JPH0659688A - Method and device for active noise elimination and related active noise eliminating device for running vehicle - Google Patents

Abstract

PURPOSE:To positively eliminate road noise which arises from a suspension and body vibration when a vehicle runs. CONSTITUTION:Vibration during running is detected by acceleration sensors 1-4 and the detection signals are added in an addition circuit 20 to make up a reference signal 105. The 105 is inputted to a microprocessor 13 via an A/D convertor 12 for applicable signal processing, and then it is outputted as an output control signal 107 and issued in the form of secondary sound from speakers 9-10 via a D/A convertor 14 and a power amplifier 15 to eliminate road noise at the position of microphones 5-8. As the high-coherence reference signal can be supplied in less numbers by adding the plural detection signals, a noise eliminating device can be constructed into a small system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a closed space (for example, a passenger compartment) generated by a plurality of vibrations propagating from a plurality of vibration sources such as tires and suspensions when a vehicle is running.
The present invention relates to an active noise reduction method and device that actively mute internal noise (random noise).

It is particularly suitable for silencing the vehicle running noise (road noise).

[0003]

2. Description of the Related Art A technique for silencing random noise will be described in detail below based on an example of vehicle running noise.

The noise generated during the operation of the vehicle includes engine noise, wind noise, road noise, and the like. Among them, the vibrations of the tire and the suspension due to the unevenness of the road surface during traveling are propagated into the vehicle interior. The generated noise is generally called road noise and usually has a broadband spectrum of 30 to 300 Hz. Road noise is generated even on a rough road surface at a speed of about 40 to 60 km / h, and it is an unpleasant sound for humans. Therefore, various efforts have been made to reduce it.

Incidentally, as a countermeasure against these noises, a so-called "passive" method such as a change in the structural design of the vehicle body or a countermeasure using a sound insulating material is generally used. On the other hand, active noise control technology has been attracting attention that artificially creates a secondary sound having an opposite phase to the generated noise to "actively" eliminate the sound. In particular, as an example of research on a system that uses a secondary sound source to actively mute road noise, see, for example, the document “Active Noise and V
ibration Control witin the Automobile ”, AM Mcdona
ld, et al, International Symposium on Active Contro
l of Soundand Vibration, ASJ Proc. '91. Tokyo, Apr
il 9-11, 1991, pp. 147-156. Among them, AM Mcdonald and colleagues used the vibration of the rear suspension as a reference signal using the measurement output of two accelerometers mounted close to the wheel hub as an active component consisting of two microphones and two speakers. We have reported an example where the noise reduction system can significantly reduce the noise level near 100 Hz at the position of the rear seat.

This basic idea of active noise control is old, and since the pioneering research conducted by Lueg in the 1930s, research has been conducted by Olson, Conver, etc. in the 1950s. It has been relatively recently applied to products. This is largely due to the advent of high-speed arithmetic elements for enabling control such as digital signal processors, but it can also be mentioned that the theoretical aspects of control algorithms have been improved.

Examples of recent noteworthy research on active noise control technology are GBBChaplin (for example, Japanese Patent Publication No. 56-501062) and PANelson / SJElliot (for example, Japanese Patent Publication No. 501501344). I can give an example. The difference between the two control methods is that the former control uses "repetitive control" that assumes the periodicity of the target noise, while the latter control uses the LMS (Least Mean) method, which is a type of steepest descent method. Square: Least squares method)
Since the adaptive signal processing using the algorithm is performed, the target noise does not necessarily need to be periodic.

This LMS adaptive control algorithm is 195
Although it is a method systematized by Widrow in the 0's, most of recent studies on active noise control rely on this control algorithm because of its versatility. In the present invention as well, since the use of this control algorithm is basically premised, the above-mentioned Published Patent Publication No. 1-501344 (PANe
lson / SJElliot) is taken as an example to explain the conventional technology.

