US 11,942,068 B2
Adaptive active noise control system with unstable state handling and associated method
Chao-Ling Hsu, Hsinchu County (TW); and Li-Wen Chi, Hsinchu County (TW)
Assigned to Airoha Technology Corp., Hsinchu (TW)
Filed by Airoha Technology Corp., Hsinchu (TW)
Filed on Mar. 17, 2022, as Appl. No. 17/696,901.
Prior Publication US 2023/0298559 A1, Sep. 21, 2023
Int. Cl. G10K 11/178 (2006.01)
CPC G10K 11/17854 (2018.01) [G10K 11/17815 (2018.01); G10K 11/17823 (2018.01); G10K 11/17825 (2018.01); G10K 11/17881 (2018.01); G10K 2210/3026 (2013.01); G10K 2210/3027 (2013.01); G10K 2210/3028 (2013.01); G10K 2210/3044 (2013.01)] 20 Claims
OG exemplary drawing
 
1. An adaptive active noise control (ANC) system comprising:
an ANC circuit, arranged to generate an anti-noise signal for noise reduction, wherein the ANC circuit comprises at least one adaptive filter; and
a control circuit, arranged to receive a first input signal derived from a reference signal output by a reference microphone that picks up ambient noise, receive a second input signal derived from an error signal output by an error microphone that picks up remnant noise resulting from the noise reduction, and perform a transfer function variation detection based on the first input signal and the second input signal to control the at least one adaptive filter, wherein the transfer function variation detection is arranged to detect transfer function variation of a path between the first input signal and the second input signal, and the control circuit comprises:
a detection circuit, arranged to deal with the transfer function variation detection, wherein the detection circuit comprises:
a transfer function estimation circuit, arranged to estimate a previous transfer function of the path between the first input signal and the second input signal and a current transfer function of the path between the first input signal and the second input signal;
a path change degree evaluation circuit, arranged to determine a path change degree value according to difference between the previous transfer function and the current transfer function; and
a comparison circuit, arranged to compare the path change degree value with a pre-defined threshold to generate a comparison result, set a flag signal according the comparison result, and output the flag signal to the at least one adaptive filter;
wherein the at least one adaptive filter is controlled by the flag signal.