JPH05313672A - Noise controller - Google Patents

Abstract

PURPOSE:To improve elimination characteristics corresponding to variation in noise frequency. CONSTITUTION:The noise controller that eliminates a noise by outputting a sound wave which is opposite in phase and equal in sound pressure to the noise, is provided with an adaptive filter 123 which automatically adjusts a filter coefficient and generates the opposite-phase compensation signal with equal sound pressure, a filter coefficient updating means 124 which generates a filter coefficient updated with a noise signal and an error signal, a transfer characteristic simulating means 125 which corrects the input noise signal of the filter coefficient updating means 124 with characteristics obtained by simulating transfer characteristics from the adaptive filter 123 to the generation of the error signal, a frequency detecting means 121 which detects a noise frequency distribution, and a variable band filter 122 which optionally sets the passing frequency band of the noise signal according to the noise frequency distribution and controls input signals to the adaptive filter 123 and transfer characteristic simulating means 125.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise control device for eliminating noise by outputting a signal of noise and anti-phase equal sound pressure from a speaker, and in particular, the present invention improves the elimination characteristic in response to changes in noise frequency. The purpose is to let.

[0002]

2. Description of the Related Art Conventionally, a passive muffling device such as a muffler has been used to reduce noise generated from an internal combustion engine, etc., but improvements have been made in terms of size, muffling characteristics and the like. In contrast, the noise generated from the sound source and the opposite phase
An active noise control device has been proposed which outputs a compensation sound of equal sound pressure from a speaker and cancels noise. By the way, the frequency characteristic or stability of the active noise control device itself is not sufficient, and its practical application has been delayed. However, as a result of the recent development of signal processing technology using digital circuits and expansion of the frequency range to be handled, many practical noise control devices have been proposed (for example, Japanese Patent Laid-Open No. 63-311396).

This is because a noise source microphone installed upstream of the duct detects the noise, and a signal processing circuit outputs a signal having a phase opposite to that of the noise and equal sound pressure from a speaker installed downstream of the duct. This is a so-called two-microphone / one-speaker type active noise control device in which a feedback system for detecting and feeding back by a microphone for a sound deadening point is combined with a feedforward system.

[0004]

By the way, as a signal processing technique using a digital circuit for a noise control device, D
SP (Digital Signal Processor) is used, DSP
Is configured with an adaptive filter. However, when the frequency of noise changes variously, there is a problem that the scale of the adaptive filter becomes large and the convergence time thereof becomes long.

Therefore, in view of the above problems, it is an object of the present invention to provide a noise control device capable of improving the erasing characteristic even when the noise frequency changes.

[0006]

In order to solve the above problems, the present invention inputs a noise signal from a noise source (1),
A speaker (4) for outputting sound waves of equal sound pressure and opposite phase to the noise
And a microphone (8) for detecting an error signal generated by canceling noise by the speaker (4), an adaptive filter, filter coefficient updating means,
A transfer characteristic simulating means, a frequency detecting means and a variable band filter are provided.

The adaptive filter automatically adjusts the filter coefficient to form a compensating signal of anti-phase equal sound pressure. The filter coefficient updating means forms the filter coefficient updated by the noise signal and the error signal. The transfer characteristic simulating means corrects the input noise signal of the filter coefficient updating means by a characteristic simulating the transfer characteristic from the adaptive filter to forming the error signal.

The frequency detecting means detects a noise frequency distribution from the noise source. The variable band filter, by the frequency distribution detected by the frequency detecting means,
The pass frequency band of the noise signal is arbitrarily set, and the input signal of the adaptive filter and the transfer characteristic simulating means is controlled.