FIG. 7 shows an active noise control apparatus described in the above-mentioned publication, which silences a specific closed space such as a vehicle interior by a plurality of loudspeakers and microphones. This is to output a secondary sound for reducing noise by interfering with primary sound (noise) and secondary sound at three microphone positions for measuring sound pressure at a predetermined position in a closed space and each microphone position. Two loudspeakers,
Reference signal generator for generating a signal in synchronization with engine rotation, control circuit having a first-order adaptive filter for driving a loudspeaker by outputting a signal for driving a speaker by phase-amplitude modulating the reference signal It is composed of.
In addition, an engine rotation signal (for example,
An ignition timing signal, a crank angle sensor signal, etc.) are input, and the reference signal generator generates a sine wave signal proportional to an integral multiple of the momentary engine rotation period.

In the LMS adaptive control algorithm, the coefficient of the adaptive filter is updated every moment so that the square value of the sound pressure at each microphone position is minimized. However, the primary sound and the secondary sound interfere well with each other. To reduce noise,
A component having a sufficiently high correlation with the primary sound in the standard signal or the reference signal which is the source of the standard signal must be included. Usually, a dimensionless quantity that takes a value between 0 and 1 is called coherence (coherence) as an index showing the degree of correlation between two signals. From the result of rigorous theoretical analysis, it is known that the noise reduction amount by the active noise control system based on the LMS adaptive control algorithm is determined by the value of this coherence.

In the active noise control device in the passenger compartment of an automobile as shown in FIG. 7, the noise caused by the rotational vibration of the engine is the control target, and the engine rotation signal is supplied as a reference signal and synchronized with this. By generating a sine wave signal, a reference signal with high coherence (coherence) with respect to engine noise components is obtained. For example, when the engine is a four-cycle four-cylinder engine, vibration with a frequency twice the engine rotation is large, and is generally called engine secondary vibration. This is due to gas torque fluctuations due to gas combustion every 1/2 rotation and inertia torque fluctuations due to imbalance of the crankshaft system moment. Then, this becomes an exciting torque to vibrate the vehicle body, and this is propagated into the vehicle interior to generate standing wave noise. Therefore, at this time, the active noise control of the secondary vibration noise becomes possible by supplying the rotation signal for each crank angle of 180 degrees as the reference signal.

[0012]

By the way, since the engine muffled sound as described above is basically a periodic sound synchronized with the engine rotation and has a single frequency, it can be said that it is relatively easy to control. On the other hand, road noise is basically random noise because it is caused by random vibration due to unevenness of the road surface during traveling, and has a broad band spectral structure as shown in an example in FIG. There is.
Further, the vibrations from the road surface to the tires are random in the directions of up, down, left and right, front and back, and are input from four wheels. That is, the road noise is composed of a plurality of noise sources. These pose various technical constraints in constructing a system that actively silences road noise.

First, the reference signal required for control needs to include road noise and a component having a sufficiently high coherence. As the reference signal sensor, it is possible to attach an acceleration sensor to a portion of the suspension. However, as described above, there are a plurality of vibration sources of road noise, and the contribution rate per sensor is small with respect to the whole. In general, an amount called multicoherence, which is an extension of the concept of coherence, is defined as an index showing the degree of correlation between a plurality of input signals and an output signal. In order to detect all the vibrations transmitted to the vehicle body in order to obtain sufficient multicoherence in the entire reference signal against road noise, ideally 3 axes per wheel, 4 axes
It is necessary to detect the vibration of a total of 12 axes by the wheel, and 12 acceleration sensors are required.

Furthermore, the number of acceleration sensors and noise detection microphones also defines the system size of the control unit. In general, an adaptive filter models the vibro-acoustic transfer function between each noise source (excitation source) and each microphone, so the number of filters is theoretically the number of sensors multiplied by the number of microphones. It is necessary (for example, 12 acceleration sensors and 4 microphones, 12 × 4 = 48). Further, since the road noise has a wide band spectrum, the tap length of the adaptive filter must be long enough to express it.

