JPH07199967A - Adaptive active silencer for vehicle interior sound - Google Patents

Abstract

PURPOSE:To obtain sufficient sound elimination effect even if a factor which varies a transmission system is generated after the shipment from the factory by identifying control system acoustic transmission characteristics during the operation of the adaptive active sound elimination device for in-cabin sound and updating the identified control system acoustic transmission characteristics at specific timing. CONSTITUTION:This device is equipped with a control means 4 which uses an adaptive filter to receive the reference signal from a reference signal generating means 1 and the control point signal from a control point signal detecting means 2-1 and then control the sound wave signal outputted from a secondary sound source 3 so that the control point signal becomes minimum, and provided with a control system acoustic characteristic identifying means 5-3 which identifies control system acoustic transmission characteristics during the operation of the device and a control system acoustic transmission characteristic updating means which updates the control system acoustic transmission characteristic identified by the control system acoustic transmission characteristic identifying means 5-3 for the control means 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adaptive active silencer for vehicle interior sound. In general, in the indoor muffled noise of 200 Hz or less, which has a large effect on the occupant noise in the vehicle interior noise, the panel vibration radiation noise caused by the engine rotation vibration is dominant. , Is an important issue related to the strength problem.

[0002]

2. Description of the Related Art Conventionally, an active noise canceller using an adaptive filter has been proposed in order to reduce the muffled noise in the room. That is, in such an active noise canceller, a sound having an equal amplitude and a reverse phase to the vehicle interior noise is emitted from the secondary sound source by using an adaptive filter so that the signal at the control point in the vehicle interior is minimized. It is in control.

Further, the characteristics of the sound deadening transmission system are measured in advance, and the sound deadening control is performed by using the measured characteristic information of the sound deadening transmission system as correction information of the reference signal.
A system in which the system is operated stably after the start of control has also been proposed (see Japanese Patent Laid-Open No. 4-308899).

[0004]

However, in such a conventional means, since the control system acoustic transfer function such as the muffling transfer system is set at the time of factory shipment, the transfer system is changed after the factory shipment. Factors such as microphone, speaker, amplifier, frequency characteristic change of controller for active noise canceller, change of number of passengers,
Changes in sound absorption in the passenger compartment, including clothing of passengers, changes in the vehicle interior sound and sound field due to opening and closing of doors and windows, changes in the vehicle body transmission system due to large luggage placed in the passenger compartment, etc. The adaptive filter must bear the load. Therefore, in consideration of the worst case, the muffling volume must be reduced (the control amount is small), which may result in insufficient muffling effect.

Particularly, in the case of using an adaptive filter with a small number of taps, control corresponding to the above change cannot be performed, and there is a fear that the silencing effect is significantly reduced. The present invention has been made in view of such a problem, and in an adaptive active silencer using an adaptive filter, the control system acoustic transfer characteristics are identified during the operation of the device, and the identified control system acoustic transfer is performed. It is an object of the present invention to provide an adaptive active silencer that can update its characteristics at a required timing so that a sufficient silencing effect can be obtained even if a factor that changes the transmission system after factory shipment occurs. To do.

[0006]

Therefore, the adaptive active noise canceling system for vehicle interior sound according to the present invention comprises a reference signal generating means for generating a reference signal due to a noise source of the vehicle and a control point in the vehicle interior. Control point signal detecting means for detecting a signal of the control signal and a secondary sound source for outputting a sound wave signal to the vehicle interior, and a reference signal from the reference signal generating means and a control point from the control point signal detecting means. Signal and a control means using an adaptive filter for controlling the sound wave signal output from the secondary sound source so that the control point signal is minimized. In a silencer, during operation of the device, a control system acoustic transfer characteristic identifying means for identifying a control system acoustic transfer characteristic, and a control system acoustic transfer characteristic identified by the control system acoustic transfer characteristic identifying means to the control means. Control system sound transmission to be updated It is characterized in that the sex updating means provided.

