DE4305217A1 - Noise reduction system for interior of motor vehicle - has acoustic generators and processor control to dampen noise by phase controlled noise generation linked to actual noise - Google Patents

Abstract

The vehicle is fitted with acoustic sensors to monitor the noise inside the vehicle. Loudspeakers are driven by processor generated signals at preset phases to counteract the original noise and reduce the overall noise level to an acceptable range. Several loudspeakers are spaced about the vehicle, as are several detectors. The processor control identifies the engine noise from ignition pulses while vibrations are also monitored. The feedback between the generated noise and the pick-up on the detectors is identified and eliminated, only the original noise is corrected for by subsequent signals from the loudspeakers. ADVANTAGE - Improved noise reduction through use of several loudspeakers, improved comfort.

Description

The invention relates to a method and a system for Noise control for an automobile to periodic acoustic Reduce vibrations or noise, which generated by a vibration source, such as a machine will.

To be what "primary acoustic vibration in automobiles or noise "and from a primary source of vibration, for example a machine of an automobile, are generated to reduce noise control systems already known to artificially create what is called "secondary acoustic vibration "is designated by what vibration energy of the primary acoustic vibration or the primary acoustic noise is reduced or is wiped out.

Before describing the present invention in detail, reference is made to FIG. 1 to provide a brief description of the prior art noise control system described in Japanese Unexamined Patent Publication No. 1-501,344; this is intended to improve understanding of the present invention.

The prior art noise control system 30 includes, with reference to FIG. 1, a reference signal generator 31 , a controller 32 , a speaker 35, and a microphone 36 . The controller 32 has an internal adaptive filter 33 and a device 34 which operates as an operator according to the least mean square method (LMS) algorithm. The reference signal generator 31 monitors ignition pulses (IG pulses) which are generated by an ignition coil and which generate ignition sparks within the engine cylinder in order to ignite the fuel filling, whereby the pulses are assumed to be equivalent to the frequency of the engine vibrations. Corresponding to the ignition pulses, the reference signal generator 31 supplies a digital reference signal X to the controller 32 , in particular to the adaptive filter 33 . The adaptive filter 33 regulates the reference signal x with respect to the degree of amplification and phase, so as to supply the loudspeaker 35 with such a sound signal y ', which is reproduced by the loudspeaker 35 as sound d', ie as a second acoustic oscillation which is in phase with the first Noise d is reversed, ie to the primary acoustic vibration, such as machine noise, which it cancels.

The reference signal x is also sent to the LMS algorithm operator device 34 . At the same time, the adaptive filter 33 is supplied with an ambient noise signal e 'in a field which is formed by the first and second vibration sources, the level of which is representative of the energy level of ambient noise picked up by the microphone 36 and changes iteratively and optimizes its own filter coefficient f, to reduce the level of the ambient noise signal e '. The filter coefficient f converges to a specific value whenever the engine speed is unchanged, but it must be variable in response to changes in the engine speed.

The calculation of the LMS algorithm is carried out by the operator device 34 to vectors V-f₁, V-f₂,. . . , Vf _L iteratively optimize and renew the filter coefficient f of the adaptive filter 33 . The vector Vf is defined by the following general expression (1):

which is obtained as follows:

Vf _l (k) = [Vf _l1 (k) Vf _l2 (k). . . Vf _lI (k)] ^T ;
Vr _lm (k) = [Vr _lm1 (k) Vr _lm2 (k); . . . V- _lmI (k)] ^T
Vr _lmi (k) = Vh _lm ^T Vx (k-i + 1);
Vh _lm = [h _lm1 h _lm2 . . . h _lmJ ] ^T ;
Vx (k) = [x (k) x (k-1). . . x (k-J + 1)] ^T

where applies
L: number of speakers (first, second..., L-th,... L-th);
M: number of microphones (first, second..., M-th,... M-th);
V-f₁: vector of the filter coefficient by which the loudspeaker output of the lth loudspeaker is determined;
Vh _lm : vector of the filter coefficient by which the transmission characteristic between the lth loudspeaker and the mth microphone is determined;
x: the reference signal of the speaker, which contains the same frequency component as that of the noise;
r: the reference signal that is passed through the adaptive filter;
k: random time;
e _m : the output signal of the m th microphone;
µ: convergence coefficient;
I: the tap length of the V-f₁; and
J: the tap length of the vector Vh _lm .