Further, unlike periodic sounds such as muffled sounds, road noise is random noise and therefore has no reproducibility. Therefore, before the random vibration is transmitted from the suspension to the vehicle body to generate noise inside the vehicle and the passenger's ears detect it, the speaker also has the capability of high-speed arithmetic processing to generate a secondary sound of opposite phase and mute it. Required for active silencers.

All of these cause an increase in system scale, making it difficult to realize an active silencer.
Therefore, it is an object of the present invention to improve multicoherence with the smallest possible number of sensor reference signals in order to make the system a feasible size.

[0017]

In order to achieve the above object, in the present invention, at least one of a plurality of vibrations propagating to a sound dead space and / or a composite vibration of a plurality of vibrations is applied to a surrounding environment. The vibration is selected according to the selected vibration, and the vibration or sound for silencing is generated based on the selected vibration.

Specifically, one or a plurality of noise detecting means and one or a plurality of secondary sound outputting means for actively canceling the noise are used to detect a vibration of the suspension or the vehicle body. And an adaptive signal processing means for adaptively generating a secondary sound control signal from the reference signal so as to minimize a certain evaluation function by using the detection signal obtained from the vibration detection means as a reference signal. An active noise canceling device for vehicle running noise, comprising: adding means for adding the plurality of detection signals, combining the detection signals in an arbitrary combination according to the running conditions, adding the number of detection signals, and applying the reference signal as the reference signal. The configuration is such that it can be supplied to the signal processing means. According to the improved technology, a low-pass filter that passes only a band below a preset frequency for each detection signal, a high-pass filter that passes only a band above a preset frequency, and a band that passes only a preset specific frequency band A pass filter is prepared, and the detection signals after passing through the filters can be arbitrarily combined according to the running conditions, added in the number of them, and added to the adaptive signal processing means as a reference signal. further,
The addition after passing through the filter is divided into preset specific frequency bands and added as reference signals, and the number of taps and sampling frequency of the adaptive digital filter for each reference signal are set separately. . Furthermore, the periodic single frequency component included in the detection signal is emphasized and detected by a bandpass filter having a steep characteristic, and the signal after passing through the filter is used as a reference signal for the periodic single frequency component. The adaptive signal processing means for selectively performing adaptive signal processing on only one is configured independently of the adaptive signal processing means for other components.

[0019]

According to the present invention thus constructed, the number of reference signals can be reduced, so that the number of adaptive filters can be reduced and the system can be realized.

In an active noise reduction system for vehicle running noise to which this is applied, many sensors are required to detect vibrations of tires and suspensions, but the reference signal is only the reference signal required according to the running state. Since it can be selected and used, the number of adaptive filters can be configured with a practical number, and the system feasibility can be improved.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The contents of the present invention will be described below in detail with reference to the method and apparatus for actively canceling vehicle running noise shown in the drawings.
FIG. 1 shows the overall configuration of an active noise reduction device for road noise. In the figure, the active silencer is an acceleration sensor 1-4 (here,
The acceleration sensor may be of a type capable of detecting accelerations in a plurality of directions), a noise detection microphone 5-8 arranged in the vehicle compartment, and a speaker 9-for outputting a control sound (secondary sound) for silencing. 10, a controller 11 for silencing control, and the like.

When the tire is vibrated by the unevenness of the road surface and each suspension vibrates during traveling, the acceleration sensor 1
-4 detects the vibration acceleration, and the detection signal 101-10
4 is supplied to the controller 11. In the controller 11, the detection signals are added by the addition circuit 20 in an appropriate combination to create a reference signal (in the figure, the case where two reference signals are created is shown). Then, the reference signal 10
5 is sent to the A / D converter 12 and the digital signal 106
Is converted to. The microprocessor 13 in the controller 11 performs a convolution operation on the input digital signal 106 using an adaptive digital filter (abbreviated as ADF) to generate a speaker output control signal 107. The output control signal 107 is amplified by the power amplifier 15 via the D / A converter 14 and is output as a secondary sound by the speaker 9-10. On the other hand, the ADF detects the sound pressure inside the vehicle by the microphone 5-8 and outputs the detection signal to the A / D.
Input to the microprocessor 13 via the converter 16. Then, the adaptive control algorithm programmed in the microprocessor 13 constantly adjusts the ADF output so that the sum of the squared values of the sound pressure in the vehicle interior is minimized, whereby the secondary sound output of the speaker 9-10 is output. Has always been optimized.

