Noise reduction device, vehicle, and noise reduction method

Abstract

The problem is, in a noise reduction system that uses speakers and microphones corresponding to respective seats of a vehicle to reduce the noise of each seat, to invalidate the output of the speaker of a seat without an occupant and to improve the noise reduction effect. The solution is that the noise reduction device uses speakers and microphones corresponding to respective seats of the vehicle to reduce the noise for each seat, and the noise reduction device includes: a signal processing unit that generates a cancellation sound for reducing noise at the position of the ear of an occupant on a specified seat by using a set auxiliary filter; an operation setting unit that sets the operations of the speaker and the microphone corresponding to a seat without an occupant among the seats of the vehicle to be invalid; and an auxiliary filter setting unit that changes the set value of the auxiliary filter used by the signal processing unit in the generation of the cancellation sound according to the number of occupants on other seats that affect the noise of the specified seat.

Description

Technical Field

[0001] The present invention relates to a noise reduction device, a vehicle, a noise reduction system, and a noise reduction method. Background Art

[0002] As a technology for controlling noise in a vehicle such as an automobile, there is ANC (Active Noise Control) for reducing engine noise and the like of the vehicle. In addition, with the application of the ANC technology, the demand for ACTC (Active Cross Talk Control) for reproducing different contents at each seat in the vehicle is also increasing.

[0003] As a technology related to these, there is known an active noise canceling device that can reduce noise even when the sound field of the set environment changes, in a case where it is impossible to set a wrong microphone at a desired noise control position during use (for example, refer to Patent Document 1).

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2018-072770 Summary of the Invention

[0007] When using an adaptive filter to reduce wideband noise in ANC or ACTC, a feedforward type is generally used. However, since the noise is reduced at the position of the microphone, if the positions of the microphone and the ear are separated, there is a case where the noise is not sufficiently reduced.

[0008] In contrast, in the technology disclosed in Patent Document 1, a pre-made auxiliary filter is used to virtually obtain the sound signal at the position of the ear, thereby achieving noise reduction at the position of the ear.

[0009] In this way, considering the application of a technology that uses a pre-made auxiliary filter to reduce the noise at the position of the ear of the occupant in each seat, a noise reduction system that reproduces respective contents at each seat in the vehicle is realized.

[0010] In addition, in such a noise reduction system, when there is an unoccupied seat in the vehicle, there is a requirement to invalidate the output of the speaker provided in that seat. Thereby, it is possible to expect the effect of reducing the power consumption of the noise reduction device and suppressing noise generation to other seats.

[0011] However, in reality, if the output of the speaker of the unoccupied seat is invalidated, there is a problem that the characteristics of the primary path included in the auxiliary filter change and the noise reduction effect deteriorates.

[0012] One embodiment of the present invention is made in view of the above problems. In a noise reduction system that uses speakers and microphones corresponding to each seat of a vehicle to reduce the noise of each seat, the output of the speaker of the seat without an occupant is made invalid, and the noise reduction effect is improved.

[0013] To solve the above problems, a noise reduction device according to an embodiment of the present invention uses speakers and microphones corresponding to each seat of a vehicle to reduce noise for each seat. The noise reduction device includes: a signal processing unit that generates a cancellation sound for reducing noise at the position of the ears of an occupant on a specified seat using a set auxiliary filter; an operation setting unit that sets the operations of the speaker and microphone corresponding to the seat without an occupant among the seats of the vehicle to be invalid; and an auxiliary filter setting unit that changes the set value of the auxiliary filter used by the signal processing unit in generating the cancellation sound according to the number of occupants on other seats that affect the noise of the specified seat.

[0014] Advantageous Effects of Invention

[0015] According to one embodiment of the present invention, in a noise reduction system that uses speakers and microphones corresponding to each seat of a vehicle to reduce the noise of each seat, it is possible to make the output of the speaker of the seat without an occupant invalid and improve the noise reduction effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 FIG. is an example of the system configuration of a noise reduction system according to one embodiment.

[0017] Figure 2 FIG. is an example of the configuration of a noise reduction device according to one embodiment.

[0018] Figure 3 FIG. is an example of the configuration of a signal processing unit according to one embodiment.

[0019] Figure 4 FIG. is an example of the functional configuration of a control unit according to one embodiment.

[0020] Figure 5 FIG. is a diagram for explaining the outline of the processing of a noise reduction system according to one embodiment.

[0021] Figure 6 FIG. is a flowchart of an example of an operation setting process according to one embodiment.

[0022] Figure 7 FIG. is a flowchart of an example of the setting process of the auxiliary filter in the driver's seat according to one embodiment.

[0023] Figure 8 It is a flowchart showing an example of the setting process of the auxiliary filter in a specified seat representing one embodiment.

[0024] Figure 9 It is a diagram for explaining the effect of the noise reduction method of one embodiment.

[0025] Figure 10 It is a diagram showing a configuration example when outputting a content signal of one embodiment.

[0026] Figure 11 It is a diagram showing a configuration example of the first learning processing unit of one embodiment.

[0027] Figure 12 It is a diagram showing a configuration example of the second learning processing unit of one embodiment.

[0028] Figure 13 It is a diagram showing a virtual sensing image. Detailed Embodiments

[0029] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0030] <System Configuration>

[0031] Figure 1 It is a diagram showing an example of the system configuration of a noise reduction system of one embodiment. The noise reduction system 1 includes, for example, a noise reduction device 100 mounted on a vehicle 10 such as an automobile, and speakers 111L, 111R and microphones 112L, 112R provided corresponding to each seat in the vehicle 10. In addition, the noise reduction system 1 includes a camera 105 or a seat sensor or the like for determining whether there is an occupant on each seat in the vehicle 10.

[0032] In Figure 1 the example, for example, speakers 111L, 111R and microphones 112L, 112R corresponding to the driver's seat 101 are provided on the headrest 110 of the driver's seat 101. In addition, speakers 111L, 111R and microphones 112L, 112R corresponding to each seat are also provided on the headrests 110 of the front passenger seat 102, the rear seats (rear seats) 103 and 104.

[0033] The speakers 111L (first speakers) and microphones 112L (first microphones) corresponding to each seat are arranged near the left ear of the occupant sitting on each seat. In addition, the speakers 111R (second speakers) and microphones 112R (second microphones) corresponding to each seat are arranged near the right ear of the occupant sitting on each seat.

[0034] The noise reduction device 100 is connected to the speakers 111L and 111R and the microphones 112L and 112R of each seat. In each seat, cancellation sounds with the same amplitude and opposite phases are output for the noise, thereby achieving ANC (Active Noise Control) for noise reduction. For example, the noise reduction device 100 generates and outputs a cancellation sound (first cancellation sound) for reducing noise at the position of the left ear of the occupant seated in each seat and a cancellation sound (second cancellation sound) for reducing noise at the position of the right ear of the occupant.

[0035] Preferably, the noise reduction device 100 corresponds to ACTC (Active Cross Talk Control) for reproducing respective contents (for example, music, sounds, ambient sounds, etc.) at each seat in the vehicle 10. Thereby, even when contents such as a movie are reproduced in the rear seats 103 and 104, for example, the influence of the reproduced movie sound can be suppressed, and the driver can enjoy other contents such as music at the driver's seat 101.

[0036] (Regarding virtual sensing)

[0037] A normal ANC system is, for example, as Figure 13 shown in (A) of, obtains noise 1302 output from the noise source 1301 through the microphone 1305, and generates a cancellation sound 1304 for canceling the noise. In addition, the ANC system cancels the noise at the location of the microphone 1305 by outputting the generated cancellation sound 1304 from the speaker 1303. Therefore, for example, as Figure 13 shown in (A) of, when the distance d between the microphone 1305 and the ear 1306 is far, the noise may not be sufficiently reduced.

[0038] Therefore, in the present embodiment, for example, a technique such as the following virtual sensing is utilized: an auxiliary filter that has been pre-learned using a virtual head is used. For example, as Figure 13 shown in (B) of, signal processing is performed such that the virtual microphone 1311 is located at the position of the ear 1306. Thereby, the noise reduction device 100 can generate, for example, a cancellation sound 1312 for canceling the noise at the position of the occupant's ear using a pre-made auxiliary filter. In addition, the noise reduction device 100 can cancel the noise near the location of the virtual microphone 1311, that is, near the ear 1306, by outputting the generated cancellation sound 1312 from the speaker 1303.

[0039] (Outline of processing)

[0040] In the present embodiment, the same noise reduction process is performed for each seat. Here, as an example, the process for reducing the noise of the driver's seat 101 will be mainly described. Additionally, here, it is mainly assumed that the sounds (contents) output from the speakers 111L and 111R of the rear seats 103 and 104 are noise sources that affect the noise of the driver's seat 101, and the following description will be made based on this assumption.