[0009]

According to the noise control apparatus of the present invention, the filter coefficient is automatically adjusted by the adaptive filter to form the compensating signal of the anti-phase equal sound pressure. The filter coefficient updating means forms the filter coefficient updated based on the noise signal and the error signal. The input noise signal of the filter coefficient updating means is corrected by the transfer characteristic simulating means by a characteristic simulating the transfer characteristic from the adaptive filter to forming the error signal. A noise frequency distribution from the noise source is detected by the frequency detecting means. The variable band filter arbitrarily sets the pass frequency band of the noise signal based on the frequency distribution detected by the frequency detecting means, and controls the input signals of the adaptive filter and the transfer characteristic simulating means. Therefore, it is possible to pass the noise signal only in the desired frequency band and improve the erasing characteristics.
A desired erasing characteristic can be obtained, and an increase in scale of the adaptive filter can be suppressed.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a noise control device which is a premise of the first embodiment of the present invention. The noise control device of the present figure physically muffles noise from a noise source 1 of an engine of a vehicle or the like, and eliminates residual noise in a muffling space 3 near a tail pipe at an exit from a muffler 2 having a constant transfer characteristic. A speaker 4 installed for silencing, a power amplifier 5 for driving the speaker 4, and a low-pass filter 6 installed before the power amplifier 5 for removing high frequency components of an analog signal.
And a D / A converter 7 (Digital to Analyst) for converting a digital signal into an analog signal for the low-pass filter 6.
og Converter), a microphone 8 installed near the speaker 4 for detecting an error signal, an amplifier 9 for amplifying an electric signal of the microphone 8, and a low frequency band for removing a high frequency component of the amplified signal of the amplifier 9. Pass filter 10
And an A / D converter 11 (Analog to Digita) for converting an analog signal of the low-pass filter 10 into a digital signal.
lConverter) and a signal such as an engine speed as a noise source signal of the noise source 1 are input to the A / D converter 11
From the D / A so that the error signal at the silence point is minimized.
A digital signal processing device 12 (Digital Signal Processo) for forming a compensation signal for canceling noise in the converter 6
r), a RAM 13 (Random Access Memory) for storing the program of the digital signal processing device 12, and the RA
The M13 is provided with a central processing unit 14 for transferring a program from a ROM 15 (Read Only Memory) and temporarily storing the program in the RAM 16 for that purpose.

FIG. 2 is a diagram showing the configuration of the digital signal processing apparatus shown in FIG. The digital signal processing device shown in this figure inputs the rotation speed of the engine, which is the noise source 1, and detects the frequency of noise, and the frequency detection means 121 that inputs the rotation speed of the engine and outputs the frequency from the frequency detection means 121. Variable band filter 12 that changes the frequency band according to information
2, an adaptive filter 123 that inputs a signal of a frequency selected by the variable band filter 122 and automatically updates a filter coefficient to form a noise compensation signal, and an error signal detected by the microphone 8 Filter coefficient updating means 124 for forming the filter coefficient of the adaptive filter 123 from the input signal to the adaptive filter 123, and means for simulating the transfer characteristic of the signal from the output of the adaptive filter 123 to the filter coefficient updating means 124. And a transfer characteristic simulating means 125 for inputting an input signal to the adaptive filter 123 to form a simulated signal and supplying the simulated signal to the filter coefficient updating means 124. Here, the transfer characteristic from the adaptive filter 123 to the microphone 8 is Hd,
Assuming that the transfer characteristic from the microphone 8 to the filter coefficient updating means 124 is Hm, the simulated transfer characteristic Hd1 of the transfer characteristic simulating means 125 is Hd1 = Hd.Hm (1).

FIG. 3 is a diagram showing the configuration of the frequency detecting means 121 of FIG. The frequency detection means 121 shown in this figure is
A plurality of band-pass filters 1211-1, 1211-2, ..., 12 for inputting the engine speed signal Sr from the noise source 1
11-n, a plurality of level forming means 1212-1, 1212-2, ..., 1212-n connected to each of the plurality of bandpass filters 1211 and averaging the output levels thereof, and the level forming means 1212. Maximum frequency band detecting means 12 for comparing the levels and detecting the maximum level frequency band
13 and 13. Note that each of the plurality of bandpass filters 1211 may be configured by a secondary digital filter described below.

