Active noise control system

Patent metadata

Field	Value
Publication number	US-12394403-B2
Application number	US-202318196008-A
Country	US
Kind code	B2
Filing date	May 11, 2023
Priority date	May 18, 2022
Publication date	Aug 19, 2025
Grant date	Aug 19, 2025

Abstract

An active noise control system includes an error adder that generates an error signal by adding an output of a left-seat left microphone and an output of a left-seat right microphone, an adaptive filter that generates a noise canceling sound from a reference signal by performing an adaptive operation using the reference signal and the error signal, a left channel gain adjustment section that adjusts a gain of the noise canceling sound to be output to a left-seat left speaker, and a right channel gain adjustment section that adjusts a gain of the noise canceling sound to be output to the left-seat right speaker. A ratio between the gains of the left channel gain adjustment section and the right channel gain adjustment section matches a ratio between loudness levels of noise transmitted to the output of the left-seat left microphone and the output of the left-seat right microphone.

First claim

The invention claimed is:

1. An active noise control system that reduces noise, the active noise control system comprising:
a first microphone that is disposed in a position displaced in a first direction relative to a user;
a second microphone that is disposed in a position displaced in a second direction relative to the user;
a first speaker configured to emit sound toward an area around the position where the first microphone is disposed;
a second speaker configured to emit sound toward an area around the position where the second microphone is disposed;
an error signal generator configured to generate an addition signal by adding an output of the first microphone and an output of the second microphone;
an adaptive filter configured to perform an adaptive operation of minimizing an error using a signal correlated with the noise as a reference signal and the addition signal as the error so as to generate a noise canceling sound to be output from the first and second speakers; and
a gain adjustment section configured to adjust a ratio between a loudness level of a first noise canceling sound which is the noise canceling sound to be output from the first speaker and a loudness level of a second noise canceling sound which is the noise canceling sound to be output from the second speaker;
wherein the gain adjustment section is configured to perform the adjustment so that the ratio of the loudness level of the second noise canceling sound to the loudness level of the first noise canceling sound matches a ratio of a loudness level of noise transmitted from a noise source of the noise to the second microphone to a loudness level of noise transmitted from the noise source of the noise to the first microphone.

2. The active noise control system according to claim 1 , wherein:
when one of a position near a left ear of the user or a position near a right ear of the user is determined as a first position and the other is determined as a second position, the first microphone is disposed in the first position and the second microphone is disposed in the second position.

3. The active noise control system according to claim 2 , wherein:
when one of left or right seats of a car is determined as a first seat and the other is determined as a second seat, the user seats on the first seat, and
the noise is sound output from a loudspeaker near the second seat to an occupant of the second seat.

4. An active noise control system that reduces noise, the active noise control system comprising:
a first microphone that is disposed in a position displaced in a first direction relative to a user;
a second microphone that is disposed in a position displaced in a second direction relative to the user;
a first speaker configured to emit sound toward an area around the position where the first microphone is disposed;
a second speaker configured to emit sound toward an area around the position where the second microphone is disposed;
an error signal generator configured to generate an addition signal by adding an output of the first microphone and an output of the second microphone;
an adaptive filter configured to perform an adaptive operation of minimizing an error using a signal correlated with the noise as a reference signal and the addition signal as the error so as to generate a noise canceling sound to be output from the first and second speakers; and
a delay adjustment section configured to adjust a delay time between a first noise canceling sound which is the noise canceling sound output from the first speaker and a second noise canceling sound which is the noise canceling sound output from the second speaker;
wherein the delay adjustment section is configured to perform the adjustment such that a delay time of the second noise canceling sound relative to the first noise canceling sound matches a delay time of noise transmitted from a noise source of noise to the second microphone relative to the noise transmitted from the noise source of the noise to the first microphone.

5. The active noise control system according to claim 4 , further comprising:
a gain adjustment section configured to adjust a ratio between a loudness level of a first noise canceling sound which is the noise canceling sound to be output from the first speaker and a loudness level of a second noise canceling sound which is the noise canceling sound to be output from the second speaker;
wherein the gain adjustment section is configured to perform the adjustment such that the ratio of the loudness level of the second noise canceling sound to the loudness level of the first noise canceling sound matches a ratio of a loudness level of noise transmitted from a noise source of the noise to the second microphone to a loudness level of noise transmitted from the noise source of the noise to the first microphone.

6. The active noise control system according to claim 5 , wherein:
when one of a position near a left ear of the user or a position near a right ear of the user is determined as a first position and the other is determined as a second position, the first microphone is disposed in the first position and the second microphone is disposed in the second position.

7. The active noise control system according to claim 6 , wherein:
when one of left or right seats of a car is determined as a first seat and the other is determined as a second seat, the user seats on the first seat, and
the noise is sound output from a loudspeaker near the second seat to an occupant of the second seat.

8. The active noise control system according to claim 4 , wherein:
when one of a position near a left ear of the user or a position near a right ear of the user is determined as a first position and the other is determined as a second position, the first microphone is disposed in the first position and the second microphone is disposed in the second position.

Assignees

• Alps Alpine Co Ltd

Inventors

• Tachi Ryosuke
• Tanno Keita

Classifications

• G10K2210/3221

  Headrests, seats or the like, for personal ANC systems · CPC title

• G10K2210/3056

  Variable gain · CPC title

• G10K2210/3055

  Transfer function of the acoustic system · CPC title

• G10K2210/3046

  Multiple acoustic inputs, multiple acoustic outputs · CPC title

• G10K2210/3044

  Phase shift, e.g. complex envelope processing · CPC title