[0007]

In the above-mentioned adaptive active noise canceling system for vehicle interior sound of the present invention, the control means using the adaptive filter receives the reference signal from the reference signal generating means and the control point signal from the control point signal detecting means. 2 so that the control point signal is minimized.
Although the sound wave signal output from the next sound source is controlled, the control system acoustic transfer characteristic identifying means identifies the control system acoustic transfer characteristic while the control system acoustic transfer characteristic identifying means further operates. The control system acoustic transfer characteristic identified by the control system acoustic transfer characteristic identifying means is updated to the control means.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. (A) Description of First Embodiment FIGS. 1 to 6 show an adaptive active noise canceling system for vehicle interior sound as a first embodiment of the present invention. FIG. 1 is a block diagram of its essential parts, and FIG. A system block diagram thereof, FIG. 3 is a block diagram showing details of a system control unit, FIG. 4 is a block diagram explaining a control algorithm of the present apparatus, and FIG.
Is a diagram for explaining the M-sequence noise signal level, and FIGS. 6 and 7 are flowcharts for explaining the control procedure thereof.

In the first embodiment, as shown in FIGS. 1 to 3, control point signal detecting means for detecting a signal at a control point (evaluation point) in the passenger compartment 200 is provided. The control point signal detecting means is provided for the driver seat 201 in the vehicle interior 200.
It is configured as a control microphone (for example, a simple condenser microphone) 2-1 provided on the headrest of the. More specifically, the control microphone 2-1 is provided in a portion of the headrest near the center of the vehicle compartment via a rubber case.
The reason why the control microphone 2-1 is provided in the portion of the headrest near the center of the vehicle compartment in this way is to reduce the influence of the reflection of the glass and the like and increase the effective area.

The control point signal detected by the control microphone 2-1 is amplified by a microphone amplifier (amplifier) 12 provided inside the seat back. Furthermore, a speaker (cancelling speaker) 3 as a secondary sound source that outputs a sound wave signal (secondary source signal) toward the vehicle interior 200 is provided. In this case, the speaker 3 is a rear seat of the vehicle interior 200. At the rear end of 203, the trunk is arranged at a position where it can be used as a back cavity. That is, this speaker 3
The rear seat 203 is attached to a partition wall (speaker mounting plywood) on the rear surface of the seat back so that the vibration surface faces the opening that opens when the armrest of the rear seat 203 is tilted.

Further, a reference signal generating means 1 for generating a reference signal due to a noise source of the vehicle is provided. The reference signal generating means 1 is, for example, an acceleration sensor or an engine for detecting vibration of the engine 100. A means (electronic control unit (ECU)) for detecting a pulse (ignition pulse) can be considered. In addition to this, as the reference signal generating means 1, a road noise detecting microphone or an accelerometer for detecting road noise, an exhaust sound detecting microphone for detecting exhaust noise, a wind noise detecting microphone for detecting wind noise, and the like are used. Conceivable.

The above-mentioned ECU receives a detection signal from an engine speed sensor, an engine load sensor, etc., and outputs a signal for ignition timing control of the engine 100 and a signal for fuel supply control (air-fuel ratio control). The output is a publicly known one including a microprocessor, a memory and the like, and normally, an engine pulse (ignition pulse) can be easily taken out from the ECU.

By the way, the system control unit 13 is arranged in the trunk room. And
This system control unit 13 is shown in Figs.
As shown in FIG.
The detection signal from -1 is input and the speaker 3
A secondary source signal is output via the speaker amplifier 7.

This system control unit 13
Is a numerical processor 40, ROM 41, RAM 4
2, digital signal processor (hereinafter referred to as DSP) 43, status control register (hereinafter referred to as S)
CR) 44, clock generator 45, low-pass filters 51, 52, 53, A / D converters 61, 62, D /
A converter 63, timing generator 8, serial port 1
0, and the numerical operation processor 40, RO
M41, RAM42, DSP43, SCR44, A / D
The converters 61, 62 and the D / A converter 63 are connected via an optical fiber 15 with a photoelectric converter (O / E) and an electro-optical converter (E / O).

Then, these numerical arithmetic processors 4
0, ROM41, RAM42, DSP43, SCR4
4, the clock generator 45 constitutes the main controller 4. Here, the numerical calculation processor 40 is a DSP used for calculation for silencing control (active noise cancellation).
On the bus of this numerical operation processor 40, ROM4
1, the RAM 42, the DSP 43, and the SCR 44 are arranged.

The ROM 41 stores the characteristic information of the muffler transmission system [the transmission system from the speaker (secondary sound source) 3 to the control point in the vehicle interior 200 (position where the control microphone 2-1 is installed), the speaker 3, the amplifier 7, the microphone. 2-1 including the frequency characteristic (time delay) of 2-1] and the like are stored. The RAM 42 stores a control program, the DSP 43 functions as a digital filter processor, and the SCR 44 is a D
It controls address allocation between the SP 43 and the numerical operation processor 40.