FIG. 4 is a diagram showing the configuration of the variable band filter of FIG. The variable bandpass filter 122 shown in the figure is a second-order digital filter, which delays an input signal by a time of one sampling period and outputs a first-order delayed signal, and a delay means 1221 which further delays the output and then Delay means 1222 for outputting the next delay signal and delay means 1 for delaying the output signal and outputting it as a primary feedback signal
223, delay means 1224 for further delaying and outputting as a secondary feedback signal, multiplying means 1225 for multiplying the input signal by a predetermined coefficient a0, and outputting and a predetermined coefficient a1 for the primary delay signal. Multiplying means 1226 for multiplying and outputting, multiplying means 1227 for multiplying and outputting the secondary delay signal by a predetermined coefficient a2, and multiplying means for multiplying and outputting the primary feedback signal by a predetermined coefficient b1. 1228 and a multiplication means 122 for multiplying the secondary feedback signal by a predetermined coefficient b2 and outputting the result.
9 and multiplication means 1225, 1226, 1227, 122
8 and 1229 are all added to add as an output signal. Coefficients a0 and a1 of the multiplication means
, A2, b1, b2 of various noise frequency bands are stored in the RAM 13, and a constant of a predetermined frequency band is set in the multiplying means by the frequency distribution detected by the frequency detecting means 121.

FIG. 5 is a diagram showing the configuration of the adaptive filter of FIG. The adaptive filter 123 shown in this figure is a non-recursive FIR (Finite Impulse Response), and receives a signal from the variable band filter 122 and sequentially delays by a delay time τ. -2,
, 1231- (k-1), the input signal, and the filter coefficients C0 (n) and C, which will be described later, in the output from each delay means 1231.
Multiplying means 1232 for multiplying 1 (n), C2 (n), ..., Ck (n)
-1,1232-2, 1232-3, ..., 1232-k
And the output of each multiplication means 1232 are added to obtain the compensation signal Sc
, 1233, ...
1233- (k-1).

FIG. 6 shows the filter coefficient updating means (LS) of FIG.
It is a figure which shows the structure of M). The filter coefficient updating means 124 shown in the figure is the error signal Sm from the A / D converter 11.
1 is a delay means 1242-1, 1242-2, ..., 1 which sequentially delays the signal from the multiplication means 1241 for multiplying (n) by a constant constant α and the transfer characteristic simulation means 125 with a delay time τ.
242- (k-1) and the output signal of the multiplying means 1241 are divided by the input signal from the transfer characteristic simulating means 125 and the output signal of each delaying means 1242 to normalize and normalize them. 2, ..., 1243- (k-
1) and the outputs of the respective normalizations and the signals described later are added to the filter coefficients C0 (n), C1 (n), C2 (n), ...
Addition means 1244-1, 1244-2, ..., 1244-k for forming Ck (n) and outputting it to each of the multiplication means 1232.
And delay means 1245 for delaying the output of each adding means 1244 by delay time τ and adding to each adding means 1244.
, 1245-2, ..., 1245-k.

With the above configuration, the filter coefficient for the multiplication means 1232 is formed as follows. In FIG. 5, assuming that the input data to the adaptive filter 123 is q (n), the output data of each delay means 1231 is q (n-1), q.
(n-2), q (n-3), ..., Q (n-k + 1). Here, assuming that the filter coefficients set in each multiplication means 1231 are C0 (n), C1 (n), C2 (n), C3 (n), ..., Ck (n), as described above. Output data Sc of adaptive filter 151
(n) is as follows.