[0041] On the other hand, the speakers 111L and 111R of the passenger seat 102 have directivity in the front, for example, and hardly radiate sound to the side. Therefore, the influence of the sounds output from the speakers 111L and 111R of the passenger seat 102 on the noise of the driver's seat 101 can be ignored (or the influence is small).

[0042] The noise reduction device 100 of the present embodiment has, for example, the following function: based on the image obtained by photographing the interior of the vehicle 10 using the camera 105, it determines whether there is an occupant in each seat, and sets the operations of the speakers and microphones corresponding to the seats without occupants to be invalid.

[0043] For example, when there is no occupant in the rear seat 104, the noise reduction device 100 sets the speakers 111L and 111R and the microphones 112L and 112R corresponding to the rear seat 104 to be invalid (for example, mute on), and aborts the noise reduction process for the rear seat 104. On the other hand, when there is an occupant in the rear seat 104, the noise reduction device 100 sets the speakers 111L and 111R and the microphones 112L and 112R corresponding to the rear seat 104 to be valid (for example, mute off), and performs the noise reduction process for the rear seat 104.

[0044] Thereby, the noise reduction device 100 can reduce the power consumption required for the noise reduction process of the seat without an occupant (for example, the rear seat 104), and can abort the output of the content that would be a noise source for other seats (for example, the driver's seat 101).

[0045] However, in reality, for example, if the output of the speakers of the rear seat 104 without an occupant is made invalid, the characteristics of the primary path included in the secondary filter will change, and for example, the noise reduction effect of the driver's seat 101 will deteriorate.

[0046] Therefore, the noise reduction device 100 has the following function: based on the number of occupants on the rear seats 103 and 104, which are other seats that affect the noise of the driver's seat 101, it changes the function of the secondary filter used in the generation of the cancellation sound for reducing the noise of the driver's seat 101.

[0047] For example, the noise reduction device 100 performs a learning process in a state where the speakers 111L, 111R and microphones 112L, 112R corresponding to the rear seats 103, 104 that affect the noise of the driver's seat 101 are set to be valid, and stores in advance the obtained auxiliary filter (auxiliary filter A).

[0048] In addition, the noise reduction device 100 performs a learning process in a state where the speakers and microphones corresponding to one of the seats (for example, the rear seat 104) among the rear seats 103, 104 that affect the noise of the driver's seat 101 are set to be invalid, and stores in advance the obtained auxiliary filter (auxiliary filter B).

[0049] And, when there are passengers on the rear seats 103, 104 that affect the noise of the driver's seat 101, the noise reduction device 100 applies the pre-stored auxiliary filter A to generate a cancellation sound for reducing the noise of the driver's seat 101.

[0050] On the other hand, when there is no passenger in one of the rear seats 103, 104 that affect the noise of the driver's seat 101, the noise reduction device 100 applies the pre-stored auxiliary filter B to generate a cancellation sound for reducing the noise of the driver's seat 101.

[0051] In addition, when there are no passengers on both of the rear seats 103, 104 that affect the noise of the driver's seat 101, there is no noise source that affects the noise of the driver's seat 101. Therefore, the noise reduction device 100 can also stop the noise reduction process of the driver's seat 101, for example.

[0052] In addition, if only the outputs of the speakers 111L, 111R are invalidated for the seat without a passenger, the adaptation of the adaptive filter in the seat without a passenger will progress, and when the output of the speaker becomes valid again, sometimes a large noise (pop sound) will be generated.

[0053] Therefore, in the noise reduction device 100 of the present embodiment, for the seat without a passenger, in addition to the outputs of the speakers 111L, 111R, the inputs of the microphones 112L, 112R are also invalidated, and control is performed in a manner that avoids inappropriate adaptation.

[0054] In addition, in the above description, the case of reducing the noise for the driver's seat 101 has been described, but the noise reduction device 100 can perform the same process for each seat of the vehicle 10.

[0055] For example, when the noise reduction device 100 reduces the noise of the front passenger seat 102, the sounds (contents) output from the speakers 111L and 111R of the rear seats 103 and 104 become noise sources that affect the noise of the front passenger seat 102. Therefore, the noise reduction device 100 can change the auxiliary filter used in generating the cancellation sound for reducing the noise of the front passenger seat 102 according to the number of occupants on the other seats, namely the rear seats 103 and 104, that affect the noise of the front passenger seat 102.

[0056] In addition, when the noise reduction device 100 reduces the noise of the rear seat (for example, the rear seat 103), the sounds (contents) output from the speakers 111L and 111R of the driver's seat 101 and the front passenger seat 102 become noise sources that affect the noise of the rear seat. Therefore, the noise reduction device 100 can change the auxiliary filter used in generating the cancellation sound for reducing the noise of the rear seat according to the number of occupants on the other seats, namely the driver's seat 101 and the front passenger seat 102, that affect the noise of the rear seat.

[0057] In addition, Figure 1 The system configuration of the noise reduction system 1 shown is an example. For example, the speakers 111L and 111R, or the microphones 112L and 112R corresponding to each seat in the vehicle 10 may also be provided outside the headrest 110. In addition, the noise reduction device 100 is not limited to the images captured by the camera 105. For example, it can also determine whether there are occupants in each seat based on the information obtained from the in-vehicle ECU (Electronic Control Unit) mounted on the vehicle 10 and the signals output from seat sensors and the like.

[0058] <Example of the configuration of the noise reduction device>

[0059] Figure 2 is a diagram showing an example of the configuration of the noise reduction device according to an embodiment. In addition, in Figure 2 for the sake of easy explanation, only the configuration used by the noise reduction device 100 to reduce the noise of each seat in the vehicle 10 is described. Regarding the configuration when the noise reduction device 100 outputs contents such as music and sounds, it will be described later using Figure 11 described later.

[0060] The noise reduction device 100 includes signal processing units 210-1 to 210-4 corresponding to each seat in the vehicle 10 and a control unit 220. For example, the signal processing unit 210-1 performs Figure 1 the noise reduction process for the driver's seat 101, and the signal processing unit 210-2 performs the noise reduction process for the front passenger seat 102. In addition, the signal processing unit 210-2, for example, performs Figure 1For the noise reduction process of the rear seat 103, the signal processing unit 210-4 performs the noise reduction process of the rear seat 104.

[0061] Since the configurations of the signal processing units 210-1 to 210-4 are common, a signal processing unit 210 (for example, the signal processing unit 210-1) will be described here. In addition, in the following description, when referring to any of the signal processing units 210-1 to 210-4, "signal processing unit 210" is used.

[0062] In addition, in Figure 2 it is assumed that the signal processing units 210-2 to 210-4 are respectively connected with noise sources, speakers, and microphones corresponding to each signal processing unit 210 in the same manner as the signal processing unit 210-1.

[0063] The signal processing units 210-1 to 210-4 are implemented, for example, by the DSP (Digital Signal Processor) included in the noise reduction device 100, and perform the noise reduction process for each seat in the vehicle 10 according to the control from the control unit 220.

[0064] A noise signal x1(n) generated by the first noise source 201 and a noise signal x2(n) generated by the second noise source 202 are input to the signal processing unit 210. The noise signal x1(n) and the noise signal x2(n) correspond to the reference signals of ANC.

[0065] For example, in the signal processing unit 210-1 that performs the noise reduction process for the driver's seat 101, as the noise signal x1(n), the content signal such as music output from the rear seat 103 is input, and as the noise signal x2(n), the content signal output from the rear seat 104 is input.

[0066] An error signal err p1 (n) output from the microphone 112L and an error signal err p2 (n) output from the microphone 112R are input to the signal processing unit 210.

[0067] The signal processing unit 210 uses the noise signal x1(n), the noise signal x2(n), the error signal err p1 (n), and the error signal err p2 (n) to generate a cancellation signal CA1(n) for canceling noise at the first cancellation point. In addition, the signal processing unit 210 reduces the noise at the first cancellation point (for example, the left ear of the occupant) by outputting the generated cancellation signal CA1(n) from the speaker 111L.

[0068] Similarly, the signal processing unit 210 uses the noise signal x1(n), the noise signal x2(n), the error signal err p1 (n), and the error signal err p2 (n) to generate a cancellation signal CA2(n) for canceling noise at the second cancellation point. In addition, the signal processing unit 210 reduces the noise at the second cancellation point (e.g., the right ear of the occupant) by outputting the generated cancellation signal CA2(n) from the speaker 111R. Additionally, regarding a specific configuration example of the signal processing unit, it will be described later Figure 3 .

[0069] The control unit 220 is a computer that controls the entire noise reduction device 100, and is composed of, for example, a CPU (Central Processing Unit), a memory, a storage device, and a communication I / F (Interface), etc. The control unit 220 realizes the functional configuration described later Figure 4 by executing a prescribed program.

