US 12,277,922 B2
Cancel filter coefficient selecting apparatus, cancel filter coefficient selecting method, and program
Kazunori Kobayashi, Tokyo (JP); Noriyoshi Kamado, Tokyo (JP); and Masahiro Fukui, Tokyo (JP)
Assigned to NIPPON TELEGRAPH AND TELEPHONE CORPORATION, Tokyo (JP)
Appl. No. 17/924,908
Filed by NIPPON TELEGRAPH AND TELEPHONE CORPORATION, Tokyo (JP)
PCT Filed Dec. 14, 2020, PCT No. PCT/JP2020/046498
§ 371(c)(1), (2) Date Nov. 11, 2022,
PCT Pub. No. WO2021/234987, PCT Pub. Date Nov. 25, 2021.
Claims priority of application No. PCT/JP2020/019629 (WO), filed on May 18, 2020.
Prior Publication US 2023/0197054 A1, Jun. 22, 2023
Int. Cl. G10K 11/178 (2006.01); G06V 20/59 (2022.01); G06V 40/16 (2022.01)
CPC G10K 11/17881 (2018.01) [G06V 20/593 (2022.01); G06V 40/172 (2022.01); G10K 11/17853 (2018.01)] 3 Claims
OG exemplary drawing
 
1. A cancellation filter coefficient selection apparatus,
wherein a signal output by a reference microphone for collecting noise in a predetermined space is used as a reference signal, a signal output by an error microphone for collecting sound at a position where quiet is desired is used as an error signal, and a signal generated by filtering the reference signal using a cancellation filter coefficient selected immediately previously is used as a cancellation signal,
the cancellation filter coefficient selection apparatus comprising:
a recording circuitry configured to record cancellation filter coefficients;
a first path filter configured to generate a filtered cancellation signal based on the cancellation signal through filtering using a path filter coefficient indicating an acoustic characteristic of a path from a speaker for emitting sound based on the cancellation signal to the error microphone;
a subtraction circuitry configured to generate an estimated error signal by subtracting the filtered cancellation signal from the error signal; and
a cancellation filter coefficient selection circuitry configured to use the reference signal and the estimated error signal to select a cancellation filter coefficient for best cancelling noise from among the cancellation filter coefficients recorded in the recording circuitry,
wherein the cancellation filter coefficient selection circuitry includes:
a second path filter configured to generate a filtered reference signal based on the reference signal through filtering using a path filter coefficient indicating an acoustic characteristic of a path from the speaker to the error microphone:
an average level calculation circuitry configured to calculate, for each of the cancellation filter coefficients recorded in the recording circuitry, an average level of a residual signal obtained by adding the estimated error signal and a signal generated based on the filtered reference signal through filtering using the cancellation filter coefficient; and
a minimum cancellation filter coefficient selection circuitry configured to, from among the cancellation filter coefficients recorded in the recording circuitry, select a cancellation filter coefficient according to which the average level of the residual signal is minimized as a cancellation filter coefficient for best cancelling noise.