The clock generator 45 generates an operation clock for the numerical processor 40. Low-pass filters 51, 52, 53, A / D converters 61, 6
2, the D / A converter 63 is an interface between the reference signal generating means 1, the control microphone 2-1 and the speaker 3 and the main control section 4, and the analog signal detected by the reference signal generating means 1 is a low-pass signal. After being filtered by the filter 51, A / D
It is converted into a digital signal by the converter 61, and the main control unit 4
The analog signal input to the control microphone 2-1 is further filtered by the low-pass filter 52, and then the analog signal A
The signal is converted into a digital signal by the D / A converter 62 and input to the main control unit 4, while the secondary source signal from the main control unit 4 is converted into an analog signal by the D / A converter 63. After that, it is filtered by the low-pass filter 53 and output to the speaker 3.

The low-pass filter used is one that cuts the band output above the maximum control frequency in order to prevent aliasing from the speaker 3. The timing generator 8 includes A / D converters 61 and 62 and a D / A converter 6
A timing pulse for determining the input / output timing of No. 3 is generated, and the numerical arithmetic processor 40 starts / stops by writing a command in the control register.

The serial port 10 is an external terminal for connection with an external computer. It should be noted that the control program of this system is booted by the on-board ROM when the power is turned on, so that the system operates in a stand-alone manner. By the way, in this embodiment, the main control section 4 of the system control unit 13 receives the reference signal from the reference signal generating means 1 and the control point signal detected by the control microphone 2-1 and outputs the control point signal. It is configured as a control means using an adaptive filter so as to control the sound wave signal output from the speaker 3 so as to be minimum (preferably 0). Further, in this example, the main control unit 4 is adapted to perform the muffling control using an adaptive filter using an algorithm based on the least square error estimation method (LMS method).

Further, in this embodiment, before the silencing control is performed, the characteristics of the silencing transmission system including the transmission system from the speaker 3 to the control point in the vehicle interior 200 (position where the control microphone 2-1 is installed) in advance ( Transfer function) D is measured. This measurement is performed as follows. That is, the speaker 3 outputs an M-series random sound (M-series noise: white noise),
The characteristic D of the muffler transmission system is measured by detecting this with the control microphone 2-1.

After that, the measured muffling characteristic information of the muffler transmission system is used as the correction information of the reference signal to perform the muffling control by the main control section 4. That is, the reference signal is filtered by a filter having the characteristic information D ′ of the measured muffler transmission system, and from this and the control point signal detected by the control microphone 2-1, a filter by the LMS method is used. The coefficient is updated.

Further, in the present embodiment, as shown in FIG. 1, the control system acoustic transfer characteristic identifying means for identifying the control system acoustic transfer characteristic during operation of the apparatus and the control system acoustic transfer characteristic identifying means are used for identification. Control means 4 for controlling the acoustic transfer characteristics of the control system
The control system acoustic transfer characteristic identification updating means 5 having both functions of the control system acoustic transfer characteristic updating means for updating is provided.

That is, the control system acoustic transfer characteristic identifying and updating means 5 includes the M-sequence noise source 5-1 and the variable attenuator 5-.
2. An identification control means 5-3 for identifying the control system acoustic transfer characteristics by using an adaptive filter using an algorithm based on the least square error estimation method (LMS method) is provided. And
The M-sequence noise from the M-sequence noise source 5-1 whose output level is adjusted by the variable attenuator 5-2 is output from the speaker 3 and is also supplied to the identification control means 5-3 as a reference signal. Has become. The output M-sequence noise level is lower than the noise level observed in the vehicle (see the solid-line spectrum characteristic a in FIG. 5), that is, the M-sequence, as shown by the dotted line spectrum characteristic b in FIG. The noise level is set to be the background noise level with respect to the noise level observed in the vehicle. This way,
Even if the M-sequence noise is constantly output, the occupant cannot hear the noise based on the M-sequence noise.

The error signal from the control microphone 2-1 is input to the identification control means 5-3. Then, while the apparatus is in operation, M-sequence noise is always output, and this is detected by the control microphone 2-1 so that the identification control means 5-3 measures the characteristic D of the silence transmission system and the control system. The acoustic transfer characteristics are identified.