[0070] (Configuration example of the signal processing unit)

[0071] Figure 3 is a diagram showing a configuration example of the signal processing unit according to an embodiment. The signal processing unit 210 includes a first system that mainly performs processing related to the first cancellation point and a second system that mainly performs processing related to the second cancellation point.

[0072] As Figure 3 shown, the signal processing unit 210 includes: a first auxiliary filter 1111 of the first system that sets the transfer function H 11 (z), a first auxiliary filter 1112 of the second system that sets the transfer function H 12 (z), a first variable filter 1113 of the first system, a first adaptive algorithm execution unit 1114 of the first system, a first variable filter 1115 of the second system, a first adaptive algorithm execution unit 1116 of the second system, an adder 1117 for error correction of the first system, and an adder 1118 for generating cancellation sound of the first system.

[0073] The first variable filter 1113 of the first system and the first adaptive algorithm execution unit 1114 of the first system constitute an adaptive filter, and the first adaptive algorithm execution unit 1114 of the first system updates the transfer function W 11(z). Additionally, the first variable filter 1115 of the second system and the first adaptive algorithm execution unit 1116 of the second system form an adaptive filter, and the first adaptive algorithm execution unit 1116 of the second system updates the transfer function W of the first variable filter 1115 of the second system through the MEFX LMS algorithm 12 (z).

[0074] Additionally, the signal processing unit 210 includes a second auxiliary filter 1121 of the first system with a preset transfer function H 21 (z), a second auxiliary filter 1122 of the second system with a preset transfer function H 22 (z), a second variable filter 1123 of the first system, a second adaptive algorithm execution unit 1124 of the first system, a second variable filter 1125 of the second system, a second adaptive algorithm execution unit 1126 of the second system, an error correction adder 1127 of the second system, and a cancellation sound generation adder 1128 of the second system.

[0075] Moreover, the second variable filter 1123 of the first system and the second adaptive algorithm execution unit 1124 of the first system form an adaptive filter, and the second adaptive algorithm execution unit 1124 of the first system updates the transfer function W of the second variable filter 1123 of the first system through the MEFX LMS algorithm 21 (z).

[0076] Additionally, the second variable filter 1125 of the second system and the second adaptive algorithm execution unit 1126 of the second system form an adaptive filter, and the second adaptive algorithm execution unit 1126 of the second system updates the transfer function W of the second variable filter 1125 of the second system using the MEFX LMS algorithm 22 (z).

[0077] In such a configuration, the noise signal x1(n) input to the signal processing unit 210 is sent to the first auxiliary filter 1111 of the first system, the first auxiliary filter 1112 of the second system, the first variable filter 1113 of the first system, and the first variable filter 1115 of the second system.

[0078] The error signal err p1 (n) input from the microphone 112L is sent to the error correction adder 1117 of the first system, and the error signal err p2 (n) input from the microphone 112R is sent to the error correction adder 1127 of the second system.

[0079] Also, the output of the first auxiliary filter 1111 of the first system is sent to the adder 1117 for error correction of the first system, and the output of the first auxiliary filter 1112 of the second system is sent to the adder 1127 for error correction of the second system. Additionally, the output of the first variable filter 1113 of the first system is sent to the adder 1118 for generating cancellation sound of the first system, and the output of the first variable filter 1115 of the second system is sent to the adder 1128 for generating cancellation sound of the second system.

[0080] Furthermore, the noise signal x2(n) input to the signal processing unit 210 is sent to the second auxiliary filter 1121 of the first system, the second auxiliary filter 1122 of the second system, the second variable filter 1123 of the first system, and the second variable filter 1125 of the second system.

[0081] Also, the output of the second auxiliary filter 1121 of the first system is sent to the adder 1117 for error correction of the first system, and the output of the second auxiliary filter 1122 of the second system is sent to the adder 1127 for error correction of the second system. In addition, the output of the second variable filter 1123 of the first system is sent to the adder 1118 for generating cancellation sound of the first system, and the output of the second variable filter 1125 of the second system is sent to the adder 1128 for generating cancellation sound of the second system.

[0082] The adder 1117 for error correction of the first system adds the output of the first auxiliary filter 1111 of the first system, the output of the second auxiliary filter 1121 of the first system, and the error signal err p1 (n) to generate the error signal err h1 (n). Also, the adder 1127 for error correction of the second system adds the output of the first auxiliary filter 1112 of the second system, the output of the second auxiliary filter 1122 of the second system, and the error signal err p2 (n) to generate the error signal err h2 (n).

[0083] Then, the error signal err h1 (n) and the error signal err h2 (n) are output as multiple errors to the first adaptive algorithm execution unit 1114 of the first system, the first adaptive algorithm execution unit 1116 of the second system, the second adaptive algorithm execution unit 1124 of the first system, and the second adaptive algorithm execution unit 1126 of the second system.

[0084] In addition, the adder 1118 for generating cancellation sound in the first system adds the output of the first variable filter 1113 in the first system to the output of the second variable filter 1123 in the first system, generates the first cancellation signal CA1(n), and outputs it from the speaker 111L. In addition, the adder 1128 for generating cancellation sound in the second system adds the output of the first variable filter 1115 in the second system to the output of the second variable filter 1125 in the second system, generates the second cancellation signal CA2(n), and outputs it from the speaker 111R.

[0085] Then, the first adaptive algorithm execution unit 1114 in the first system updates the transfer function W 11 (z) of the first variable filter 1113 in the first system by using the MEFX LMS algorithm, so that the error signals err h1 (n) and err h2 (n) input as multiple errors become 0. In addition, the first adaptive algorithm execution unit 1116 in the second system updates the transfer function W12(z) of the first variable filter 1115 in the second system by the MEFX LMS algorithm, so that the error signals err h1 (n) and err h2 (n) input as multiple errors become 0.

[0086] In addition, the second adaptive algorithm execution unit 1124 in the first system updates the transfer function W 21 (z) of the second variable filter 1123 in the first system by the MEFX LMS algorithm, so that the error signals err h1 (n) and err h2 (n) input as multiple errors become 0. Furthermore, the second adaptive algorithm execution unit 1126 in the second system updates the transfer function W 22 (z) of the second variable filter 1125 in the second system by using the MEFX LMS algorithm, so that the error signals err h1 (n) and err h2 (n) input as multiple errors become 0.

[0087] In addition, the transfer functions H 11 (z) of the first auxiliary filter 1111 in the first system of the signal processing unit 210, the transfer functions H 12 (z) of the first auxiliary filter 1112 in the second system, and the transfer functions H 22 (z) of the second auxiliary filter 1121 in the first system can be determined by the learning process described later.

[0088] In addition, in the present embodiment, the combination of the first auxiliary filter 1111 of the first system, the first auxiliary filter 1112 of the second system, the second auxiliary filter 1121 of the first system, and the second auxiliary filter 1122 of the second system is referred to as the "auxiliary filter". In addition, the transfer functions H 11 (z), H 12 (z), H 21 (z), and H 22 (z) of the auxiliary filter are referred to as the "set values of the auxiliary filter".

[0089] (Functional configuration of the control unit)

[0090] Figure 4 FIG. is an example showing the functional configuration of the control unit in one embodiment. The control unit 200 realizes, for example, an occupant determination unit 501, an operation setting unit 502, an auxiliary filter setting unit 503, a storage unit 504, a learning control unit 505, etc. by executing a predetermined program by the CPU included in the control unit 200. In addition, at least a part of the above-described functional configurations may be implemented by hardware.

[0091] The occupant determination unit 501 determines the presence or absence of an occupant in each seat in the vehicle 10. For example, the occupant determination unit 501 analyzes an image obtained by photographing the inside of the vehicle 10 by the camera 105, and determines whether there is an occupant in each of the driver's seat 101, the front passenger seat 102, the rear seat 103, and the rear seat 104.

[0092] However, it is not limited thereto. The occupant determination unit 501 may also acquire an output signal from a seat sensor or the like provided in the vehicle 10 to determine the presence or absence of an occupant in each seat in the vehicle 10. Alternatively, the occupant determination unit 501 may determine the presence or absence of an occupant in each seat in the vehicle 10 based on information obtained from an in-vehicle ECU or the like mounted on the vehicle 10.

[0093] The operation setting unit 502 controls the signal processing units 210-1 to 210-4, and sets the speakers 111L, 111R and the microphones 112L, 112R corresponding to the seats determined by the occupant determination unit 501 as having no occupant to be invalid (for example, mute on). In addition, the operation setting unit 502 controls the signal processing units 210-1 to 210-4, and sets the speakers 111L, 111R and the microphones 112L, 112R corresponding to the seats determined by the occupant determination unit 501 as having an occupant to be valid (for example, mute off, etc.).

