JP2564446B2 - Noise control device - Google Patents

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 of engine, motor and the like and anti-phase equal sound pressure from a speaker. In particular, the present invention relates to a component part of the noise control device. The purpose is to easily judge the failure of the above by checking the initial equalization.

[0002]

2. Description of the Related Art Conventionally, a passive muffler 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. On the other hand, 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 to cancel noise. By the way, the frequency characteristics or the stability of the active noise control device itself are not sufficient, and its practical use has been delayed. However, as a result of the recent development of signal processing technology for processing digital signals 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).

[0003]

By the way, in the conventional digital signal processing device of the noise control device, the FIR (Fini
te Impulse Response) type adaptive filter is used, and the filter coefficient Ck (n + 1) of this adaptive filter is
It is updated so that the convergence condition by the least squares is satisfied, and the update is performed by normalizing with the reference signal Se (n) considering the transfer characteristic of the noise system, for example, as shown in the following formula.

Ck (n + 1) = Ck (n) + α × Sm (n) / Te (n) (1) where Sm (n) is an error signal, α is a convergence coefficient, and k is a filter coefficient. Is a number. In this case, since the error signal Sm (n) is the result of receiving the transfer characteristic, it is necessary to correct the reference signal with the same transfer characteristic as the error signal Sm (n). Further, for the feedback system that forms the reference signal Se (n) as the noise reproduction signal from the error signal and the compensation signal from the adaptive filter, the compensation signal is corrected with the same transfer characteristic as the above Te (n ) Is obtained.

However, the determination of the transfer characteristic in this way is called the initial equalization of the noise control device. However, if the speaker, microphone, etc. constituting the noise control device breaks down or deteriorates, the initial equalization precision becomes extremely high. However, there is a problem that the noise becomes worse and the sufficient noise effect cannot be obtained.
Therefore, an object of the present invention is to provide a noise control device capable of early detection of deterioration of the initial equalization accuracy in view of the above problems.

[0006]

In order to solve the above problems, the present invention provides a noise control device for forming a compensating signal of noise and anti-phase equal sound pressure, an adaptive filter, a coefficient updating means, and a first embodiment .
And a second simulated transfer characteristic correcting means, a reference sound generating means and an initial equalization judging means. The adaptive filter is noisy
Input the reference signal of and make the filter coefficient variable automatically.
The compensation signal is output.

[0007] The coefficient updating means sets the opposite phase equal sound pressure and the
The residual sound generated by the noise interference is detected as an error signal and this error is detected.
Of the adaptive filter to minimize the signal level.
Update the filter coefficient. The first simulated transfer characteristic means outputs the output of the compensation signal in the adaptive filter.
In the coefficient updating means via the inverse phase equal sound pressure conversion
Simulating the transfer characteristics of the signal up to the detection of the error signal,
The reference signal that is the input of the adaptive filter is replicated in the model.
Performs initial equalization to correct with pseudo transfer characteristics and updates the coefficient
Means normalize the error signal when updating the filter coefficients
Used to. The second simulated transfer characteristic is the first
1 has a simulated transfer characteristic and the compensation signal is simulated transfer characteristic.
The initial error is corrected by
The reference signal that is the input of the adaptive filter after addition
Used to form the.

The reference sound generating means does not generate the noise.
If the adaptive filter is not used, a noise reference signal is generated.
The reference signal instead of the compensation signal, which is the output of the
And the reference signal instead of the noise reference signal
Is output. The initial equalization determining means is the reference sound generating
Conversion of the reference signal output from the stage instead of the compensation signal
Check signal S obtained by detecting sound, and the adaptive type
The output of the filter is corrected and inverted with the second simulated transfer characteristic
And the check obtained by adding to the check signal S
The error signal N is input, and the check signal and the check signal are input.
The ratio S / N with the error signal N is calculated and based on this S / N
Abnormality of the initial equalization of the first and second simulated transfer characteristics is determined.
Refuse. The coefficient updating unit outputs the check error signal N
To update the filter coefficient of the adaptive filter.
U.

As the reference sound generating means, a sine wave sweep is used when the noise is a sine wave, a harmonic sweep is used when the noise contains harmonics, and an impulse generator is used when the noise is impulsive. Alternatively, storage means for storing noise and outputting the stored noise signal may be used. Further, the initial equalization judging means represents the two input error signals and the reference signal of noise by a cross-correlation function, and compares the time difference between the two signals with a predetermined time to judge deterioration of the initial equalization accuracy. Good.