A noise signal y ′ _l (k) to the lth speaker 35 is given by the following expression (2):

y ′ _l (k) = Vf _l (k) ^T · Vx ′ (k) (2)

which is obtained through

Vx ′ (k) = [x (k) x (kl). . . x (k-l + 1)] ^T

The speaker 35 reproduces the noise signal y ', which is obtained by the expression (2), as speaker noise d', which interferes with the ambient noise d around the speaker and extinguishes it. As can be seen from the above, the prior art noise control system is of the type of feed forward control.

These LMS algorithms from expression (2) of the prior art, which contain a number of terms, have to carry out a considerably high number of computations in a short period of time in order to obtain the vectors V-f 1 of the filter coefficient f of the adaptive filter 33 whose basis a noise signal y is determined to optimize interactively. Since the LMS algorithms of the prior art are intended for only one arrangement of loudspeakers and microphones, repeated calculations have to be carried out in noise control systems which contain a plurality of arrangements of loudspeakers and microphones. However, the operation of a processor of such a noise control system is too small to perform the calculations of the prior art LMS algorithm in a short period of time. As a result, loudspeakers and microphones in the vehicle cabin are limited in number in accordance with the working capacity of the processor used in the noise control system.

It is therefore an object of the present invention to provide a Noise control process and creating a system for it which allows an unlimited number of secondary acoustic Vibration sources and acoustic ambient To provide vibration sensors in a vehicle cabin.

The above object of the present invention is thereby achieved solved that a method of reducing energy the primary acoustic vibration from a primary Vibration source, such as a machine, is generated by a second acoustic vibration, which of second Vibration sources, such as one acted upon by a control signal acoustic speaker is generated, provided is. The control signal, in particular a vector of the Drive signal, is in accordance with that as the inner Noise from a monitoring device such as a microphone, monitored acoustic ambient vibration and a transmission characteristic, e.g. B. an impulse response, between the second vibration source and the acoustic vibration monitoring device, optimized iteratively.

An iterative optimization of a vector of a driver signal, that as a periodic acoustic vibration from the second vibration source is reproduced, accelerated strongly the number of algorithm calculations, a fraction the number of conventional LMS algorithm calculations, especially the use of processors with normal operating speeds to allow. Therefore a  unlimited number of speakers and microphones be recorded in the vehicle cabin so as to make noise in a wide area distributed over the vehicle cabin to reduce.

The above and other objectives of the properties of the present invention are detailed by the following Description with reference to preferred Understand executions better when related be considered with the accompanying drawings, in which the same reference numerals for the same or the same Elements have been used. In the drawings:

Fig. 1 is a schematic block diagram showing a noise control system of the prior art;

Fig. 2 is a schematic block diagram showing a noise control system according to a preferred embodiment of the present invention;

., In which the noise control system is contained Figure 3 is a schematic view showing a vehicle interior;

Fig. 4 is an illustration of a car in which a noise control system in accordance with another preferred embodiment of the present invention is contained; and

. 5 of the present invention is contained shows a representation of an automobile in which a noise control system in accordance with yet another preferred embodiment.