[0094] For example, as shown in (A) of Figure 5 , when there are occupants in each seat in the vehicle 10, the operation setting unit 502 maintains the settings of the speakers and microphones corresponding to each seat in an effective state. In addition, for example, asFigure 5 As shown in (B), when the occupant in the rear seat 104 gets off, the operation setting unit 502 sets the speaker and microphone corresponding to the rear seat 104 to invalid.

[0095] In addition, the operation setting unit 502, for example, as Figure 5 shown in (B), when an occupant sits on the rear seat 104 where there was no occupant before, the operation of the speaker corresponding to the rear seat 104 on which the occupant sits is set to valid. Further, the operation setting unit 502 sets the settings of the speaker and microphone to valid in the order of the speaker and microphone corresponding to the rear seat 104. Alternatively, the operation setting unit 502 may also make the settings of the speaker and microphone corresponding to the rear seat 104 valid simultaneously.

[0096] In this way, by controlling during the period when the operation of the speaker is invalid so that the operation of the microphone does not become valid, it is possible to perform the adaptation of the adaptive filter in an abnormal state and suppress the output of unpleasant noise and noise.

[0097] In addition, the operation setting unit 502 may also set the speaker and microphone corresponding to the seat determined by the occupant determination unit 501 as having no occupant to invalid, and cause the signal processing unit 210 to shift to a power-saving state or the like. Thereby, it is possible to expect a reduction effect on the power consumption of the noise reduction device 100, and it is possible to suppress the adaptation of the adaptive filter in an abnormal state.

[0098] The auxiliary filter setting unit 503 sets the setting values of the auxiliary filters of the signal processing units 210-1 to 210-4. Here, as described above, the auxiliary filter corresponds to Figure 3 the combination of the first auxiliary filter 1111 of the first system, the first auxiliary filter 1112 of the second system, the second auxiliary filter 1121 of the first system, and the second auxiliary filter 1122 of the second system. In addition, as described above, the setting value of the auxiliary filter corresponds to the transfer function H 11 (z), H 12 (z), H 21 (z), and H 22 (z).

[0099] The auxiliary filter setting unit 503 of the present embodiment has the following function: changing the setting value of the auxiliary filter used in the generation of the cancellation sound by the signal processing unit 210 corresponding to a specified seat according to the number of occupants on other seats that affect the noise of the specified seat.

[0100] For example, the auxiliary filter setting unit 503 performs the learning process described later in a state where the speakers and microphones corresponding to the rear seats 103 and 104 that affect the noise in the driver's seat 101 are set to be valid, and pre-stores the set values of the obtained auxiliary filter (hereinafter referred to as auxiliary filter A).

[0101] In addition, the auxiliary filter setting unit 503 performs the learning process in a state where the speakers and microphones corresponding to one of the rear seats 103 and 104 (for example, the rear seat 104) are set to be invalid, and pre-stores the set values of the obtained auxiliary filter (hereinafter referred to as auxiliary filter B).

[0102] And, for example, when there are occupants on the rear seats 103 and 104 that affect the noise in the driver's seat 101 as shown in (A) of Figure 5 the auxiliary filter setting unit 503 sets the set values of the pre-stored auxiliary filter A to the auxiliary filter of the signal processing unit 210-1.

[0103] On the other hand, for example, when there is no occupant in one of the rear seats 103 and 104 that affect the noise in the driver's seat 101 as shown in (B) of Figure 5 the auxiliary filter setting unit 503 sets the set values of the pre-stored auxiliary filter B to the auxiliary filter of the signal processing unit 210-1.

[0104] In addition, the driver's seat 101 is an example of a specified seat. For example, when the specified seat is the rear seat 103 or the rear seat 104, the seats that affect the noise of the specified seat become the driver's seat 101 and the front passenger seat. Also, for example, when the specified seat is the front passenger seat 102, the seats that affect the noise of the specified seat become the rear seats 103 and 104.

[0105] The storage unit 504 stores various information including the set values of the auxiliary filter A obtained in advance through learning processes and the set values of the auxiliary filter B, etc., for example.

[0106] The learning control unit 505 controls the learning process in order to obtain the set values of the auxiliary filter A and the set values of the auxiliary filter B. The learning process will be described later.

[0107] In addition, the set values of the auxiliary filter A and the set values of the auxiliary filter B can be, for example, the set values obtained by pre-performing the learning process in other vehicles having the same configuration as the noise reduction system 1. Therefore, the noise reduction device 100 may not have to have the learning control unit 505.

[0108] <Flow of the process>

[0109] Next, the processing flow of the noise reduction method according to the present embodiment will be described.

[0110] (Action setting process)

[0111] Figure 6 2 is a flowchart showing an example of an operation setting process according to one embodiment. This process shows an example of an operation setting process executed by the noise reduction system 1 .

[0112] In step S601, the occupant determination unit 501 of the control unit 220 determines whether there are occupants in each seat in the vehicle 10. For example, the occupant determination unit 501 analyzes the image captured by the camera 105 of the vehicle 10 to determine whether there are occupants in each seat. Alternatively, the occupant determination unit 501 determines whether there are occupants in each seat based on the output signal of the seat sensor provided in the vehicle 10, the information obtained from the vehicle-mounted ECU, and the like.

[0113] In step S602 , the operation setting unit 502 of the control unit 220 sets the operation of the speakers 111L, 111R and the microphones 112L, 112R of the seats where passengers are located in the vehicle 10 to be enabled.

[0114] For example, when the signal processing unit 210 corresponding to the seat with passengers mutes the speaker output and the microphone input, the action setting unit 502 instructs the signal processing unit 210 to release the muting in the order of the speaker output and the microphone input. In addition, when the signal processing unit 210 corresponding to the seat with passengers is set to the power saving state, the action setting unit 502 instructs the signal processing unit 210 to return to the normal state.

[0115] Furthermore, when the operation of the speaker and the microphone of a seat where an occupant is present has been set to be effective, the operation setting unit 502 may maintain the state in which the operation of the speaker and the microphone of the seat is set to be effective.

[0116] In step S603 , the operation setting unit 502 of the control unit 220 sets the operation of the speakers 111L, 111R and the microphones 112L, 112R of the seats without passengers in the vehicle 10 to be invalid.

[0117] For example, when the signal processing unit 210 corresponding to the seat without an occupant has not muted the speaker output and the microphone input, the action setting unit 502 instructs the signal processing unit 210 to mute the speaker output and the microphone input. Alternatively, the action setting unit 502 may stop the processing of the signal processing unit 210 corresponding to the seat without an occupant and set the signal processing unit 210 to a power saving state.

[0118] The noise reduction system 1 can, for example, stop the noise reduction process in the unoccupied seats in the vehicle 10 and the output of content such as music and sound by repeatedly performing the above-described process.

[0119] (Auxiliary filter setting process for the driver's seat)

[0120] Figure 7 is a flowchart showing an example of the setting process of the auxiliary filter in the driver's seat in one embodiment. This process represents an example of the auxiliary filter setting process that the control unit 220 of the noise reduction device 100 performs on the signal processing unit 210-1 corresponding to the driver's seat 101, for example. This process is, for example, parallel to the Figure 6 action setting process shown, or is executed before the Figure 6 action setting process shown.

[0121] In step S701, the occupant determination unit 501 of the control unit 220 determines the presence or absence of an occupant in each seat in the vehicle 10. In addition, this process can be common to the Figure 6 process of step S601.

[0122] In step S702, the auxiliary filter setting unit 503 of the control unit 220 branches the process according to whether there are two occupants in the rear seats 103 and 104 that affect the noise of the driver's seat 101 (whether there is someone in each of the rear seats 103 and 104).

[0123] When there are two occupants in the rear seats 103 and 104, the auxiliary filter setting unit 503 transfers the process to step S703. On the other hand, when there are not two occupants in the rear seats 103 and 104, the auxiliary filter setting unit 503 transfers the process to step S704.

[0124] When transferring to step S703, the auxiliary filter setting unit 503 sets the set value of the pre-stored auxiliary filter A for the auxiliary filter used in the generation of the cancellation sound in the signal processing unit 210-1 corresponding to the driver's seat 101. For example, the auxiliary filter setting unit 503 sets the auxiliary filter of the signal processing unit 210-1 to the transfer functions H 11 (z), H 12 (z), H 21 (z), and H 22 (z) learned in the state where the speakers and microphones of the rear seats 103 and 104 are set to be valid. In addition, when the set value of the auxiliary filter A has already been set in the signal processing unit 210-1, the auxiliary filter setting unit 503 only needs to maintain the current set value.