The noise control device variably controls the output level of the reference sound generating means, and the level of the error signal is detected to cause the variable amplification means to control the amplification degree according to the noise level. Noise level detection means may be provided. The simulated transfer characteristic correcting means simulates the transfer characteristic from the output of the adaptive filter to the input of the coefficient updating means by the noise signal and the signal from the reference sound generating means, and uses the average value of the simulated transfer characteristics. The standardized noise reference signal may be corrected. Initial equalization format
The disconnection means displays the presence or absence of abnormality based on the check of initial equalization
You may do it.

[0011]

According to the noise control device of the present invention, the adaptive filter receives the noise reference signal and automatically changes the filter coefficient to form a compensation signal for eliminating the noise. The residual sound between the noise and the anti-phase equal-sound pressure formed from the compensation signal from the adaptive filter by the coefficient updating means is used as an error signal, and the error signal is normalized by the reference signal of the noise and The filter coefficient is updated. The simulated transfer characteristic correcting means corrects the normalized noise reference signal by simulating the transfer characteristic from the output of the adaptive filter to the input of the coefficient updating means. The reference sound generating means initializes the simulated transfer characteristic set in the simulated transfer characteristic correcting means to generate the white noise used as a reference signal for checking the accuracy of the initial equalization. . When, for example, the white noise signal from the reference sound generating means is selected as the noise reference signal by the initial equalization determining means, the error signal and the noise reference signal are input and the initial equalization is performed from the S / N thereof . The accuracy of is checked and this result is displayed. Therefore, when a problem occurs in the noise control device main body, the speaker, the microphone, etc., the initial equalization accuracy is extremely deteriorated, and this can be easily detected.

As the reference sound generating means, if the noise is a sine wave, a sine wave is swept, and if the noise contains a harmonic wave, a signal containing a harmonic wave such as a triangular wave is swept. In the case of is impulsive, the initial equalization accuracy can be detected more accurately by using an impulse generator and a storage means for storing noise and outputting the stored noise signal.

Further, the initial equalization determining means represents the two input error signals and the noise reference signal by a cross-correlation function, compares the time difference between the two signals with a predetermined time, and deteriorates the initial equalization accuracy. By making the determination, the initial equalization accuracy can be detected more accurately. A noise control device, a variable amplification means for variably controlling the output level of the reference sound generation means, and a noise level detection for detecting the level of the error signal and controlling the amplification degree by the variable amplification means according to the noise level. By providing the means, the accuracy of the initial equalization can be detected even in the presence of noise. The simulated transfer characteristic correcting means simulates the transfer characteristic from the output of the adaptive filter to the input of the coefficient updating means by the noise signal and the signal from the reference sound generating means, and uses the average value of the simulated transfer characteristics. By correcting the normalized noise reference signal, the initial equalization can be detected more accurately even in the presence of noise.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a noise control device according to a first embodiment of the present invention. The noise control device shown in the figure includes a speaker 1 that outputs silence of opposite phase equal sound pressure with respect to noise, a power amplifier 2 that drives the speaker 1, and a power amplifier that removes a high frequency component of an analog signal. 2 and a D / A converter 4 for converting a digital signal into an analog signal and outputting it to the low-pass filter 3.
(Digital to AnalogConverter) and noise to speaker 1
A microphone 5 that is erased by the method and detects a residual sound as an error signal, an amplifier 6 that amplifies a signal from the microphone 5, and a low-pass filter that removes high-frequency components of the amplified signal and prevents the generation of a folding signal. A filter 7 and an A / D converter 8 (Analog to Digital Converte) for converting an analog signal from which the high frequency component has been removed into a digital signal.
r) and FI for outputting the compensation signal to the D / A converter 4.
A filter coefficient of the adaptive filter 9 based on the equation (1) based on the adaptive filter 9 configured by R (Finite Impulse Response), the error signal from the A / D converter 8 and a normalized signal described later. And a normalized signal Te obtained by correcting a reference signal Se , which is a noise signal with a transfer characteristic described later, with a simulated transfer characteristic Hd1.
To the first simulated transfer characteristic correction means 11 for outputting to
Second simulated transfer characteristic correcting means 12 which is the same as the simulated transfer characteristic correcting means 11 of which one is connected to the output side of the adaptive filter 9, and an output signal from the second simulated transfer characteristic correcting means 12 And a signal output from the A / D converter 8 are calculated to obtain a difference reproduction signal, which forms a noise reproduction signal and outputs it to the adaptive filter 9 and the first simulated transfer characteristic correcting means 11. And a white noise generating means 14 for generating white noise used as a reference signal for checking the accuracy of initial equalization, an output of the white noise generating means 14 and an output of the difference signal calculating means 13. The switch means 15 that selectively switches and outputs to the adaptive filter 9 and the first simulated transfer characteristic correcting means 11, and the adaptive filter 9 and the memory noise generating means 14-4 in conjunction with the switch means 15. A switch means 16 to be outputted to the D / A converter 4 switches the power to the alternative, the switch means 1
5 selects the white noise generating means 14 side to enter the initial equalization mode, the error signal from the A / D converter 8 and the noise reproduction signal from the difference signal calculating means 13 are input to S / N
If to derive the initial equalization accuracy the initial equalization <br/> determining means 17 for comparing a predetermined value, the initial equalization accuracy based on the determination in the initial equalization judging means 17 satisfies a predetermined value from Of the A / D converter 8 and the difference signal calculation means 13 in conjunction with the OK lighting means 18 that lights up, the NG lighting means 19 that lights up when the initial equalization accuracy does not satisfy the predetermined value, and the switch means 15. Switch means 22 for selectively switching the output and outputting to the coefficient updating means 10. The coefficient updating means 1
0 is normalized by an error signal from the A / D converter 8 and a signal simulating the transfer characteristic from the first simulated transfer characteristic correcting means 11 based on the above equation (1) to form a filter coefficient, and an adaptive filter Output to 9. Although the above-described noise control system is a feedback system to reproduce the noise signal by combining the compensation signal from the adaptive filter 9 an error signal, white noise is the initial equalization-size <br/> cross section 17 The noise reference signal Swe may be directly output from the means 14.