Further, when the characteristic control means 5-3 measures the characteristic D of the muffler transmission system to identify the control system acoustic transmission characteristic, when the error signal becomes larger than a predetermined value at every predetermined period, or The identified control system acoustic transfer characteristics are irregularly transferred to the control means 4 and copied (copied) to be updated. As a result, for example, changes in frequency characteristics of the microphone, speaker, amplifier, controller for active noise canceller, changes in the number of passengers,
Even if changes in sound absorption in the passenger compartment, including clothing of passengers, changes in the sound and sound field inside the vehicle due to opening and closing of doors and windows, changes in the vehicle body transmission system due to large luggage in the room, etc., are always suitable. Since the control system has an acoustic transfer characteristic, a sufficient silencing effect can be obtained even when an adaptive filter with a small number of taps is used.

Next, the basic algorithm of this system will be described in detail. First, the mute control (active noise control) of this system is Filtered-X LMS.
An adaptive FIR filter using an algorithm is used. A basic block diagram is shown in FIG. In this block diagram, T is the characteristic of the vehicle body transmission system (including the acoustic transmission characteristic from the noise source to the control point (control microphone 2-1 installation position)),
W is an adaptive FIR filter, D is a characteristic of a sound transmission system [including sound transmission characteristics from the secondary sound source (speaker 3) to the control point (installation position of control microphone 2-1)], D'is a model of D, LMS Is the LMS algorithm.

This system uses the reference signal X from the noise source.
Input (t) and convolve with FIR to obtain output Y (t). Y (t) = ΣW (i) X (t−i) ··· (1) In addition, regarding the formula (1), the summation is performed for i = 0 to N−1.

When the system outputs -Y (t), the error signal E at the control point is obtained due to the transfer characteristic of the sound field. E (t) = T (z) X (z) -D (z) Y (z) (2) Further, in order to maintain the causal relationship between the reference signal X (t) and the error signal E (t). Filter X (t) and d
Find (t).

D (t) = ΣD ′ (i) X (t−i) ··· (3) It should be noted that the equation (3) is also adapted to take the total sum for i = 0 to N−1. . Then, the filter coefficient W (i) is updated using the LMS algorithm from the error signals E (t) and d (t). That is, Wn (i) = Wo (i) + kE (t) d (t-i)
(I = 0 to N−1) (4) where Wn (i) is the updated filter coefficient, Wo
(I) is a filter coefficient before updating, and k is an updating coefficient.

As a result, the filter converges on the optimum filter that minimizes the error signal. Further, the error E is determined by the reference signal X, the filter coefficient W, and the silence transmission system characteristic D. That is, it is necessary to consider D in the preceding stage of the LMS algorithm used to maintain the causal relationship between the input data and the error. Therefore, in this system, the adaptive algorithm is the Filtered-X-LMS algorithm, and the D is identified not only before the adaptive control is started but also during the operation of the apparatus. If D is identified while the device is operating,
It is updated by transferring and copying (copying) the identified control system acoustic transfer characteristics to the control means 4 at predetermined intervals or when the error signal becomes larger than a predetermined value or at irregular intervals.

In this way, W will converge on the Wiener filter if a sufficient time elapses after the start of control, and if it is ideal, then W =-(T / D). That is,
W will perform forward modeling of T and inverse modeling of D at the same time. At this time, when the input noise signal is X, the output of T is TX, the output of W is represented by (-TX / D), and the output of D is (-TX /
D) .D = -TX.

That is, the error signal E becomes 0 at the addition point (see P) which is the evaluation point (control point). Here, when T and D are expressed in polar coordinates, they are expressed by W = (T / D) exp [-j (θt−θd)] ··· (5). Considering the actual machine model, the engine intake sound measured in the vehicle compartment is caused by the engine rotation (vibration), and is therefore always larger than the delay of T and (θt-θ
d) shows a positive value. In other words, W is considered to be controllable because it becomes a delay element.

Next, the control flow in this system will be shown in FIGS. 6 and 7. First, the identification procedure of D performed before the start of the adaptive control or during the operation of the apparatus will be described with reference to FIG. . In step A1, A / D, D / A
Initialize conversion, control register, counter, etc., and start A / D conversion, and then step A2
Then, an M-sequence signal is generated. After that, step A3
Then, the adaptive filter calculation is performed, the D / A conversion is further started, and the operation of updating the adaptive filter coefficient is repeated in step A4 to identify the characteristic of the muffling transmission system.