[0125] When transferring to step S704, the auxiliary filter setting unit 503 branches the process according to whether there is one occupant or no occupant in the rear seats 103 and 104.

[0126] When there is one occupant in the rear seats 103 and 104, the auxiliary filter setting unit 503 transfers the process to step S705. On the other hand, when there is no occupant in the rear seats 103 and 104, the auxiliary filter setting unit 503 ends Figure 7 the process.

[0127] When transferring to step S705, the auxiliary filter setting unit 503 sets the set value of the pre-stored auxiliary filter B for the auxiliary filter used in the generation of the cancellation sound by the signal processing unit 210-1 corresponding to the driver's seat 101. For example, the auxiliary filter setting unit 503 sets the auxiliary filter of the signal processing unit 210-1 to the transfer function H 11 (z), H 12 (z), H 21 (z) and H 22 (z) of the auxiliary filter B learned in the state where the speakers and microphones on one side of the rear seats 103 and 104 are set to be invalid. In addition, when the set value of the auxiliary filter B has already been set in the signal processing unit 210-1, the auxiliary filter setting unit 503 only needs to maintain the current set value.

[0128] Through the above-mentioned various processes, for example, when there is no occupant in the rear seat 104 of the vehicle 10, the operations of the speaker and microphone of the rear seat 104 are set to be invalid, and the cancellation sound of the driver's seat 101 is generated using the auxiliary filter learned in the state where there is one occupant in the rear seat.

[0129] (Auxiliary filter setting process for a specified seat)

[0130] In addition, Figure 7 the setting process of the auxiliary filter as shown can also be executed for each seat (specified seat) in the vehicle 10.

[0131] Figure 8 is a flowchart showing an example of the auxiliary filter setting process in the driver's seat of one embodiment. This process shows the flowchart when the setting process of the auxiliary filter described in Figure 7 is applied to a specified seat in the vehicle 10. In addition, since the basic processing content is the same as the auxiliary filter setting process shown in Figure 7 , the detailed description of the same processing content is omitted here.

[0132] In step S801, the occupant determination unit 501 of the control unit 220 determines whether there is an occupant in each seat in the vehicle 10. In addition, this process is the same asFigure 6 Step S601 and Figure 7 Step S701 are processed in the same way.

[0133] In step S802, the auxiliary filter setting unit 503 of the control unit 220 branches the processing according to whether there is an occupant in each of the other seats that affect the noise of the specified seat.

[0134] For example, when the specified seat is the co-pilot seat 102 (or the driver's seat 101), the other seats that affect the specified seat become the rear seats 103 and 104. In addition, when the specified seat is the rear seat 103 or the rear seat 104, the other seats that affect the noise of the specified seat become the driver's seat 101 and the co-pilot seat 102.

[0135] When there is an occupant in each of the other seats that affect the noise of the specified seat, the auxiliary filter setting unit 503 transfers the processing to step S803. On the other hand, when there is no occupant in each of the other seats that affect the noise of the specified seat (when either one or both of the other seats have no occupants), the auxiliary filter setting unit 503 transfers the processing to step S804.

[0136] When transferring to step S803, the auxiliary filter setting unit 503 sets the set value of the pre-stored auxiliary filter A for the auxiliary filter used by the signal processing unit 210 corresponding to the specified seat in the generation of the cancellation sound.

[0137] For example, when the specified seat is the rear seat 103, the auxiliary filter setting unit 503 sets the set value of the auxiliary filter A learned in the state where the speakers and microphones corresponding to the driver's seat 101 and the co-pilot seat 102 are set to be effective for the signal processing unit 210-3. Similarly, when the specified seat is the rear seat 104, the auxiliary filter setting unit 503 sets the set value of the auxiliary filter A learned in the state where the speakers and microphones corresponding to the driver's seat 101 and the co-pilot seat 102 are set to be effective for the signal processing unit 210-4.

[0138] In addition, when the specified seat is the co-pilot seat 102, the auxiliary filter setting unit 503 sets the set value of the auxiliary filter A learned in the state where the speakers and microphones corresponding to the rear seats 103 and 104 are set to be effective for the signal processing unit 210-2. In addition, the processing when the specified seat is the driver's seat 101 is the same as that of Figure 7 Step S703.

[0139] When transferring to step S804, the auxiliary filter setting unit 503 branches the process according to whether there is an occupant or not on a part of other seats that affect the noise of a specified seat.

[0140] When there is an occupant on a part of other seats that affect the noise of a specified seat, the auxiliary filter setting unit 503 transfers the process to step S805. On the other hand, when there is no occupant on other seats that affect the noise of a specified seat, the auxiliary filter setting unit 503 ends Figure 8 the process.

[0141] When transferring to step S805, the auxiliary filter setting unit 503 sets the set value of the pre-stored auxiliary filter B for the auxiliary filter used in the generation of the cancellation sound by the signal processing unit 210 corresponding to the specified seat.

[0142] For example, when the specified seat is the rear seat 103, the auxiliary filter setting unit 503 sets the set value of the auxiliary filter B learned in a state where the speaker and microphone corresponding to either the driver's seat 101 or the front passenger seat 102 are set to invalid for the signal processing unit 210-3. Similarly, when the specified seat is the rear seat 104, the auxiliary filter setting unit 503 sets the set value of the auxiliary filter B learned in a state where the speaker and microphone corresponding to either the driver's seat 101 or the front passenger seat 102 are set to invalid for the signal processing unit 210-4.

[0143] In addition, when the specified seat is the front passenger seat 102, the auxiliary filter setting unit 503 sets the set value of the auxiliary filter B learned in a state where the speaker and microphone corresponding to either of the rear seats 103 and 104 are set to invalid for the signal processing unit 210-2. In addition, the process when the specified seat is the driver's seat 101 is the same as Figure 7 that of step S705.

[0144] Through the above processing, the control unit 220 can appropriately change the setting of the auxiliary filter used in the generation of the cancellation sound by the signal processing unit 210 corresponding to each seat according to the number of occupants on other seats that affect each seat in the vehicle 10.

[0145] <Effect>

[0146] Figure 9 is a diagram for explaining the effect of the noise reduction method of one embodiment. Figure 9 is a graph showing the noise reduction effect of the noise reduction system 1, with the horizontal axis representing frequency and the vertical axis representing the sound pressure of the noise.

[0147] InFigure 9 In this case, line 901 represents the sound pressure of the reference signal as a noise source. Additionally, line 902 represents the sound pressure of the noise measured at the driver's seat 101 in a state where the speakers of the rear seats 103 and 104 are set to be effective and the noise reduction process is set to be ineffective.

[0148] On the other hand, Figure 9 Line 903 represents the sound pressure of the noise measured at the driver's seat 101 in a state where the speaker of the rear seat 103 is set to be effective, the speaker of the rear seat 104 is set to be ineffective, and the noise reduction process is set to be ineffective. Thus, even when the noise reduction process based on the noise reduction device 100 is set to be ineffective, if the speaker of the rear seat 104 is set to be ineffective, the noise sources affecting the driver's seat 101 are reduced, and therefore the sound pressure of the noise at the driver's seat 101 can be reduced.

[0149] Additionally, Figure 9 Line 904 represents the sound pressure of the noise measured at the driver's seat 101 in a state where the speakers of the rear seats 103 and 104 are set to be effective and the noise reduction process applied with the auxiliary filter A is set to be effective. Thus, through the noise reduction process based on the noise reduction device 100, the sound pressure of the noise at the driver's seat 101 can be significantly reduced.

[0150] On the other hand, Figure 9 Line 905 represents the sound pressure of the noise measured at the driver's seat 101 in a state where the speaker of the rear seat 103 is set to be effective, the speaker of the rear seat 104 is set to be ineffective, and the noise reduction process applied with the auxiliary filter A (2-seat filter) is set to be effective. Thus, when performing the noise reduction process by applying the auxiliary filter A, if the speaker of one of the rear seats 103 and 104 that is a noise source is set to be ineffective, it can be seen that the noise reduction effect at the driver's seat 101 deteriorates. It is generally considered that this is because, for example, if the output of the speaker in one of the rear seats 103 and 104 is made ineffective, the characteristics of the primary path included in the auxiliary filter change.

[0151] Therefore, when the noise reduction device 100 of the present embodiment makes the output of the speaker in one of the rear seats 103 and 104 ineffective, it applies the auxiliary filter B (1-seat filter). Figure 9The line 906 indicates the sound pressure of the noise measured at the driver's seat 101 in a state where the speaker of the rear seat 103 is set to be effective, the speaker of the rear seat 104 is set to be ineffective, and the noise reduction process applying the auxiliary filter B is set to be effective. In this way, when the output of the speaker in one of the rear seats 103 and 104 is set to be ineffective, by applying the auxiliary filter B to perform the noise reduction process, the noise reduction effect at the driver's seat 101 can be significantly improved.