Sc (n) = C0 (n) .q (n) + C1 (n) .q (n-1) + C2 (n) .q (n-2) + C3 (n) .q (n-3) +, ..., + Ck (n) · q (n-k + 1) (2) Next, in FIG. 6, from the A / D converter 11 to each multiplication means 1
One input data to 241 is Sm (n), and multiplication means 1
The coefficient updating constant as the other data to 241 is α,
The input data from the transfer characteristic simulating means 125 to the delay means 1242 is q (n) as in the above, and each delay means 1242 is
Output data of q (n-1), q (n-2), q (n-3), ..., q
It becomes (n-k + 1). Therefore, the output data from the adding means 1241 is output to the delaying means 124 by the normalizing means 1243.
It is normalized by the signal from 2 and is formed into the following filter coefficient by each addition means 1244 and delay means 1245.

Ck (n) = Ck (n-1) + (Sm (n) · α) / q (n + k-1), (k = 1 to k) (3) Thus, according to the present embodiment. For example, the frequency detecting means 121 detects the engine speed to specify the frequency of noise, and only the noise of the specified frequency passes through the variable band filter 122. Therefore, the adaptive filter 123 has a conventional structure. Since it is not necessary to process signals of all frequencies, that is, only the frequency band having a large influence has to be erased, the processing load is reduced and the erase characteristic can be improved.

FIG. 7 is a block diagram showing the arrangement of a digital signal processing apparatus according to the second embodiment of the present invention. The digital signal processing device 12 shown in this figure is obtained by replacing the variable band filter 122 shown in FIG. 2 with a plurality of variable band filters 131. The variable band filter 131 includes a plurality of band filters 132-1 and 132-1 for inputting the engine speed Sr.
2-2, ..., 132-n and the frequency detecting means 121.
The multiplication means 1 for varying the output level of each of the band-pass filters 132 according to the result of (1) to pass the noise of the desired frequency.
33-1, 133-2, ..., 133-n and the outputs of the respective multiplication means 133 are added, and the result is added to the adaptive filter 1
23, adding means 13 for outputting to transfer characteristic simulating means 125
Including 4 and.

FIG. 8 shows the characteristics of the bandpass filter according to this embodiment. This figure (a) shows the frequency spectrum of the signal input into each bandpass filter. On the other hand, this figure (b) shows the gain with respect to the frequency of each bandpass filter. The frequency detecting means 121 detects the frequency fm of the maximum peak from this figure (a) and selects the bandpass filter 132-1 (BPF1) corresponding to this figure (b), so the multiplication coefficient of the multiplying means 133-1. Is set to "1" and the other multiplying means is set to "0".

The detection of the frequency of the maximum peak has been described above for simplification of description, but it may be set so that only the desired detection frequency band is passed. FIG. 9 is a diagram showing the configuration of a digital signal processing apparatus according to the third embodiment of the present invention. In the digital signal processing device 12 shown in this figure, the variable band filter 122 of the first embodiment shown in FIG. 2 is provided before the input of the adaptive filter 123, but instead of this, the variable band filter 122 is used.
Is provided at the position of the input stage from the A / D converter 11 of the filter coefficient updating means 124 and at the position of the input stage from the transfer characteristic simulating means 125. The two variable band filters 122 are controlled by the frequency detecting means 121 in the same manner as described above.

According to the above equation (3), the filter coefficient updating means 124 uses the engine speed as an input signal for normalizing the error signal. Further, it is conceivable that the error signal detected by the microphone 8 also has the maximum frequency component of noise remaining. Therefore, the filter coefficient updating means 124 also extracts the component of the maximum frequency of noise by the variable band filter 122, configures the filter coefficient by the input signal and the error signal, and is most responsive to the maximum frequency. Therefore, the time required to converge to the optimum point of the filter coefficient can be shortened.

FIG. 10 is a diagram showing a digital signal processing apparatus 12 according to the fourth embodiment of the present invention. As a modification of the third embodiment, the digital signal processing device 12 shown in the figure has the variable band filter 122 replaced by the variable band filter 131 shown in FIG. 2, and has the same operation as that of the third embodiment. The effect is obtained. The above is the signal processing system of the feedforward system, but next, the configuration of the feedback system will be described.

