is configured to eliminate the error noise signal by modifying coefficients of the wideband active noise cancellation filter and the narrowband active noise cancellation filter in response to the wideband anti-noise signal, the narrowband anti-noise signal, and the feedback noise signal.