[0152] In addition, thereby, it is also possible to save the power consumption used for the noise reduction process corresponding to the seat without an occupant.

[0153] <Configuration example when outputting content signal>

[0154] Figure 10 It is a diagram showing a configuration example when outputting a content signal of one embodiment.

[0155] For example, in Figure 2 the noise reduction device 100 shown, when outputting content such as music, sound, and ambient sound from the speakers 111L and 111R, as Figure 10 shown, it is only necessary to add a volume adjustment unit 1001, a sound quality adjustment unit 1002, a synthesis unit 1003, etc. to each signal processing unit 210.

[0156] The volume adjustment unit 1001 is realized, for example, by implementing the DSP of the signal processing unit 210 or a volume adjustment circuit, etc., and changes the volume of the content signal (L, R) such as music output from the speakers 111L and 111R according to the user's operation, etc.

[0157] The sound quality adjustment unit 1002 is realized, for example, by implementing the DSP of the signal processing unit 210 or a sound quality adjustment circuit, etc., and changes the frequency characteristics, delay time, gain, etc. of the content signal (L, R) according to the user's operation, etc.

[0158] The synthesis unit 1003 is realized, for example, by implementing the DSP of the signal processing unit 210 or a sound synthesis circuit, etc., synthesizes the content signal (L) and the cancellation signal CA1(n), and outputs the result to the speaker 111L. In addition, the synthesis unit 1003 synthesizes the content signal (R) and the cancellation signal CA2(n), and outputs the result to the speaker 111R.

[0159] According to the above configuration, for example, the signal processing unit 210-1 corresponding to the driver's seat 101 can output content to the driver's seat 101 with the volume and sound quality preferred by the user, and reduce the noise from the rear seats 103 and 104.

[0160] <Learning process>

[0161] Next, the setting values for obtaining the auxiliary filter settings for the signal processing unit 210, that is, the transfer functions H 11 (z), H 12 (z), H 21 (z), H 22 (z) will be described for the learning process.

[0162] The learning process is performed in a standard acoustic environment where the noise reduction system 1 is applied, that is, in a standard acoustic environment (for example, inside the vehicle 10, etc.). In addition, the learning process includes a first-stage learning process and a second-stage learning process.

[0163] Figure 11 is a diagram showing a configuration example of the first learning processing unit of an embodiment. As Figure 11 shown, the first-stage learning process is performed in a configuration where the signal processing unit 210 of the noise reduction device 100 is replaced with the first learning processing unit 1100. Here, as Figure 11 shown, the first learning processing unit 1100 includes removing the first auxiliary filter 1111 of the first system, the first auxiliary filter 1112 of the second system, the second auxiliary filter 1121 of the first system, the second auxiliary filter 1122 of the second system, the first error correction adder 1117 of the first system, and the second error correction adder 1127 of the second system from the Figure 3 shown signal processing unit 210.

[0164] In addition, the first-stage learning process is performed by connecting the virtual microphone 1102L disposed at the first cancellation point and the virtual microphone 1102R disposed at the second cancellation point to the first learning processing unit 1100.

[0165] In addition, in the first learning processing unit 1100, it is configured such that the sound signal output from the virtual microphone 1102L, that is, err v1 (n) and the sound signal output from the virtual microphone 1102R, that is, err v2 (n) are used as multiple errors for the first adaptive algorithm execution unit 1114 of the first system, the first adaptive algorithm execution unit 1116 of the second system, the second adaptive algorithm execution unit 1124 of the first system, and the second adaptive algorithm execution unit 1126 of the second system.

[0166] In addition, in such a first learning processing unit 1100, the first adaptive algorithm execution unit 1114 of the first system updates the transfer function W 11 (z) of the first variable filter 1113 of the first system by the MEFX LMS algorithm so that err v1 (n) and err v2(n) is 0. Additionally, the first adaptive algorithm execution unit 1116 of the second system updates the transfer function W 12 (z) of the first variable filter 1115 of the second system such that err v1 (n) and err v2 (n) are 0. Also, the second adaptive algorithm execution unit 1124 of the first system updates the transfer function W 21 (z) of the second variable filter 1123 of the first system such that err v1 (n) and err v2 (n) are 0. Furthermore, the second adaptive algorithm execution unit 1126 of the second system updates the transfer function W 22 (z) of the second variable filter 1125 of the second system such that err v1 (n) and err v2 (n) are 0.

[0167] In addition, in the configuration of the virtual microphone 1102L to the first cancellation point and the configuration of the virtual microphone 1102R to the second cancellation point, for example, a virtual head equipped with the virtual microphones 1102L and 1102R is used. Additionally, the first learning processing unit 1100 is realized, for example, by the learning control unit 505 of the control unit 220 rewriting the program of the DSP constituting the signal processing unit 210.

[0168] In addition, in the first-stage learning process using such a first learning processing unit 1100, the noise signal x1(n) and the noise signal x2(n) are input to the first learning processing unit 1100. Additionally, in this state, wait for the transfer function W 11 (z) of the first variable filter 1113 of the first system, the transfer function W 12 (z) of the first variable filter 1115 of the second system, the transfer function W 21 (z) of the second variable filter 1123 of the first system, and the transfer function W 22 (z) of the second variable filter 1125 of the second system to converge. Furthermore, if each transfer function converges, then obtain each transfer function W 11 (z), W 12 (z), W 21 (z), and W 22 (z).

[0169] Here, as Figure 11 shown, let the transfer function up to the output of the virtual microphone 1102L of the noise signal x1(n) be V 11(z), let the transfer function up to the output of the virtual microphone 1102R of the noise signal x1(n) be V 12 (z). Additionally, let the transfer function up to the output of the virtual microphone 1102L of the noise signal x2(n) be V 21 (z), let the transfer function up to the output of the virtual microphone 1102R of the noise signal x2(n) be V 22 (z). Furthermore, let the transfer function up to the output of the virtual microphone 1102L of the cancellation signal CA1(n) be S V11 (z), let the transfer function up to the output of the virtual microphone 1102R of the cancellation signal CA1(n) be S V12 (z).

[0170] Additionally, let the transfer function up to the output of the virtual microphone 1102L of the cancellation signal CA2(n) be S V21 (z), let the transfer function up to the output of the virtual microphone 1102R from the cancellation signal CA2(n) be S V22 (z). Furthermore, if the Z-transform of x i (n) is x i (z), and the Z-transform of errv i (n) is errv i (z), then the err v1 (z) output by the virtual microphone 1102L is

[0171] Equation 1

[0172] err v1 (z) = x1(z)V 11 (z) + {x1(z)W 11 (z) + x2(z)W 21 (z)}Sv 11 (z) + {x1(z)W 12 (z) + x2(z)W 22 (z)}S v21 (z) + x2(z)V 21 (x)

[0173] = x1(z){V 11 (z) + W 11 (z)S v11 (z) + W 12 (z)S v21 (z)} + x2(z){V 21 (x) + W 21 (x))S v11 (z) + W 22 (z)S v21 (z)},

[0174] The err output by the virtual microphone 1102R v2 (z) is similarly

[0175] Equation 2

[0176] err v2 (z) = x1(z) {V 12 (z) + W 11 (z) S v12 (z) + W 12 (z) S v22 (z)} + x2(z) {V 22 (x) + W 21 (x) S v12 (z) + W 22 (z) S v22 (z)}.

[0177] Here, since x1(z) ≠ 0 and x2(z) ≠ 0, so err v1 (z) = 0, errv2(z) = 0 is as follows

[0178] Equation 3

[0179] {V 11 (z) + W 11 (z) S v11 (z) + W 12 (z) S v21 (z)} = 0

[0180] {V 21 (x) + W 21 (x) S v11 (z) + W 22 (z) S v21 (z)} = 0

[0181] {V 12 (z) + W 11 (z) S v12 (z) + W 12 (z) S v22 (z)} = 0

[0182] {V 22 (x) + W 21 (x) S v12 (z) + W 22 (z) S v22 (z)} = 0

[0183] When, regarding W 11 、W 12 、W 21 and W 22When solving simultaneous equations, it becomes

[0184] Equation 4

[0185] W 11 = {V 12 (z)S v21 (z) - V 11 (z)S v22 (z)} / {S v11 (z)S v22 (z) - S v12 (z)S v21 (z)}

[0186] W 12 = {V 11 (z)S v12 (z) - V 12 (z)S v11 (z)} / {S v11 (z)S v22 (z) - S v12 (z)S v21 (z)}

[0187] W 21 = {V 22 (z)S v21 (z) - V 21 (z)S v22 (z)} / {S v11 (z)S v22 (z) - S v12 (z)S v21 (z)}

[0188] W 22 = {V 21 (z)S v12 (z) - V 22 (z)S v11 (z)} / {S v11 (z)S v22 (z) - S v12 (z)S v21 (z)},

[0189] In the first learning processing unit 1100, the transfer functions W 11 (z), W 12 (z), W 21 (z), W 22 (z) converge to this value.