FIG. 11 is a block diagram showing the arrangement of a digital signal processing apparatus according to the fifth embodiment of the present invention. The digital signal processing device 12 shown in the figure is an adaptive filter 123.
, A transfer characteristic simulating means 125 for forming a transfer simulating characteristic signal from the input signal of the adaptive filter 123, and an adaptive filter from the signal from the A / D converter 11 and the first transfer characteristic simulating means 125. Filter coefficient updating means 124 for forming the filter coefficient 123, and the adaptive filter 1
First transfer characteristic simulating means 125 provided on the output side of 23
The second transfer characteristic simulating means 126 similar to the above, and the difference between the signal from the second transfer characteristic simulating means 126 and the signal from the A / D converter 11 is calculated to reproduce the noise signal from the feedback signal. Difference signal calculation means 127, variable band filter 122 provided between the difference signal calculation means 127 and the adaptive filter 123, and frequency detection means 121 for detecting the maximum frequency of noise by the engine speed signal.
Including and

Assuming that the transfer characteristic from the noise source 1 to the sound deadening space 3 is Hnoise, the signal Sm0 detected by the microphone 8 in the sound deadening space 3 is Sm0 = Sn.Hnoise + Sc.Hd ... ( 4) Here, Sn is the noise signal of the noise source. The input signal Se of the adaptive filter 123 is: Se = Sm0.Hm-Sc.Hd1 = (Sn.Hnoise + Sc.Hd) .Hm-Sc.Hd.Hm (see formula (3)) = Sn.Hnoise.Hm + Sc .Multidot.Hd.multidot.Hm-Sc.multidot.Hd.multidot.Hm = Sn.multidot.Hnoise.multidot.Hm, and a signal similar to that obtained when the noise signal is detected by the microphone 8 is obtained.

This signal Se is the same as in the first embodiment.
It is processed by the frequency detection means 121 and the variable band filter 122, and for example, is processed only when the noise frequency becomes maximum. The feedforward systems of the second, third, and fourth embodiments may be feedback systems as in the above.

FIG. 12 is a diagram showing the configuration of a digital signal processing device 12 according to the sixth embodiment of the present invention. The digital signal processing device 12 shown in this figure is a combination of a feedforward system and a feedback system.
Is different from the configuration of the first
Variable band filter 128 and a second variable band filter 129 for inputting the reproduced signal from the difference signal calculation means 127.
And an adding means 130 for adding the output signals of the first and second variable band filters 128 and 129 and outputting the result to the adaptive filter 123, and the first and second variable band filters 128.
And the frequency detection means 121 for controlling the frequency bands of 129 to have complementary characteristics.

First and second variable band filters 128 and 1
Numeral 29 may be one which makes the coefficient of the multiplication means variable as in FIG. 4, or may be one which makes the multiplication coefficient of the variable multiplication means of the plurality of band-pass filters variable as shown in FIG. FIG. 13 is a diagram showing the characteristics of the variable band filter according to the sixth embodiment. The frequency detecting means 12 is shown in FIG.
This is the spectrum input to 1. In this case, assuming that a peak occurs at the frequency f1 as shown in this figure, the frequency detecting means 121 detects this and sets the gain of the first variable band filter 128 as shown in this figure (b). It is adjusted so that only the frequency f1 of the input signal of the engine speed is passed. On the other hand, the gain of the second variable frequency band filter 129 is adjusted so that only the frequency of the signal of the difference signal calculation means 127 is not passed as shown in FIG.

Therefore, the fundamental wave passes the input of the feedforward system through the first variable band filter 128,
Other frequencies, that is, harmonics, are input to the adaptive filter 123 after passing the input of the feedback system through the second variable frequency band filter 129. Therefore, the muffling effect can be obtained even when the noise frequency other than the fundamental wave is generated in the muffler 2.

[0030]

As described above, according to the present invention, the pass frequency band of the noise signal is arbitrarily selected according to the detected frequency distribution, and only the selected signal is processed by the adaptive filter. The erasing characteristic can be improved and the desired erasing characteristic can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a noise control device which is a premise of a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of the digital signal processing device of FIG.