Here, it is the output of the difference signal calculating means 13.
The noise reproduction signal Se will be described. The noise signal is Sn,
The error signal output from the microphone 5 is changed to Smo and the coefficient is changed.
The input signal Sm to the new means 10 is output from the adaptive filter 9.
The compensation signal Sc, which is the force,
Transfer characteristic Hd from output to microphone 5, microphone
The transfer characteristic from the rophon 5 to the filter coefficient updating means 10.
If the characteristic is Hm, the input signal of the coefficient updating means 10 is Sm = Smo · Hm (2)The other input signal Te becomes the noise reproduction signal Se.
The transfer characteristic Hd1 is calculated by the first transfer characteristic simulating means 11.
Is taken into consideration.The first transfer characteristic simulating means 11,
Transfer characteristic simulated by the second transfer characteristic simulating means 12Hd1
IsHd1 = Hd.Hm (3), the signal Smo detected by the microphone 5 is
Like

Smo = Sn + Sc.Hd (4) Reference of the noise signal which is an input signal of the adaptive filter 9 and the like.
A noise reproduction signal serving as an illumination signal , which is a difference signal calculation means 1
The difference signal Se, which is the calculation result in 3, is obtained from the above equations (2), (3), and (4) by the above configuration as follows. Se = Sm-Sc.Hd1 = Smo.Hm-Sc.Hd1 = (Sn + Sc.Hd) .Hm-Sc.Hd.Hm = (Sn + Sc.Hd-Sc.Hd) .Hm = Sn.Hm ... (5 ) Is formed. The adaptive filter 9 is used to set the input signal Sm of the coefficient updating means 10 to zero so that the equation (1) is satisfied.
Since the filter coefficient is changed by using , the compensation signal Sc which is the output signal of the adaptive filter 7 is determined as follows from the above equation (4) with Sm = 0, that is, Smo = 0.

Sc.apprxeq.-Sn / Hd (6) Next, the formation of the simulated transfer characteristics of the first simulated transfer characteristic correction means 11 and the like will be described. FIG. 2 is a diagram showing a configuration for forming the simulated transfer characteristics of the transfer characteristic simulating means 11 and 12 in FIG. The switch means 20 outputs the white noise from the reference sound generating means 14 to the D / A converter 4, and the switch means 21 prevents the adaptive filter 9 from outputting the white noise to the D / A converter 4. The second simulated transfer characteristic correcting means 12 adjusts the transfer characteristic Hd1 so that the signal from the difference signal calculating means 13 becomes zero.

At this time, with respect to the white noise Sw from the reference sound generating means 14, from equation (5), the input signal of the coefficient updating means 10 due to white noise is Smw: Swe = Smw-Sw.Hd1 (7) = 0 As a result, the simulated transfer characteristic Hd1 is obtained as Hd1 = Smw / Sw (8).