[0190] In addition, the converged transfer functions W 11 , W 12 , W 21 , W 22The value is the value for eliminating the noise generated by the first noise source 201 and the noise generated by the second noise source 202 at the first cancellation point and the second cancellation point.

[0191] And, if the transfer functions W 11 (z), W 12 (z), W 21 (z), W 22 (z) that converge in the learning process of the first stage using such a first learning processing unit 1100 are obtained, the learning process of the first stage is terminated, and the learning process of the second stage is performed.

[0192] Figure 12 FIG. is a diagram showing a configuration example of the second learning processing unit according to an embodiment. As Figure 12 shown, the learning process of the second stage is performed in a configuration in which the signal processing unit 210 of the noise reduction system 1 is replaced with the second learning processing unit 60. Here, as Figure 12 shown, the second learning processing unit 60 has a configuration in which the first adaptive algorithm execution unit 1114 of the first system, the first adaptive algorithm execution unit 1116 of the second system, the second adaptive algorithm execution unit 1124 of the first system, and the second adaptive algorithm execution unit 1126 of the second system are omitted from the signal processing unit 210 shown in Figure 3 FIG.

[0193] And, as Figure 12 shown, the first variable filter 1113 of the first system is replaced with the first fixed filter 61 of the first system in which the transfer function is fixed to the transfer function W 11 (z) obtained in the first learning process. In addition, the first variable filter 1115 of the second system is replaced with the first fixed filter 62 of the second system in which the transfer function is fixed to the transfer function W 12 (z) obtained in the first learning process. Further, the second variable filter 1123 of the first system is replaced with the second fixed filter 63 of the first system in which the transfer function is fixed to the transfer function W 21 (z) obtained in the first learning process. Further, the second variable filter 1125 of the second system is replaced with the second fixed filter 64 of the second system in which the transfer function is fixed to the transfer function W 22 (z) obtained in the first learning process.

[0194] In addition, in the second learning processing unit 60, as Figure 12 shown, Figure 3The first auxiliary filter 1111 of the first system in the signal processing unit 210 shown is replaced with the first variable auxiliary filter 71 of the first system. Further, there is provided a first learning first adaptive algorithm execution unit 81 of the first system that updates the transfer function H 11 (z) of the first variable auxiliary filter 71 of the first system by the FXLMS algorithm.

[0195] In addition, in the second learning processing unit 60, the first auxiliary filter 1112 of the second system is replaced with the first variable auxiliary filter 72 of the second system. Further, there is provided a second learning first adaptive algorithm execution unit 82 of the second system that updates the transfer function H 12 (z) of the first variable auxiliary filter 72 of the second system by the FXLMS algorithm.

[0196] In addition, in the second learning processing unit 60, the second auxiliary filter 1121 of the first system is replaced with the second variable auxiliary filter 73 of the first system. Further, there is provided a second learning second adaptive algorithm execution unit 83 of the first system that updates the transfer function H 21 (z) of the second variable auxiliary filter 73 of the first system by the FXLMS algorithm.

[0197] In addition, in the second learning processing unit 60, the second auxiliary filter 1122 of the second system is replaced with the second variable auxiliary filter 74 of the second system. Further, there is provided a second learning second adaptive algorithm execution unit 84 of the second system that updates the transfer function H 22 (z) of the second variable auxiliary filter 74 of the second system by the FXLMS algorithm.

[0198] In addition, in the second learning processing unit 60, the error signal err h1 (n) output by the error correction adder 1117 of the first system is output as an error to the first learning first adaptive algorithm execution unit 81 and the second learning second adaptive algorithm execution unit 83 of the first system. Further, it is configured such that the error signal err h2 (n) output by the error correction adder 1127 of the second system is output as an error to the first learning first adaptive algorithm execution unit 82 and the second learning second adaptive algorithm execution unit 84 of the second system.

[0199] Then, the first learning first adaptive algorithm execution unit 81 of the first system updates the transfer function H 11 (z) of the first variable auxiliary filter 71 of the first system by the FXLMS algorithm so that the error signal err h1(n) becomes 0. Additionally, the first adaptive algorithm execution unit 82 for learning of the second system updates the transfer function H 12 (z) of the first variable auxiliary filter 72 of the second system such that the error signal err h2 (n) input as an error becomes 0.

[0200] In addition, the second adaptive algorithm execution unit 83 for learning of the first system updates the transfer function H 21 (z) of the second variable auxiliary filter 73 of the first system such that the error signal err h1 (n) input as an error becomes 0. Furthermore, the second adaptive algorithm execution unit 84 for learning of the second system updates the transfer function H 22 (z) of the second variable auxiliary filter 74 of the second system such that err h2 (n) input as an error becomes 0. Additionally, the second learning processing unit 60 is realized, for example, by the learning control unit 505 of the control unit 220 rewriting the program of the DSP constituting the signal processing unit 210 and the like.

[0201] In addition, in the second-stage learning process using such a second learning processing unit 60, the noise signal x1(n) and the noise signal x2(n) are input to the second learning processing unit 60. Additionally, in this state, wait for the transfer function H 11 of the first variable auxiliary filter 71 of the first system, the transfer function H 12 (z) of the first variable auxiliary filter 72 of the second system, the transfer function H 21 (z) of the second variable auxiliary filter 73 of the first system, and the transfer function H 22 (z) of the second variable auxiliary filter 73 of the second system to converge. Furthermore, if each transfer function converges, then obtain each transfer function H 11 (z), H 12 (z), H 21 (z), and H 22 (z).

[0202] Here, as Figure 12 shown, the transfer function up to the output of the microphone 112L of the noise signal x1(n) is set as P 11 (z), and the transfer function up to the output of the microphone 112R of the noise signal x1(n) is set as P 12 (z). Additionally, the transfer function up to the output of the microphone 112L of the noise signal x2(n) is set as P 21 (z), and the transfer function up to the output of the microphone 112R of the noise signal x2(n) is set as P 22(z). Also, let the transfer function up to the output of microphone 112L that eliminates signal CA1(n) be S P11 (z), and let the transfer function up to the output of microphone 112R that eliminates signal CA1(n) be S P12 (z).

[0203] In addition, let the transfer function up to the output of microphone 112L that eliminates signal CA2(n) be S P21 (z), and let the transfer function up to the output of microphone 112R that eliminates signal CA2(n) be S P22 (z). Furthermore, if the Z-transform of err pi (n) is err pi (z), and the Z-transform of err hi (n) is err hi (z), then err p1 (z) output by microphone 112L is

[0204] Equation 5

[0205] err P1 (z) = x1(z)P 11 (z) + {x1(z)W 11 (z) + x2(z)W 21 (x)}S p11 (z) + {x1(z)W 12 (z) + x2(z)W 22 (z)}S p21 (z) + x2(z)P 21 (x) = x1(z){P 11 (z) + W 11 (z)S p11 (z) + W 12 (z)S p21 (z)} + x2(z){P 21 (x) + W 21 (x)S p11 (z) + W 22 (z)S p21 (z)},

[0206] Similarly, err p2 (z) output by microphone 112R is

[0207] Equation 6

[0208] err P2 (z) = x1(z){P 12 (z) + W 11 (z)S p12 (z) + W12 (z)S p22 (z)}+x2(z){P 22 (x)+W 21 (x)S p12 (z)+W 22 (z)S p22 (z)}。

[0209] Therefore, when the error signal err h1 (n) output by the error correction adder 1117 of the first system is 0, it becomes

[0210] Equation 7

[0211] err h1 (z) = err p1 (z)+x1(z)H 11 (z)+x2(z)H 21 (z) = x1(z){P 11 (z)+W 11 (z)S p11 (z)+W 12 (z)S p21 (z)}+x2(z){P 21 (x)+W 21 (x)S p11 (z)+W 22 (z)S p21 (z)}+x1(z)H 11 (z)+x2(z)H 21 (z) = 0

[0212] In addition, similarly, when the error signal err h2 (n) is 0, it becomes

[0213] Equation 8

[0214] err h2 (z) = err p2 (z)+x1(z)H 12 (z)+x2(z)H 22 (z) = x1(z){P 12 (z)+W 11 (z)S p12 (z)+W 12 (z)S p22 (z)}+x2(z){P 22 (x)+W 21 (x)S p12 (z)+W 22 (z)S p22 (z)}+x1(z)H 12(z) + x2(z)H 22 (z) = 0