Referring to the drawing, and more particularly, to FIG. 2, there is shown a motor vehicle 21 , such as a four-seat vehicle with noise control system 10 therein, in accordance with a preferred embodiment of the present invention, having a multi-cylinder reciprocating engine 22 , such as an in-line four-cylinder -Piston piston engine as the primary vibration source that generates periodic acoustic vibrations (which are hereinafter referred to as primary vibrations). The primary vibrations are transmitted via the vehicle body and its equipment into the driver's or passenger cabin 25 of the vehicle 21 and generate air vibrations, e.g. B. acoustic noise in the vehicle cabin 25 . In the vehicle cabin 25 , a plurality, for example five in a four-seat vehicle, of loudspeakers 2 are arranged around the respective seats 26 and a multiplicity of microphones 3 , for example two, which are contained in the corresponding seats 26 , both of which are part of the Form noise control system 10 . Each loudspeaker 2 , which is referred to below as the secondary vibration source, artificially generates secondary acoustic vibrations or anti-noise vibrations. On the other hand, each of the microphones 3 records ambient noise around the seat 26 assigned to it. The noise control system 10 further includes a sensor 1 for monitoring the periodic vibration of the machine and a controller 4 for regulating the energy level of the secondary vibration generated by the loudspeaker 2 . The controller 4 has an internal processor, not shown, which is received by a large size integrated circuit (LSI) to iteratively optimize the energy level in accordance with the ambient noise and the transmission characteristics between the speakers 2 and the microphones 3 . The periodic vibration sensor 1, which is provided in connection with a primary coil 24a of the ignition coil 24, detects trigger pulses (IG) pulses which are sent to the engine 22 to the rotation period or the frequency of the machine to monitor the 22nd The periodic vibration sensor 1 then supplies a digital signal to the controller 4 , which is representative of the rotation period of the machine 22 . It is to be understood that the periodic vibration sensor 1 operates with greater accuracy and a lower voltage when it is provided in connection with the primary coil 24 a of the ignition coil 24 than when it is provided in connection with its secondary coil 24 b.

Each speaker 2 receives from the controller 4 a digital driver signal representative of a secondary acoustic vibration or an anti-noise vibration (which will be described in detail later) and reproduces it as a secondary acoustic vibration. The microphone 3 is contained in the seat 26 so as to collect environmental noise around the passenger sitting on its associated seat 26 , and it provides the controller 4 with a digital noise signal representative of the ambient noise. The term “ambient noise” as used in this application refers to a noise whose vibrational energy has been reduced and damped by the vibrational energy of the secondary acoustic vibration generated by the loudspeaker 2 .

The controller 4 , located near a lower portion of a front windshield 27 , and in particular its internal processor, generates the energy level of the second acoustic vibration that is necessary to reduce and cancel the ambient noise in the vehicle cabin 25 . This means that the internal processor of the controller 4 generates an energy level in accordance with the digital signal of the energy level of the ambient noise from the microphone 3 and, after the optimization of the energy level in accordance with the transmission characteristic between the loudspeaker 2 and the microphone 3, generates a digital driver signal Loudspeakers 2 delivers, which reproduces an energy level of the second acoustic vibration.

The noise control from the noise control system will be described in detail with reference to FIG. 3. Because the pairs of loudspeakers 2 and microphones 3 which are assigned to the corresponding seats 26 are functionally the same, only one pair of loudspeakers 2 and microphone 3 will be described for better clarity.

Referring to FIG. 3, the periodic vibration sensor 1 detects a rotation period or frequency of the engine 22 via the IG pulses generated by the ignition coil 24 and supplies a digital periodic signal (P _ER ), which is representative of the rotation period of the engine, to the controller 4 . The controller 4 regulates the period of a vector Vy of a speaker driver signal y in accordance with the period signal (P _ER ). At the same time, it transforms an impulse response h into a matrix form, which represents the transmission characteristic between the loudspeaker 2 and the microphone 3 , into a time sequence form (TS-h). This transformation is carried out by the internal processor. After the controller 4 has iteratively optimized the vector Vy on the basis of the time-sequential impulse response h and an ambient noise signal e from the microphone 3 , it transforms the vector Vy into a time sequence form (TS-y) and sends this as a driver signal y to the loudspeaker 2 . The loudspeaker 2 reproduces this as a secondary acoustic oscillation Z.