Here, the adjustment of the ADF filter coefficient is performed by Mu.
ltiple Error Filtered-x LMS algorithm (MEF
X-LMS algorithm). (For details of the MEFX-LMS algorithm, refer to, for example, the document “Signal Processing for Active Cont.
rol−Adaptive Signal Processing− ”, Hareo HAMAD
A, International Symposium on Active Control of So
und and Vibration, ASJ Proc. '91, Tokyo, April 9
-11, 1991, pp. 33-44, etc. are described in detail here, and are omitted here. Here, FIG. 2 shows a first embodiment of the present invention, and relates to a method of adding detection signals by the analog adder circuit 20, creating a reference signal, and a method of switching the input to the ADF. However, in the case of the same figure, the eight sensor detection signals 111-118 to the eight reference signals 1 are processed by the addition circuit 20 including the eight acceleration sensors 31-38 and the eight analog adders 21-28.
21-128 is created. (Here, the detection signal addition method shown in the figure is merely an example, and other combinations may be used.) First, the output signals 121-128 of the analog adders 201-208 are:
The digital signal 13 by the 8-channel AD converter 21
It is converted to 1-138 and sent to the microprocessor 13. Here, first, only the digital signals 131-134 corresponding to the analog signals 121-124 are used as reference signals, and the ADF and convolution operation are performed. on the other hand,
When the vehicle speed exceeds a certain set speed, the reference signal is switched. That is, the digital signals 135-138 corresponding to the analog signals 125-128 are used as reference signals and are used in the convolution operation with the ADF.

FIG. 3 shows the mute control block based on the reference signal generated in FIG. 2 in more detail. In the figure, there are two speakers and two microphones,
8 ADFs, 2 for each of the 4 reference signals
A convolution operation is performed with the filter coefficients of 41-48. The calculation result 141-148 is the adder 51-5.
Speaker output control signal 151 by adding four by 2
It becomes -152. These are the D / A converters 5, respectively.
3 and 54, low-pass filters 55 and 56, and power amplifiers 57 and 58 to output from the speaker 9-10. And each filter coefficient of ADF is microphone 6
Using the detection signals of 1,62, the sum of squares of these is corrected from time to time.

Next, FIG. 4 shows a second embodiment of the present invention. This figure shows detection signals 161-from six sensors.
This is a case where high-pass filters 71-76, band-pass filters 81-86, and low-pass filters 91-96 are prepared for 166, respectively. The signals after passing through the respective filters are added six by six as shown in the figure to form three reference signals 171-173. Each reference signal is high pass,
Bandpass. Two low-pass filter-passed signals are added, each of which is designed to minimize the decrease in multicoherence by basically selecting signals with low correlation in the filter-pass frequency band. ing.

Next, FIG. 5 shows a third embodiment of the present invention in which the number of taps and the sampling frequency of the adaptive digital filter to be convoluted with each reference signal after the detection signal addition are set separately. Is. In the figure,
Each of the three sensor detection signals 181 to 183 is passed through a high pass filter, a band pass filter, and a low pass filter, and the signals passed through the same filter are added. As a result, each reference signal is decomposed into high, medium, and low frequency bands. Generally, it is said that the sampling frequency of the digital filter (and A / D conversion) for the analog signal should be at least twice as high as the highest frequency component included in the detection signal, so that sampling for lower frequency components is performed. The frequency can also be set low.
Therefore, in FIG. 5, the adaptive filters ADF ₁ , ADF ₂ , and
Different sampling frequencies f ₁ , f ₂ and f ₃ (f ₁ > f ₂ > f ₃ ) are set for the ADF ₃ .

Here, the adaptive digital filter AD
The convolution operation in F ₁ , ADF ₂ and ADF ₃ can be expressed by the following equation.