After that, the operation as shown in FIG. 7 is performed. That is, first, as shown in step B1, A / D, D / A conversion, control registers, counters, etc. are initialized, and the measured characteristic information of the muffler transmission system [initial impulse response: this information is adaptive control Is read before the start of (1) or while the apparatus is in operation (every predetermined cycle or when the error signal becomes larger than a predetermined value or irregularly), and then a reference signal is generated in step B2.

After that, A / D and D / A conversion is started, adaptive filter calculation is performed, and adaptive filter coefficients are updated (steps B3 to B5). Further, by repeating the same processing operation, the convolution operation is performed by the adaptive FIR filter, the coefficient is updated by the LMS method until the error signal becomes equal to or lower than a predetermined level, and the output signal is output to the speaker 3.

Since the number of taps of the adaptive filter and the noise reduction amount are in a substantially linear proportional relationship,
The larger the number of taps, the greater the amount of effect, but D to use
Since it is necessary to determine the relationship between the SP performance, the number of SPs, and the cost, for example, the number of taps is 256.
Alternatively, 128 is set. Further, in the silencing control using the adaptive filter, it is necessary to control at the sampling frequency at which a waveform of at least ¼ wavelength exists between the number of taps used, and therefore the sampling frequency is determined accordingly.

As described above, in the adaptive active silencer using the adaptive filter, the control system acoustic transfer characteristics are identified during the operation of the apparatus, and the identified control system acoustic transfer characteristics are updated at a required timing. Therefore, even if there is a factor that changes the transmission system after factory shipment, a sufficient silencing effect can be obtained. Then, using the measured characteristic information of the muffler transmission system as the correction information of the reference signal,
Since the mute control is performed by the system control unit 13, the system can be operated more stably after the control is started.

(B) Description of Second Embodiment FIG. 8 is a block diagram of a main part of an adaptive active noise reduction system for vehicle interior sound as a second embodiment of the present invention. In FIG. 8, the same as FIG. The reference numerals indicate almost the same parts. By the way, in the second embodiment, while the apparatus is in operation, M series noise is always output, and the control microphone 2-1 detects the noise to measure the characteristic D of the silence transmission system by the identification control means. Therefore, it does not identify the acoustic transfer characteristics of the control system.If the error signal becomes larger than a predetermined value and the condition that the passengers do not feel uncomfortable even if the silencing control is stopped, an adaptive filter is used. The muffling control is temporarily stopped, M-sequence noise is output, and this is detected by the control microphone 2-1 so that the control means 4 measures the characteristic D of the muffling transmission system to transmit the control system acoustic transmission. The characteristic is identified and the identified characteristic is updated.

Therefore, in the second embodiment, as shown in FIG. 8, the switch means 71 for switching between the reference signal line and the M-series noise line from the M-series noise source 5-1.
And a switching control means 72 for controlling the switching of the switching means 71 are added to the reference signal input system of the adaptive filter. Here, the switching control means 72 sets the switching means 71 to the reference signal line side unless the error signal becomes larger than a predetermined value and the condition that does not make the occupant uncomfortable even when the silencing control is stopped is established. If the error signal becomes larger than the predetermined value and the condition that does not make the occupant uncomfortable even when the silencing control is stopped is satisfied, the switch means 71 is controlled to switch to the M-sequence noise line side. It is a thing.

Then, in this way, the switch means 71
After switching to the M-series noise line side to identify the control system acoustic transfer characteristic, the identified characteristic is updated. Therefore, also in the case of the second embodiment, the control system acoustic transfer characteristic identifying means for identifying the control system acoustic transfer characteristic and the control system acoustic transfer identified by the control system acoustic transfer characteristic identifying means during the operation of the apparatus. The control system acoustic transfer characteristic updating means for updating the characteristics to the control means 4 is provided.

The fact that the noise reduction control (active noise control) is performed by the adaptive FIR filter using the Filtered-X LMS algorithm is the same as in the first embodiment described above, and therefore detailed control for noise reduction is performed. The description of the algorithm is omitted. As a result, according to the second embodiment, the control system acoustic transfer characteristic is identified when the error signal becomes larger than the predetermined value and the condition that does not make the occupant unpleasant even when the silencing control is stopped is established. However, since the identified control system acoustic transfer characteristics are updated, for example, changes in frequency characteristics of a microphone, a speaker, an amplifier, a controller for an active noise canceller, a change in the number of occupants, clothes of the occupants, etc. Even if there is a change in force, a change in the vehicle interior sound or sound field due to the opening or closing of doors or windows, or a change in the vehicle body transmission system due to a large baggage being placed in the room, a sufficient noise reduction effect can be expected.