On the other hand, the microphone 3 records ambient noise as a result of the energy reduction of the first vibration d by the second acoustic vibration Z and sends an ambient noise signal e, which is representative of the vibration energy level of the ambient noise, to the controller 4 . The process from the iterative optimization of the vector Vy of a driver signal y to the reproduction of the driver signal y is carried out repeatedly so as to generate a suitable vector Vy of the driver signal y which is suitable for reducing the ambient noise signal e to a value of zero (0). to reduce.

The algorithm calculations performed in the process are described below.

Assuming a detection period δt of an ambient noise signal e provided by the microphone 3 and assuming that the impulse response h converges to zero (0) in a finite time Jδt, a kth sample of the ambient noise signal e, which becomes a current time k is detected, indicated by:

e (k) = d (k) + Z (k)
= D (k) + matrix H ^T · matrix y (k) (I)

With
Matrix h = [h₀ h₁ h₂. . . h _J-1 ] ^T ;
Matrix y (k) = [y (k) y (k-1) y (k-2). . . y (k-J + 1)] ^T ;

d (k): the component of the primary noise d to be contained in the ambient noise signal e (k);
Z (k): the component of the secondary acoustic oscillation Z which is contained in the ambient signal e (k); and
y (k): the kth sample of the control signal y.

thats why  

Because the primary vibration d at some time cycle Nδt is periodic, both must be secondary acoustic vibration Z and the driver signal y at the same time period Nδt as the primary vibration d be periodic.

Therefore:

where q = 0, 1, 2,. . .

so that the kth sample of the ambient noise signal e can be written as

e (k) = D (k) + Vh ^T × TS-y (k) (IV)

where applies  

where Q is a minimum number of integer q, which satisfy the condition J <(q + 1) N.

The (k + i) th sample of the ambient noise signal e, the at time (k + i) is indicated by

e (k + i) = d (k + i) + Vh ^T · TS-y (k + i)
D = (k + i) + TS-h (i) ^T · TS-y (k) (V)

where applies

TS-h (i) = [ _{i ′ i ′ + 1} . . . _{N + 1} ₀ ₁. . . _i′-1 ] ^T ;
TS-y (k + i) = [y (k + i ′) y (k + i′-1). . . y (k)
y (k + N-1) y (k + N-2). . . y (k + i ′ + 1)] ^T ;

i is an integer (0, 1, 2...); and
i ′ is an integer flag of i divided by N.

In expression (V) is the time k at which that Ambient noise signal e is detected only arbitrarily. If k is made zero (0) and i is replaced by k, then the expression (V) can be written as

e (k) = d (k) + TS-h (k) ^T · TS-y (0)
= D (k) + TS-h (k) ^T · Vy (VI)

where applies

Vy = [y (0) y (N-1) y (N-2). . . y (1)] ^T
+ [y₀ y _N-1 y _N-2 . . . y₁] ^T

If the evaluation function F is written as

F = E [e (k) ₂]
= E [d (k) + TS-h (k) ^T · Vy]
= E [d (k) ²] + 2 Vy ^T · E [d (k) TS-h (k)]
+ Vy ^T E [TS-h (k) · TS-h (k) T] · Vy (VII)

where E is an expected value or operation should and should refer to this, then the Gradient of the evaluation function F relative to the vector V-y indicated by

dF / dV-y = 2 E [d (k) TS-h (k)] + 2 E [TS-h (k) · TS-h (k) ^T ] Vy
= 2 E [TS-h (k) · {d (k) + TS-h (k) ^T · Vy}]
= 2 E [TS-h (k) · e (k)] (VIII)

The expression TS-h (k) · e (k) is used as the moment expected value of E [TS-h (k) · e (k)], the value of V-y, which indicates the speaker output vector that a time cycle Ndt (i.e. the number of elements) for the Has the minimum value of F by the following asymptotic Expression (IX) using the method of gradual acceptance iteratively optimized:

V-y (k + 1) = V-y (k) - µe (k) TS-h (k) (IX)

where µ / 2 is a convergence factor.  