[0028]

[Equation 1]

X _{1 to} X ₃ : adaptive filters ADF _{1 to} ADF ₃
Reference signal to the input Y ₁ to Y _3: adaptive filter ADF ₁ control from ～ADF ₃ signal output W ₁ to _W-3: adaptive filter ADF ₁ ~ADF ₃ of filter coefficients n ₁ ~n _3: sampling frequency f ₁ ~ Sample sequence for f ₃ I _{1 to} I ₃ : Number of filter taps of ADF _{1 to} ADF _{3 In} the number 1 and FIG. 5, adaptive filters ADF ₁ , ADF ₂ ,
The number of taps of ADF ₃ is also set to a value different from I ₁ , I ₂ , and I ₃ , respectively. Generally, the acoustic vibration transfer characteristics of a vehicle have frequency dependence, and the vibration damping characteristics differ between low frequency vibration and high frequency vibration. In the case of the same sampling frequency, the number of taps needs to be increased as the vibration damping is slower. In this way, the adaptive signal processing is performed on the reference signal by decomposing it for each frequency band at the optimum sampling frequency and the optimum number of taps.

Next, FIG. 6 shows a fourth embodiment of the present invention, in which only a single frequency component having periodicity is selectively applied in parallel with the original adaptive signal processing system for broadband spectrum noise. An example in the case of having a system for signal processing is shown. As can be seen by observing the road noise spectrum of FIG. 7 in detail, generally, road noise is a broadband spectrum having a random property, but the resonance point of the vibration transmission system of the vehicle body, the air column resonance of the tire, etc. Therefore, a strong line spectrum often exists at a specific frequency. In Fig. 7, a strong line spectrum due to the cavity resonance of the tire is observed near 250 Hz, but such a spectrum is a single frequency component having a strong periodicity and is controlled together as a part of broadband random noise. Rather, aiming only at that component is superior in control efficiency. Therefore, in FIG. 6, for the adaptive signal processing system 30 for the original random noise,
The adaptive signal processing system 40 for periodic single frequency noise is independently configured, and the respective output signals are added by the adding circuit 50, supplied to the amplifier, and output from the speaker. Here, the input signal 401 to the adaptive signal processing system 40 is one of the detection signals input to the adaptive signal processing system 30.
The input signal is input to the ADF 80 via the bandpass filter 60 having a steep characteristic that passes only the vicinity of the specific frequency of interest and the A / D converter 70. A
Since the DF80 only needs to express a single frequency, the number of filter taps may be small. (In principle, it can be expressed with two taps.) Then, the output of the ADF 80 is sent to the analog adder 50 via the D / A converter 90 and becomes a part of the speaker control signal.

The present invention can be applied to all objects in which vibrations propagating to the sound deadening space are randomly generated from a plurality of excitation sources. For example, vibration due to waves of a ship, vibration due to exchange with the wind of an aircraft, vibration from multiple vibration sources (air conditioners, refrigerators, water, pumps) such as buildings and houses causes random noise corresponding to road noise in the case of vehicles. It becomes a generation source. It is more effective when combined with a conventional active noise canceling device for noise based on secondary rotational vibration.

[0032]

According to the present invention, since the number of reference signals input to the system can be reduced by the method of adding detection signals, the system scale can be further reduced and the product can be supplied at a lower cost. .

[Brief description of drawings]

FIG. 1 shows the configuration of an active noise reduction device for road noise.

FIG. 2 is a method of adding detection signals and creating a reference signal.

FIG. 3 is a silencing control block based on a reference signal input.

FIG. 4 is a second example relating to reference signal generation.

FIG. 5 is an embodiment relating to reference signal generation and adaptive filter calculation.

FIG. 6 shows an embodiment in which control systems for single frequency noise are operated in parallel.

FIG. 7 is an explanatory diagram of a conventional active noise control device.

FIG. 8 is an example of a spectral distribution of road noise.

