# US 2010/0166202 A1 · Noise reduction device

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- Number: US 2010/0166202 A1
- Document ID: US20100166202A1
- Status: Published application
- Kind: A1
- Application number: 12/641,732
- Filed: 2009-12-18
- Published: 2010-07-01
- Earliest claimed: 2008-12-26
- Assignees: Panasonic Corporation
- Inventors: Keiji Mori; Hiroyuki Kano; Tsuyoshi Maeda; Yoshifumi Asao
- Web page: https://patentgrep.com/patent/US20100166202A1

## CPC

- G10K 11/17817: {between the output signals and the error signals, i.e. secondary path}
- G10K 11/17825: {Error signals}
- G10K 11/17854: {the filter being an adaptive filter}
- G10K 11/17855: {for improving speed or power requirements}
- G10K 11/17881: {the reference signal being an acoustic signal, e.g. recorded with a microphone}
- G10K 2210/1281: Aircraft, e.g. spacecraft, airplane or helicopter
- G10K 2210/3027: Feedforward
- G10K 2210/3055: Transfer function of the acoustic system
- G10K 2210/3221: Headrests, seats or the like, for personal ANC systems
- G10K: SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR

## Abstract

A noise control device includes the following structural elements. A signal memory records both of a noise signal supplied from a noise microphone and an error signal supplied from an error microphone. A filter coefficient calculator calculates a fixed filter coefficient of a control filter by using data recorded in the signal memory. A filter coefficient renewing section renews, at a given timing, a filter coefficient set at a fixed filter in a control filter to a filter coefficient read out from the filter coefficient calculator.

## Claims

### Claim 1

A noise control device for reducing a given noise arriving at a control point by radiating a control sound toward the control point, the noise control device comprising:
a controlling noise detector for detecting a given coming-noise and outputting a controlling noise signal;
a control filter for processing the controlling noise signal supplied from the controlling noise detector by using a fixed filter coefficient set in advance, and thereby outputting a control signal;
a control speaker radiating a control sound based on the control signal supplied from the control filter for reducing the given noise arriving at the control point;
an error detector placed at the control point for detecting an error signal between the noise and the control sound that is supplied from the control speaker;
a signal memory for storing the controlling noise signal supplied from the controlling noise detector and an error signal detected by the error detector;
a filter coefficient calculator for calculating a filter coefficient by using the controlling noise signal and the error signal both stored in the signal memory; and
a filter coefficient renewing section for renewing, at a given timing, a fixed filter coefficient set at the control filter to a filter coefficient calculated by the filter coefficient calculator.

### Claim 2 (depends on 1)

The noise control device of claim 1 further comprising:
an effect determiner for determining a signal level of the error signal detected by the error detector,
wherein a start of storing operation of the signal memory and a halt of operation of the control filter are controlled based on a determination result of the effect determiner.

### Claim 3 (depends on 1)

The noise control device of claim 1, wherein the filter coefficient calculator includes:
an adaptive filter for signal-processing the controlling noise signal stored in the signal memory;
an acoustic filter for signal-processing an output from the adaptive filter; and
an adder for adding an output signal from the acoustic filter to the error signal stored in the signal memory,
wherein a transfer function from the control speaker to the error detector is set as a filter coefficient at the acoustic filter, and
wherein the adaptive filter renews the filter coefficient such that an adding result supplied from the adder can be minimized as an error signal to be used for renewing a filter coefficient.

### Claim 4 (depends on 1, 3)

The noise control device any one of claim 1-claim 3 further comprising:
a filter coefficient memory for storing a filter coefficient lastly renewed by the filter coefficient renewing section, wherein the adaptive filter uses a filter coefficient stored in the filter coefficient memory as an initial parameter.

### Claim 5 (depends on 4)

The noise control device of claim 4, wherein the filter coefficient memory can be replaceable as a unit.