In the case of only one pair of speakers and microphone, the asymptotic expression (IX) becomes from the following algorithm (X) substituted and simplified to set the vibrational energy of the counter noise that the Vibration energy of the primary noise d dampens, too correct:

y _{(k-j + QN) ′} (k + 1) = y _{(k-j + QN)} (k) - µ · e · (k) h _j (X)

where k ′ or (k-j + QN) ′ integer memory values of k and (k-j + QN) divided by N that are used be the lowest order of the primary vibration to be determined relative to the machine speed.

For this minimization, the processor of the controller 4 carries out the following sequential steps at a time k:

Step A1:
Input of a driver signal y (k) to the loudspeaker 2 ;

Step A2:
Input of an ambient noise signal e (k) from the microphone 3 ;

Step A3:
Assuming an integer N near the machine 22 rotation period multiplied by Ord / δdt or 1 / (Ord × dt), where Ord is an arbitrary coefficient to set the lowest order of ambient noise relative to the speed of rotation of the machine; and

Step A4:
Execution of the calculation of the asymptotic expression (X) for j from 0 to (J-1).

On the other hand, the optimized value of V-y of a driver signal of the lth loudspeaker, in the event that one Plurality of pairs of speakers and microphones are used is used to minimize the evaluation function  

through iterative calculations of the using the following asymptotic expression (XI) the method of decreasing steps achieved if

for one currently expected value of

used becomes:

with Vy _l = [y _{l 0} Y _{l N-1} y _{l N-2} . . . y _{l 1} ] ^T
TS-h _lm (k) = [ _{lm k ′ lm k ′ + 1} . . . _{lm N + 1 lm 0 lm 1} . . . _{lm k′-1} ] ^T
h _{lm 0} = _{lm k ′ + 1} + _{lm N} +. . . + _{ln the QN}
h _{lm 1} = _{lm 1} + _{lm N + 1} +. . . + _{ln QN + 1}
.
.
.
h _{lm J-QN-1} = _{lm J-QN-1} + _{lm J- (Q-1) N-1} +. . . + _{ln J-1}
h _{lm J-QN} = _{lm J-QN} + _{lm J- (Q-1) N} +. . . + 0
h _{lm N-1} = _{lm N-1} + _{lm 2N-1} +. . . + 0
where applies
y _{lk ′} : the loudspeaker signal of the first loudspeaker at time k;
e _m : the ambient noise signal from the m th microphone;
h _{lm j} : value of the impulse response between the first loudspeaker and the mth microphone at a later point in time;
L: number of speakers;
M: number of microphones; and
J: an integer value indicating that the impulse response of all combinations of speakers and microphones converges to zero within a finite time jdt.

Hence the asymptotic expression (IX) can be written are considered

At a time k, the processor of the controller 4 carries out the following sequential steps:

Step B1:
Input of control signals y _{1k ′} (k), y _{2k ′} (k) _,. . . , y _{Lk '} (k) each for the first, second,. . . , Lth speaker 2 ;

Step B2:
Input of ambient noise signals e₁ (k), e₂ (k),. . . e _M (k) for the first, second,. . . Mth microphone 3 ;

Step B3:
Assuming an integer N near the value of a rotation period of the machine 22 multiplied by Ord / dt or 1 / (Ord × dt), where Ord is an arbitrary coefficient for setting the lowest order of ambient noise relative to the rotation speed of the machine; and

Step B4:
Perform the calculation of the asymptotic expression (XII) for l from 1 to L and j from 0 to (J-1).