[Explanation of symbols]

1-4 ... Acceleration sensor, 5-8 ... Microphone, 9-
10 ... Speaker, 11 ... Controller, 12, 16 ... A
/ D converter, 13 ... Microprocessor, 14 ... D / A
Converter, 15 ... Amplifier, 101-104 ... Sensor detection signal, 105 ... Reference signal, 107 ... Output control signal.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuhide Sasaki 2520 Takaba, Takata, Ibaraki Prefecture, Hitachi Automotive Equipment Division (72) Inventor Koji Abe 2520, Takaba, Katsuta, Ibaraki Hitachi, Ltd. Mfg. Co., Ltd. Automotive Equipment Division (72) Inventor Yasuo Azuma 2477 Kashima Yatsu Kashima, Katsuta City, Ibaraki Pref. 3 Hitachi Automotive Engineering Co., Ltd.

Claims (13)

[Claims] 1. A device for silencing a standing wave sound by causing a standing wave sound generated by a plurality of vibrations propagating in a sound dead space to interfere with a sound supplied into the sound dead space, wherein one of the plurality of vibrations One and / or one of the combined vibration signals obtained by combining any one of the vibrations is selectively output according to the surrounding environment of the sound dead space, and the supplied sound is output based on the selected vibration signal. An active muffling method characterized by: 2. At least one sound generating device arranged in the sound deadening space, at least one sound detecting sensor arranged in the sound deadening space, and each excitation source of a plurality of vibrations propagating in the sound deadening space. Vibration sensors provided respectively, vibration signal generation means for generating a vibration signal having a phase opposite to that of the sound detected by the sound detection sensor based on the output signals of the plurality of vibration sensors, and the sound based on this vibration signal. An active silencer comprising a driving unit for driving a generator, wherein the vibration signal generating unit synthesizes one of the output signals of the plurality of vibration sensors and / or a plurality of output signals of the vibration sensors. Has a function of selectively outputting one of the combined signals according to the operating state of the engine, and based on the selected vibration signal, a vibration having a phase opposite to the noise detected by the noise detection sensor. Generating a No., active silencer, characterized in that. 3. At least one sound generating device arranged in the vehicle compartment, at least one sound detecting sensor arranged in the vehicle compartment, vibration sensors respectively provided in a plurality of vibration sources, and outputs of the plurality of vibration sensors. A vehicle traveling comprising: a vibration signal generating means for generating a vibration signal having a phase opposite to that of the sound detected by the sound detecting sensor based on the signal; and a driving means for driving the sound generating device based on the vibration signal. An active noise canceling device for noise, wherein the vibration signal generating means outputs one of a plurality of output signals of the plurality of vibration sensors and / or a combined signal of a plurality of output signals of the vibration sensors. It has a function of selectively outputting depending on the operating state of the engine, and based on the selected vibration signal, generates a vibration signal having a phase opposite to the noise detected by the noise detection sensor. Active silencer device for a vehicle traveling noise. 4. At least one speaker arranged in the vehicle compartment, at least one microphone arranged in the vehicle compartment, acceleration sensors respectively provided in a plurality of vibration sources, and based on output signals of the plurality of acceleration sensors. An adaptive filter for generating a vibration signal having a phase opposite to that of the sound detected by the microphone, and a driving means for driving the speaker based on the vibration signal, Further, a vibration signal selecting means for selectively outputting one of the output signals of the plurality of vibration sensors and / or one of the combined signals of the plurality of output signals of the vibration sensor depending on the operating state of the engine. , Based on the vibration signal selected by the vibration signal selection means, the adaptive filter has a phase opposite to that of the noise detected by the noise detection sensor. Generating an oscillating signal, the active silencer of the vehicle running noise, characterized in that. 5. At least one noise detecting means, at least one secondary sound outputting means for actively canceling the noise, and a plurality of vibration detecting means for detecting the vibration of the suspension or the vehicle body. Using the detection signal obtained from the vibration detection means as a reference signal, adaptive signal processing means for adaptively generating a secondary sound control signal from the reference signal so as to minimize a certain evaluation function, An active silencer, which has addition means for adding the plurality of detection signals, and is capable of arbitrarily setting the combination and the number of signals to be added depending on the running condition. An active noise reduction system for vehicle running noise, wherein the added signal is supplied as a reference signal to the adaptive signal processing means. 