Next, returning to FIG. 1, the judgment of the initial equalization by the initial equalization judging means 17 will be described. As shown in the figure, for example, when the noise control device is started from a stopped state, the input end of the adaptive filter 9 is connected to the white noise generating means 14 side by the switch means 15 without generating noise. At this time, the initial equalization judging means 17 obtains the following S / N as the initial equalization accuracy. Here, the output of the difference signal calculating means 13 is Swe, the noise signal Sn = 0, the error signal which is the output of the microphone 5 is Smwo, and the coefficient updating means 1
The input signal to 0 is Smw, and the compensation signal output from the adaptive filter 9 is Swc.

S / N = | Smw / Swe | ... (9) = | Smw / (Smw-Swc.Hd1) | = | 1 / {(1- (Swc / Smw) .Hd1)} | In FIG. The S / N immediately after setting the simulated transfer characteristics Hd1 of the first simulated transfer characteristic correcting means 11 and the second simulated transfer characteristic correcting means 12 is (S / N) o, and is multiplied by the safety factor a The values are a × (S / N) o and (a <1). (10) The initial equalization judging means 17 compares the above equations (9) and (10), and if S / N ≥ a x (S / N) o, then failure of components constituting the noise control device, etc. If there is no light, the OK lighting means 18 lights up as normal.

If S / N <a × (S / N) o, it is determined that a component of the noise control device has failed, and the NG lighting means 19 turns on the light. As a result, as shown in FIG. 2 again, the second simulated transfer characteristic correcting means 12 is used to obtain the simulated transfer characteristic Hd1 to maintain the noise effect against the deterioration, and it is possible to easily perform the procedure such as exchanging the constituent articles. become.

Instead of the reference signal of the noise from the reference sound generating means 14, if the noise source is close to a sine wave, a sine wave is swept and used, and if the noise source includes a harmonic wave, a harmonic wave such as a triangular wave is included. If the noise source is an impulsive sound source, the signal may be swept to perform initial equalization using an impulse generator. It is also possible to store the noise from the noise source in a storage means (not shown) and use this as a noise reference signal for initial equalization. Such a method is also used for checking the accuracy of initial equalization described later.

In the above description, the white noise generating means 14 is used when checking the initial equalization accuracy, but instead of this, the sine generating means 14-1 which generates a sine wave may be used. Thereby, when the noise wave is close to a sine wave, the physical characteristics of the microphone 5 and the like can be more accurately equalized. Next, instead of the sine wave generating means 14-1, a harmonic generating means 14-2 using a harmonic generator such as a triangular wave may be used. When the noise wave includes harmonics, the physical characteristics of the microphone 5 and the like can be more accurately equalized.

Further, instead of the harmonic generating means 14-2, the impulse generating means 14-3 using an impulse sound source may be used. When the noise wave is close to an impulse, the physical characteristics of the microphone 5 and the like can be more accurately equalized. Further, instead of the impulse generating means 14-3, a memory noise generating means 14-4 that stores noise and generates the stored noise as a reference signal may be used. The memory noise generating means 14-4 is composed of a RAM (Random Access Memory). When noise is stored, the noise output from the speaker 1 is stopped, and the A / D converter 8 is supplied via the microphone 5.
From the memory noise generating means 14-4. Output from the memory noise generation means 14-4 via the switch means 15 as described above. As a result, more accurate equalization can be performed by equalizing the sound closer to the noise source.

Next, another configuration of the initial equalization judging means 17 will be described. The initial equalization determining means 17 calculates the S / N from the equation (9).
Difference signal calculation means 13 input by the conversion determination means 17-1
Of the output signal Swe and the output signal Smw of the A / D converter 8 are measured to determine the accuracy of the initial equalization. The initial equalization determination means 17-1 uses the following equation to calculate two signals x
The cross-correlation function Rxy (τ) of (t) and y (t) is represented.

[0026]

[Equation 1]

Here, T is the observation time, τ is the time difference of random time history memory, and τ at which a peak occurs in this cross-correlation function is the delay time of the system. For this reason, the two signals Swe and Smw are made to correspond to the above two signals x (t) and y (t), and a reference delay time τo is provided in advance with respect to the delay time τ and becomes larger than this time. Then, it is determined that the deterioration of the initial equalization accuracy has occurred.