Furthermore, the optimized value of V-y, which is the output vector of the first speaker indicates to minimize the evaluation function

by iteratively calculating the following asymptotic expression (XIII) using the descending step method if α TS-h _{lk ′} (k) · e _{k ′} (k) for a currently expected value of

is used:

Vy _l (k + 1) = Vy _l (k) = µ · α TS-h _{lk ′ ′} (k) · e _{k ′ ′} (k) (XIII)

where k ′ is the sum of an integer memory value of k divided by M and one (1) and α is an arbitrarily fixed constant.

Hence the asymptotic expression (IX) can be written are considered

y _{l (k-j + QN) ′} (k + 1) = y _{l (k-j + QN) ′} (k) - µ · α · e _{k ′ ′} (k) · h _{lk ′ ′ j} (XIV)

Calculations for the asymptotic expression (XIII) are performed faster than for the asymptotic expression (XI). The sequential steps carried out by the processor of the controller 4 at time k are as follows:

Step C1:
Input of loudspeaker _signals y _{1k ′} (k), y _{2k ′} (k) _,. . . , y _{Lk ′} (k) to the first, second. . . , Lth speaker 2 ;

Step C2:
Input of ambient noise signals e _{k ′ ′} (k) from the k ′ ′ - th microphone 3 ;

Step C3:
Assume an integer N near the value of a machine 22 rotation period multiplied by Ord / dt or 1 / (Ord × dt), where Ord is an arbitrary coefficient to set the lowest order of ambient noise relative to the speed of rotation of the machine ; and

Step C4:
Perform the calculation of the asymptotic expression (XII) for l from 1 to L and j from 0 to (J-1).

Hence the calculation of the algorithm by iterative Calculations of the asymptotic expressions (IX), (XI) or (XIII) or their simplified substitution terms (X), (XII) or (XIV) performed in this way the Accelerate calculation of the speaker signal.

Alternatively, the speakers can be hydraulic Actuating means replaced as a source of secondary vibrations will.

In Fig. 4, an actuator 28 is provided between a machine 22 and a machine mounting 21 a so as to hydraulically support the machine 22 . The hydraulic actuator 28 , which is shown only schematically, contains a plurality of cylinder treasures (not shown), which are attached to the machine mounting 12 a, and pistons (not shown), which are attached to the machine, and a hydraulic circuit (not shown); all of these elements can take any known form. As the machine 22 swings, it reciprocates the respective pistons within the respective cylinders. Periodic vibrations of the pistons are monitored by a sensor 1 . A controller 4 controls the hydraulic circuit based on the periodic vibration sensed by sensor 1 so as to draw hydraulic oil from the cylinders when the pistons are pushed down by the engine and to push hydraulic oil into the cylinders when the pistons are down be pulled up. During this control, a driver signal, by means of which the hydraulic circuit is controlled, is iteratively optimized in order to reduce ambient acoustic vibrations in the vehicle cabin 25 .

In addition to providing the hydraulic actuators a vehicle acceleration sensor can be provided by which the microphone is replaced.

In Fig. 5, a vehicle acceleration sensor 29 is provided in Vebindung with a machine 22 to monitor as the acceleration of the machine 21 as a periodic engine vibration, ie as the primary periodic oscillation. After the primary oscillation has been enolized, the controller 4 supplies a driver signal with which the hydraulic circuit is controlled in order to effect the injection of hydraulic oil into the cylinders and the extraction of hydraulic oil from the cylinders. In such a way, the energy of periodic vibrations of the machine 22 is absorbed so as to isolate the transmission of the machine vibration to the vehicle body via the machine mount 21 a. A plurality of hydraulic actuators 28 or the vehicle acceleration sensor 29 may be included in the vehicle 21 .

Although the present invention has been described in detail with reference to FIG a preferred embodiment thereof has been described is, different other designs can Surrender specialist. Such other designs and variants fall within the scope and spirit of the invention and are intended to be covered by the following claims.