6. The active silencer is a low-pass filter that passes only a band below a preset frequency for each of the plurality of detection signals, a high-pass filter that passes only a band above a set frequency, and a preset. Each bandpass filter that passes only a specific frequency band is prepared, and the detection signal after passing through the filter can be added in any combination and in any number according to the running conditions by the addition means, and the obtained addition signal is referred to. The active noise canceling system for vehicle running noise according to claim 5, characterized in that it can be supplied as a signal to the adaptive signal processing means. 7. The active muffling apparatus divides and adds for each preset specific frequency band by the low pass filter, the high pass filter, and the band pass filter,
7. The active noise canceling system for vehicle running noise according to claim 5, wherein the respective added signals are used as reference signals, and the number of taps and the sampling frequency of the adaptive digital filter for each reference signal are set separately. . 8. The active silencer has a bandpass filter having a steep characteristic for emphasizing and detecting only a periodic single frequency component contained in a detection signal, and a signal after passing through the filter. 6. An adaptive signal processing means for selectively performing adaptive signal processing only on the periodic single frequency component as a reference signal is provided independently of the adaptive signal processing means for other components. An active noise reduction system for vehicle running noise according to any one of claims 1 to 7. 9. The adaptive signal processing means is configured to include an adaptive filter, and the coefficient of the adaptive filter is updated every moment so that the square value of the sound pressure at the microphone position is minimized. The active noise reduction system for vehicle running noise according to claim 5, 10. A method in which a standing wave sound generated by a plurality of vibrations propagating in a sound dead space is interfered with a sound supplied into the sound dead space to mute the standing wave sound, wherein the plurality of vibrations are synthesized. An active muffling method characterized in that a sound to be supplied into the muffling space is generated based on the synthesized vibration signal. 11. At least one sound generator disposed in the noise-reduced space, at least one sound detection sensor disposed in the noise-reduced space, and excitation sources for a plurality of vibrations propagating in the noise-reduced space. Vibration sensors provided respectively, vibration signal generation means for generating a vibration signal having a phase opposite to that of the sound detected by the sound detection sensor based on the output signals of the plurality of vibration sensors, and the sound based on this vibration signal. An active noise suppressor comprising: a driving unit that drives a generator, wherein the vibration signal generating unit detects the noise detection sensor based on a combined signal obtained by combining the output signals of the plurality of vibration sensors. Generates a vibration signal in the opposite phase to noise,
An active silencer characterized by the above. 12. A method for canceling the standing wave vibration by causing a standing vibration wave generated by a plurality of vibrations propagating to the sound deadening space to interfere with a vibration wave artificially supplied into the sound deadening space, Based on the selected vibration signal, one of the plurality of vibrations and / or one of the combined vibration signals obtained by combining any of the vibrations is selectively output depending on the surrounding environment of the silenced space. And an artificially-supplied vibration wave is generated. 13. At least one vibration generator disposed in the noise-reduced space, at least one standing-wave vibration detection sensor disposed in the noise-reduced space, and each of a plurality of vibrations propagating in the noise-reduced space. A vibration sensor provided on each of the vibration sources, a vibration signal generation means for generating a vibration signal having a phase opposite to that of the vibration detected by the standing wave vibration detection sensor based on the output signals of the plurality of vibration sensors, An active muffling device comprising: a driving unit that drives the vibration generating device based on a signal, wherein the vibration signal generating unit is one of the output signals of the plurality of vibration sensors and / or the output signal of the vibration sensor. One of the combined signals obtained by combining any of the above is selectively output depending on the operating state of the engine, and the noise detection sensor detects the vibration signal based on the selected vibration signal. And the noise to generate a vibration signal of the opposite phase, the active silencer of the vehicle running noise, characterized in that.