FIG. 3 is a diagram showing a configuration of frequency detection means 121 of FIG.

FIG. 4 is a diagram showing a configuration of a variable band filter in FIG.

5 is a diagram showing the configuration of the adaptive filter shown in FIG. 2;

FIG. 6 is a diagram showing a configuration of a filter coefficient updating unit (LSM) shown in FIG.

FIG. 7 is a diagram showing a configuration of a digital signal processing device according to a second embodiment of the present invention.

FIG. 8 is a diagram showing characteristics of a bandpass filter according to the present embodiment.

FIG. 9 is a diagram showing a configuration of a digital signal processing device according to a third embodiment of the present invention.

FIG. 10 is a diagram showing a digital signal processing device 12 according to a fourth embodiment of the present invention.

FIG. 11 is a diagram showing a configuration of a digital signal processing device according to a fifth exemplary embodiment of the present invention.

FIG. 12 is a diagram showing the configuration of a digital signal processing device 12 according to a sixth embodiment of the present invention.

FIG. 13 is a diagram showing characteristics of a variable band filter according to a sixth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Noise source 4 ... Speaker 8 ... Microphone 12 ... Digital signal processing device 121 ... Frequency detection means 122, 128, 129, 131 ... Variable band filter 123 ... Adaptive filter 124 ... Filter coefficient update means 125, 126 ... Transfer characteristic simulation Means 127 ... Difference signal calculation means 130 ... Addition means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiro Sakiyama 1-2-2 Goshodori, Hyogo-ku, Kobe, Hyogo Prefecture Inside Fujitsu Ten Limited

Claims (9)