Claims (16)

1. Noise control system for reducing acoustic vibrations, which are generated by a primary vibration source, such as a machine for a motor vehicle, with
periodic vibration sensor means for periodically monitoring acoustic vibrations generated by the primary vibration source;
secondary vibration sources driven by a drive signal to generate secondary acoustic vibrations by which the energy of the periodic acoustic vibration is reduced;
acoustic vibration sensor devices for monitoring acoustic ambient vibrations in their environment; and
Control devices for regulating the driver signal in accordance with the periodic acoustic vibration and for iteratively optimizing the driver signal in accordance with the acoustic ambient vibration and a transmission characteristic between the secondary vibration source and the acoustic vibration sensor device in order to reduce the acoustic ambient vibration in its energy level. 2. Noise control system according to claim 1, characterized, that the control device has an internal processor which is in accordance with an algorithm for iterative optimization of the driver signal is working. 3. Noise control system according to claim 2, characterized, that the internal processor has a vector of the driver signal optimized iteratively. 4. Noise control system according to claim 3, characterized, that the internal processor the vector of the driver signal after optimization in a time sequential Form transformed. 5. Noise control system according to claim 4, characterized, that the internal processor the transfer characteristic in a time sequential form. 6. A noise control system according to claim 1, characterized, that an impulse response in a time sequential form is used for the transmission characteristic.   7. A noise control system according to claim 1, characterized, that the secondary vibration source has at least one Speakers. 8. A noise control system according to claim 1, characterized, that the acoustic noise sensor at least one Has microphone. 9. A noise control system according to claim 1, characterized, that an impulse response for the transmission characteristic is used. 10. A noise control system according to claim 1, characterized, that the periodic vibration sensor device one Has pulse sensor in conjunction with a Ignition coil of the machine is provided to the time cycle of ignition pulses generated by the ignition coil detect. 11. A noise control method for a motor vehicle, in which primary acoustic vibrations generated by a primary vibration source such as a machine are reduced in their energy by secondary acoustic vibrations generated by secondary vibration source devices driven by a drive signal which in Is optimized in accordance with the acoustic ambient vibration in an acoustic field, which is generated by the primary vibration source and the secondary vibration source, by means of an acoustic vibration monitor, the method for noise control comprising the following steps:
Monitoring periodic acoustic vibrations generated by the primary vibration source;
Controlling a period of the driver signal in accordance with the periodic acoustic vibration; and
iteratively optimizing the driver signal in accordance with the ambient acoustic vibration and a transmission characteristic between the secondary vibration source and the acoustic vibration sensor in order to reduce the acoustic ambient vibration in its energy. 12. A noise control method for an automobile to reduce primary acoustic vibrations generated by a primary vibration source, such as a machine, by secondary acoustic vibrations in their energy generated by secondary vibration source devices driven by a drive signal that is in accordance is optimized with the acoustic ambient vibration in an acoustic field, which is generated by the primary vibration source and the secondary vibration source, by means of an acoustic vibration monitor, the method for noise control comprising the following steps:
Monitoring periodic acoustic vibrations of the primary acoustic vibration source;
Regulating the period of a vector of the drive signal in accordance with the periodic acoustic oscillation;
iteratively optimizing the vector in accordance with the acoustic ambient vibration and an impulse response between the secondary vibration source and the acoustic vibration monitoring in order to reduce the acoustic ambient temperature in its energy. 13. A method for noise control according to claim 12, featured through the further step of optimizing the driver signal through iterative calculations in accordance with an algorithm. 14. A method for noise control according to claim 13, featured through the further step of converting the vector the driver signal in a time sequential form of optimization. 15. A method for noise control according to claim 14, featured through the further step of converting the impulse response in a time sequential form. 16. A method for noise control according to claim 12, featured through the further step of monitoring the periodic acoustic vibration by monitoring of firing pulses from one in conjunction with the Engine provided ignition coil are generated.