Further, since the adaptive filter for identifying the characteristic can be shared with the adaptive filter for the silencing control, the system can be simplified and the DSP scale can be reduced, thereby reducing the cost and downsizing. It can also contribute to (C) Others The present invention can also be applied to a system having a plurality of control points. In this case, the control system acoustic transfer characteristics are identified for each control system, and the respective control systems are identified. It is necessary to update the control system acoustic transfer characteristics.

As a secondary sound source, the speaker 3 is arranged at the rear end of the rear seat 203 of the vehicle compartment 200 at a position where the trunk room can be used as a back cavity as described above, and a vibration exciter is provided on the roof panel. It is possible to install these by installing a vibrator on the floor panel.
It may be the next sound source. Further, the connecting lines of the A / D converter, the D / A converter, the ROM, the RAM, the DSP, etc. may of course be copper wires.

[0044]

As described above in detail, according to the adaptive noise canceling system for the vehicle interior sound of the present invention, the reference signal generating means for generating the reference signal due to the noise source of the vehicle and the control of the vehicle interior. A control point signal detecting means for detecting a signal at a point and a secondary sound source for outputting a sound wave signal to the vehicle interior are provided, and a reference signal from the reference signal generating means and a control signal from the control point signal detecting means are provided. Adaptation of vehicle interior sound, comprising control means using an adaptive filter for receiving the control point signal and controlling the sound wave signal output from the secondary sound source so that the control point signal is minimized. Type active silencer, the control system acoustic transfer characteristic identifying means for identifying the control system acoustic transfer characteristic during operation of the device, and the control system acoustic transfer characteristic identified by the control system acoustic transfer characteristic identifying means Control system sound transmission to be updated for Since the characteristic updating means is provided, the control system acoustic transfer characteristics can be identified during operation of the apparatus, and the identified control system acoustic transfer characteristics can be updated at a required timing. Even if a factor that changes the transmission system later occurs, there is an advantage that a sufficient silencing effect can be expected.

[Brief description of drawings]

FIG. 1 is a block diagram of an essential part of a first embodiment of the present invention.

FIG. 2 is a system block diagram showing a first embodiment of the present invention.

FIG. 3 is a block diagram showing details of a system control unit according to the first embodiment of the present invention.

FIG. 4 is a block diagram illustrating a control algorithm of this device.

FIG. 5 is a diagram illustrating an M-sequence noise signal level.

FIG. 6 is a flowchart illustrating a control procedure of the first embodiment of the present invention.

FIG. 7 is a flowchart illustrating a control procedure of the first embodiment of the present invention.

FIG. 8 is a block diagram of an essential part of a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reference signal detection means 2-1 Control microphone (control point signal detection means) 3 Speaker (secondary sound source) 4 Main control section 5 Control system acoustic transfer characteristic identification update means 5-1 M series noise source 5-2 Variable attenuator 5-3 Identification control means 7 Amplifier 8 Timing generator 10 Serial port 12 Microphone amplifier 13 System control unit 15 Optical fiber 40 Numerical operation processor 41 ROM 42 RAM 43 DSP 44 SCR 45 Clock generator 51, 52, 53 Low pass filter 61, 62 A / D converter 63 D / A converter 71 Switch means 72 Switching control means 100 Engine 200 Vehicle compartment 201 Driver's seat 203 Rear seat

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Claims (1)

[Claims] 1. A reference signal generating means for generating a reference signal originating from a noise source of a vehicle, a control point signal detecting means for detecting a signal at a control point in the vehicle interior, and a sound wave signal directed to the vehicle interior. A secondary sound source for receiving the reference signal from the reference signal generating means and the control point signal from the control point signal detecting means, and from the secondary sound source to minimize the control point signal. An adaptive active noise suppressor for vehicle interior sound, which is equipped with control means using an adaptive filter to control the sound wave signal to be output. A vehicle provided with transfer characteristic identifying means and control system acoustic transfer characteristic updating means for updating the control system acoustic transfer characteristic identified by the control system acoustic transfer characteristic identifying means with respect to the control means. Adaptive active of room sound Silencer.