[Claims] 1. A speaker (4) for outputting a sound wave of opposite phase equal sound pressure to noise from a noise source (1), and a microphone (for detecting an error signal generated by canceling the noise by the speaker (4)). And a adaptive filter (123) that automatically adjusts a filter coefficient to form a compensating signal of anti-phase equal sound pressure, and the noise signal is updated by a signal Sr from a noise source and an error signal. Filter coefficient updating means (12) for forming a filter coefficient
4) and the input noise source signal S of the filter coefficient updating means (124)
A transfer characteristic simulating means (125) for correcting r by a characteristic simulating the transfer characteristic from the adaptive filter (123) to forming the error signal, and a noise frequency distribution from the noise source (1). A frequency detecting unit (121) for detecting and a frequency distribution detected by the frequency detecting unit (121) are used to arbitrarily set a pass frequency band of a noise signal, and the adaptive filter (123) and transfer characteristic simulating unit ( And a variable band filter (122) for controlling the input signal of (125). 2. The variable band filter (122) comprises a plurality of band filters (132) for passing a frequency of a noise signal of the noise source (1) in a plurality of divisions, and the frequency detection means (121). It has variable multiplication means (133) for adjusting the output level of each of the plurality of filters (132) according to the detected frequency distribution, and addition means (134) for adding the output of each of the variable multiplication means (133). The noise control device according to claim 1. 3. The variable band filter (122) arbitrarily sets a pass frequency band according to the frequency distribution detected by the frequency detection means (121), and inputs it to the filter coefficient update means (124). The noise control device according to claim 1, wherein the noise source signal and the error signal are respectively controlled. 4. The variable bandpass filter (122) has a plurality of frequencies for passing the noise source signal of the noise source (1) divided into a plurality of frequencies in order to control the noise source signal and the error signal, respectively. A band filter (132), a variable multiplication means (133) for adjusting the output level of each of the plurality of filters (132) based on the frequency distribution detected by the frequency detection means (121), and each of the variable multiplication means ( The noise control device according to claim 3, further comprising an adding unit (134) for adding the outputs of the (133). 5. A noise signal from a noise source (1) is input,
A speaker (4) for outputting sound waves of equal sound pressure and opposite phase to the noise
And a microphone (8) for detecting an error signal generated by canceling noise by the speaker (4), in which a filter coefficient is automatically adjusted to form a compensating signal for anti-phase equal sound pressure. Filter (123), filter coefficient updating means (124) for forming the filter coefficient updated by the input signal and error signal of the adaptive filter, and an input noise signal of the filter coefficient updating means (124),
A first transfer characteristic simulating means (125) for correcting the output signal of the adaptive filter (123) by a characteristic simulating the transfer characteristic from the adaptive filter (123) to forming the error signal. Second transfer characteristic simulating means (126) for correcting with a characteristic simulating the transfer characteristic from the adaptive filter (123) to forming the error signal, and the output of the second transfer characteristic simulating means (126) A difference signal calculation means (127) for calculating a difference between a signal and the error signal to reproduce a noise signal, a frequency detection means (121) for detecting a noise frequency distribution from the noise source (1), and the frequency detection According to the frequency distribution detected by the means (121), the pass frequency band of the reproduced noise signal is arbitrarily set, and the difference signal calculation means (127) outputs the adaptive filter (1). 23) and transfer characteristic simulating means (125)
And a variable band filter (122) for controlling an input signal to the noise control device. 6. The variable bandpass filter (122) comprises a plurality of bandpass filters (132) for passing a frequency of a reproduced noise signal of the noise source (1) in a plurality of divisions, and the frequency detection means (121). A variable multiplication means (133) for adjusting the output level of each of the plurality of filters (132) and an addition means (134) for adding the output of each of the variable multiplication means (133) according to the frequency distribution detected by The noise control device according to claim 5, which has. 7. The variable band filter (122) arbitrarily sets a pass frequency band according to the frequency distribution detected by the frequency detection means (121), and inputs it to a filter coefficient updating means (124). The noise control device according to claim 5, wherein the noise signal and the error signal are controlled respectively. 8. The variable bandpass filter (122) divides the frequency of the reproduced noise signal of the noise source (1) into a plurality of parts to pass the divided noise signal in order to control the reproduced noise signal and the error signal, respectively. A band filter (132), a variable multiplication means (133) for adjusting the output level of each of the plurality of filters (132) based on the frequency distribution detected by the frequency detection means (121), and each of the variable multiplication means ( The noise control device according to claim 7, further comprising: an addition unit (134) for adding the outputs of (133). 9. A speaker (4) which inputs a noise source signal from a noise source (1) and outputs a sound wave having an antiphase equal sound pressure to the noise, and an error caused by eliminating the noise by the speaker (4). In a noise control device having a microphone (8) for detecting a signal, an adaptive filter (123) that automatically adjusts a filter coefficient to form a compensating signal for anti-phase equal sound pressure, and a noise source signal and an error signal are used. Filter coefficient updating means (124) for forming the filter coefficient to be updated
And the input noise signal of the filter coefficient updating means (124)
A first transfer characteristic simulating means (125) for correcting the output signal of the adaptive filter (123) by a characteristic simulating the transfer characteristic from the adaptive filter (123) to forming the error signal. Second transfer characteristic simulating means (126) for correcting with a characteristic simulating the transfer characteristic from the adaptive filter (123) to forming the error signal, and the output of the second transfer characteristic simulating means (126) A difference signal calculation means (127) for calculating a difference between a signal and the error signal to reproduce noise, a frequency detection means (121) for detecting a noise frequency distribution from the noise source (1), and the frequency detection means. A first variable band filter (128) that arbitrarily sets a pass frequency band based on the frequency distribution detected by (121), and a frequency variable detected by the frequency detecting means (121). The frequency distribution, a second variable frequency band filter is set to pass the frequency band of the reproduced noise signal to the set gain characteristic opposite of said first variable band-pass filter (128) (1
29), the output signals of the first variable band filter (128) and the second variable frequency band filter (129) are added to add the adaptive filter (123) and the first transfer characteristic simulating means (125). ) Adding means (13) for controlling the input signal to
0) and a noise control device.