FIG. 3 is a flow chart for explaining a series of operations of the first embodiment. As shown in this figure, in step 1, initial equalization is first performed when the noise control device is started. For this purpose, as shown in FIG.
And 21 to switch to the initial equalization mode. In this way, the first and second simulated transfer characteristic correcting means 11 and 12
Set simulated transfer characteristics to.

In step 2, the switch means 15, 16 and 22 in FIG. 1 are switched to the equalization accuracy judgment mode. In the initial equalization judging means 17 etc., the initial equalization precision is obtained from the output signal Smw of the A / D converter 8 and the output signal Swe of the difference signal calculating means 13 by the above-mentioned method. It is determined whether or not this initial equalization accuracy is larger than a predetermined threshold value.
In step 3, if the initial equalization accuracy is less than or equal to the threshold value,
Since the parts constituting the noise control device are normal, the OK lamp is turned on by the OK lighting means 18.

In step 4, the data obtained by the initial equalization is stored in a storage means (not shown) so that it can be used for tracking changes over time. In step 5, the switch means 15, 16 and 22 shown in the figure are put into a normal operation mode to perform noise control. In step 6, if the equalization precision is equal to or higher than the predetermined threshold value in step 2, the NG lighting means 19 gives a failure display. This makes the second
The simulated transfer characteristic correction means 12 determines the simulated transfer characteristic or replaces the failed component.

The above-mentioned initial equalization and its accuracy judgment need to be performed even in the presence of noise, but if a noise signal other than the reference signal is included from the reference sound generating means 14, sufficient initial equalization cannot be performed. , Its accuracy cannot be determined. The case where there is noise will be described below. FIG. 4 is a partial view showing a noise control device according to the second embodiment of the present invention. The noise control device shown in this figure includes a reference sound generating means 14 and a switching means 1.
The variable amplification means 30 for variably amplifying the output signal of the reference sound generation means 14 between 5, 16, and 20 and the level of the output signal of the A / D converter 8 are detected to control the amplification degree of the variable amplification means 30. The noise level detection means 31 is included. According to the present embodiment, the level detecting means 31 detects the noise level amplitude level before the equalized signal is generated, outputs the equalized signal at a level higher than the level, and outputs the signal greater than the noise. The accuracy of the equalization and the accuracy of the equalization determination are improved.

The above is effective when the noise level is large to some extent, but if the noise level is too large, the amplification degree of the variable amplifying means 30 is limited to a certain extent. Therefore, the initial equalization that can be set in such a case will be described below.
Figure 5 is a flowchart illustrating the initial equalization under noisy according to a third embodiment of the present invention. As shown in the figure, in step 10, the ordinal number j = 1 is set.

In step 11, the simulated transfer characteristic Hd1 (j) is measured so that the output signal Swe of the difference signal calculating means 13 in FIG. 2 is minimized. The features of this embodiment will be described below. By utilizing the fact that there is no correlation between the white signal from the harmonic generating means 14 and noise, the simulated transfer characteristics for each measurement are affected by noise and are not constant, but there are multiple It is assumed that, if the measurements of two times are averaged, there is no correlation with noise, and therefore only the transfer characteristics of the reference signal due to white noise can be obtained.

In step 12, Hd1 (j) is stored in the storage unit (not shown). In step 13, the number of measurements j
Determines whether the number has reached a predetermined number n. Step 1
In step 4, if the number of measurements has not reached the predetermined number in step 13, the ordinal number is increased and the process returns to step 11. In step 15, when the number of measurements reaches a predetermined value in step 13, the simulated transfer characteristic Hd1 (j) stored in step 12 (j =
1-n) are read and averaged as follows.

Hd1 = {Hd1 (1) + Hd1 (2) + ... + H
d1 (n)} / n In step 16, the simulated transfer characteristics obtained in step 15 are set in the first and second simulated transfer characteristic correcting means 11 and 12.

[0036]

As described above, according to the present invention, when the white noise signal from the white noise generating means is selected as the noise reference signal by the initial equalization judging means, the error signal and the noise Since the accuracy of the initial equalization is checked from the S / N based on the reference signal and the result is displayed, the accuracy of the initial equalization is extremely deteriorated when a problem occurs in the noise control device body, the speaker, the microphone, or the like. So this can be detected easily.

[Brief description of drawings]

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

FIG. 2 is a transfer characteristic simulating means 11 and 12 in FIG.
5 is a diagram showing a configuration for forming a simulated transfer characteristic of FIG.

FIG. 3 is a flowchart illustrating a series of operations of the first embodiment.

FIG. 4 is a partial view showing a noise control device according to a second embodiment of the present invention.

5 is a flowchart illustrating an initial equalization <br/> under noise according to a third embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Speaker 5 ... Microphone 9 ... Adaptive filter 10 ... Coefficient update means 11 ... 1st simulated transfer characteristic correction means 12 ... 2nd simulated transfer characteristic correction means 13 ... Difference signal calculation means 14 ... Reference sound generation means 15, 16, 20, 21 ... Switch means 17 ... Initial equalization determination means 18 ... OK lighting means 19 ... NG lighting means 30 ... Variable amplification means 31 ... Noise level detection means

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masahiro Babasaki 1-2-2 Goshodori, Hyogo-ku, Kobe-shi, Hyogo Within Fujitsu Ten Limited

Claims (11)

(57) [Claims] 1. A noise control device for forming a compensating signal for anti-phase equal-sound pressure with noise, wherein a noise reference signal is input to automatically change a filter coefficient.
An adaptive filter (9) for outputting the compensation signal, and a residual sound resulting from the interference of the anti-phase equal sound pressure and the noise as an error signal.
To minimize the level of this error signal
Responsible for updating the filter coefficient of the adaptive filter (9)
Number updating means (10) and output of the compensation signal in the adaptive filter (9)
To the coefficient updating means (1
0) Signal transfer characteristics up to detection of the error signal in 0)
Which is the input of the adaptive filter (10).
Initial equalization for correcting the reference signal with the simulated transfer characteristic
Then, the coefficient updating means (10) updates the filter coefficient.
The first used to normalize the error signal when new
And a simulated transmission characteristic means (11) for simulating the compensation signal.
The above-mentioned error
It is the input of the adaptive filter (9) which is added to the signal.
A second simulated transmission used to form the reference signal
Achievement characteristics (12) and generate a noise reference signal when the noise does not occur
The compensation signal output from the adaptive filter (9).
Output the reference signal instead of the signal and refer to the noise
Reference sound generating means for outputting the reference signal instead of the signal
(14) , instead of the compensation signal from the reference sound generating means (14)
The converted sound of the reference signal output to the
Check signal S and the output of the adaptive filter (9)
It is corrected by the second simulated transfer characteristic and inverted to check the check signal.
Input the check error signal N obtained by adding to the signal S
And the ratio of the check signal and the check error signal N
S / N is taken, and based on this S / N, the first and second
Judge abnormalities in initial equalization of simulated transfer characteristics (11, 12)
And an initial equalization judging means (17) for updating the coefficient.
The unit (10) uses the check error signal N to
A noise control device characterized by updating a filter coefficient of an adaptive filter (9) . 2. The noise control device according to claim 1, wherein said reference signal generating means (14) also generates white noise as a reference signal. 3. The noise control device according to claim 1, wherein when the noise is similar to a sine wave, a sine wave is used as a reference signal by sweeping within a control band frequency as the reference sound generating means (14). . 4. The reference signal generating means (14),
The noise control device according to claim 1, wherein when the noise includes harmonics, a signal including harmonics such as a triangular wave and a rectangular wave is used as a reference signal by sweeping within a control band. 5. The noise control device according to claim 1, wherein when the noise is impulsive, an impulse reference sound is used as the reference sound generating means (14). 6. The noise control device according to claim 1, wherein a memory means for storing noise and outputting the stored noise signal is used as the reference sound generating means (14). 7. The initial equalization judging means (17) represents the two input error signals and noise reference signal by a cross-correlation function, and compares the time difference between the two signals with a predetermined time to perform initial equalization. The noise control device according to claim 1, wherein accuracy is determined. 8. The reference sound generating means (14) outputs the sound.
Variable amplification means (30) for variably controlling the force level, and
The level of the error signal is detected and the above
A noise level for controlling the amplification degree by the variable amplification means (30).
A device (31) for detecting a fault.
1. The noise control device according to 1. 9. The noise control device according to claim 8, wherein said reference signal generating means (14) generates white noise as a reference signal. 10. The simulated transfer characteristic correction means (11)
Is a mean value of the simulated transfer characteristics obtained by simulating the transfer characteristics from the output of the adaptive filter (9) to the input of the coefficient updating means (10) by the noise signal and the signal from the reference sound generating means (14). using, noise control apparatus according to claim 1 or 8, wherein correcting the reference signal of the normalized noise. 11. The noise control device according to claim 1, wherein the initial equalization judging means (17) displays the presence or absence of an abnormality based on a check of the initial equalization.