[0215] Here, x1(z) ≠ 0, x2(z) ≠ 0, so err h1 (z) = 0, err h2 (z) = 0 is at,

[0216] Equation 9

[0217] H 11 (z) = -{P 11 (z) + W 11 (z)S p11 (z) + W 12 (z)S p21 (z)}

[0218] H 12 (z) = -{P 12 (z) + W 11 (z)S p12 (z) + W 12 (z)S p22 (z)}

[0219] H 21 (z) = -{P 21 (x) + W 21 (x)S p11 (z) + W 22 (z)S p21 (z)}

[0220] H 22 (z) = -{P 22 (x) + W 21 (x)S p12 (z) + W 22 (z)S p22 (z)}

[0221] When substituting the transfer functions W 11 (z), W 12 (z), W 21 (z), W 22 (z) obtained in the first learning process and set for the first fixed filter 61 of the first system, the first fixed filter 62 of the second system, the second fixed filter 63 of the first system, and the second fixed filter 64 of the second system, it becomes,

[0222] Equation 10

[0223] H 11 (z) = -[P 11 (z) + {V 12 (z)S v21(z)-V11(z)S v22 (z)}S p11 (z)+{V 11 (z)S v12 (z)-V 12 (z)S v11 (z)}S p21 (z)] / [S v11 (z)S v22 (z)-S v12 (z)S v21 (z)]

[0224] H 12 (z)=-[P 12 (z)+{V 12 (z)S v21 (z)-V 11 (z)S v22 (z)}S p12 (z)+{V 11 (z)S v12 (z)-V 12 (z)S v11 (z)}S p22 (z)] / [S v11 (z)S v22 (z)-S v12 (z)S v21 (z)]

[0225] H 21 (z)=-[P 21 (x)+{V 22 (z)S v21 (z)-V 21 (z)S v22 (z)}S p11 (z)+{V 21 (z)S v12 (z)-V 22 (z)S v11 (z)}S p21 (z)] / [S v11 (z)S v22 (z)-S v12 (z)S v21 (z)]

[0226] H 22 (z)=-[P 22 (x)+{V 22 (z)S v21 (z)-V 21 (z)S v22 (z)}S p12 (z)+{V 21(z)S v12 (z)-V 22 (z)S v11 (z)}S p22 (z)] / [S v11 (z)S v22 (z)-S v12 (z)S v21 (z)],

[0227] In the second learning processing unit 60, the transfer functions H 11 (z), H 12 (z), H 21 (z), H 22 (z) converge to this value.

[0228] In addition, if the transfer functions H 11 (z), H 12 (z), H 21 (z), H 22 (z) that converge in the learning processing of the second stage using such a second learning processing unit 60 are obtained, the learning processing of the second stage is terminated.

[0229] Here, the transfer functions H 11 (z), H 12 (z) correct the differences between the transfer functions of each noise signal x1(n), x2(n), each cancellation signal CA1(n), CA2(n) from the first cancellation point to the position of the microphone 112L. Similarly, the transfer functions H 21 (z), H 22 (z) correct the differences between the transfer functions of each noise signal x1(n), x2(n), each cancellation signal CA1(n), CA2(n) from the second cancellation point to the position of the microphone 112R.

[0230] The transfer functions H 11 (z), H 12 (z), H 21 (z), H 22 (z) correspond to the "setting of the auxiliary filter" of the present embodiment as described above. In addition, Figure 3 The first auxiliary filter 1111 of the first system, the first auxiliary filter 1112 of the second system, the second auxiliary filter 1121 of the first system, and the second auxiliary filter 1122 of the second system correspond to the "auxiliary filter" of the present embodiment as described above.

[0231] By applying this "setting of the auxiliary filter" to the "auxiliary filter", for example, in Figure 2At the first cancellation point and the second cancellation point, it is possible to cancel the noise generated by the first noise source 201 and the second noise source 202.

[0232] The noise reduction device 100 performs the above-described learning process, for example, in a state where the speakers and microphones corresponding to the rear seats 103 and 104 that affect the noise of the driver's seat 101 are set to be valid, and stores the setting of the obtained auxiliary filter in advance as the setting of the auxiliary filter A. Further, the noise reduction device 100 performs the above-described learning process in a state where the speakers and microphones corresponding to one of the seats in the rear seats 103 and 104 that affect the noise of the driver's seat 101 are set to be invalid, and stores the setting of the obtained auxiliary filter in advance as the setting of the auxiliary filter B.

[0233] Preferably, the noise reduction device 100 also stores in advance the settings of the auxiliary filter A and the auxiliary filter B obtained through the same learning process for other seats in the vehicle 10.

[0234] As described above, the embodiments of the present invention have been described, but the present invention is not limited to the above-described embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims.

[0235] Explanation of reference numerals

[0236] 1 Noise reduction system

[0237] 10 Vehicle

[0238] 100 Noise reduction device

[0239] 210 Signal processing unit

[0240] 220 Control unit

[0241] 502 Operation setting unit

[0242] 503 Auxiliary filter setting unit

[0243] 1111 First auxiliary filter of the first system

[0244] 1112 First auxiliary filter of the second system

[0245] 1121 Second auxiliary filter of the first system

[0246] 1122 Second auxiliary filter of the second system

Claims

1. A noise reduction device uses speakers and microphones corresponding to each seat of a vehicle to reduce noise for each seat. The noise reduction device includes: The signal processing unit generates a cancellation sound that reduces noise at the position of the ears of the occupant on a specified seat by using an auxiliary filter, where The microphone corresponding to the specified seat is away from the occupant's ear. By setting a transfer function in the auxiliary filter, a sound signal at the position of the ear is virtually obtained, thereby reducing noise at the position of the ear. An operation setting unit that sets the operations of the speakers and microphones corresponding to the seats in the vehicle without occupants to be invalid. And An auxiliary filter setting unit that changes the transfer function of the auxiliary filter used by the signal processing unit in generating the cancellation sound according to the number of occupants on other seats that affect the noise of the specified seat as judged by the occupant determination unit.

2. The noise reduction device according to claim 1, wherein The auxiliary filter setting unit sets the following transfer function for the auxiliary filter used by the signal processing unit in generating the cancellation sound when there are occupants in each of the other seats. The transfer function is the transfer function of the auxiliary filter learned in a state where the operations of the speakers and microphones corresponding to each of the other seats are set to be effective.

3. The noise reduction device according to claim 1 or 2, wherein The auxiliary filter setting unit sets the following transfer function for the auxiliary filter used by the signal processing unit in generating the cancellation sound when there are occupants in a part of the other seats. The transfer function is the transfer function of the auxiliary filter learned in a state where the operations of the speakers and microphones corresponding to one of the other seats are set to be effective and the operations of the speakers and microphones corresponding to the other of the other seats are set to be invalid.

4. The noise reduction device according to claim 1 or 2, wherein When an occupant is sitting on the specified seat, The operation setting unit Sets the operation of the speaker corresponding to the specified seat to be effective, After setting the operation of the speaker to be effective or when setting the operation of the speaker to be effective, sets the operation of the microphone corresponding to the specified seat to be effective.

5. The noise reduction device according to claim 1 or 2, wherein The specified seat includes: a first speaker and a first microphone disposed near the left ear of the occupant, and a second speaker and a second microphone disposed near the right ear of the occupant, The signal processing unit generates a first cancellation sound for reducing noise at the position of the left ear of the occupant and a second cancellation sound for reducing noise at the position of the right ear of the occupant.

6. The noise reduction device according to claim 1 or 2, wherein The specified seat is the driver's seat or the front passenger seat of the vehicle, The other seats are the rear seats of the vehicle.

7. The noise reduction device according to claim 1 or 2, wherein The specified seat is one of the rear seats of the vehicle The other seats are the driver's seat and the front passenger seat of the vehicle.

8. A vehicle equipped with the noise reduction device according to any one of claims 1 to 7.

9. A noise reduction method, which is a noise reduction method executed by a noise reduction device. The noise reduction device uses speakers and microphones corresponding to each seat of a vehicle to reduce noise for each seat. The noise reduction method performs the following processes: The signal processing unit generates a cancellation sound that reduces noise at the position of the ears of the occupant in a specified seat, using the set auxiliary filter, wherein, The microphone corresponding to the specified seat is moved away from the ear of the occupant, and by setting a transfer function in the auxiliary filter, a sound signal at the position of the ear is virtually obtained, thereby reducing noise at the position of the ear; Set the operations of the speakers and microphones corresponding to the seats in the vehicle that have no occupants to be invalid; And According to the number of occupants on other seats that affect the noise of the specified seat as judged by the occupant determination unit, change the transfer function of the auxiliary filter used in the generation of the cancellation sound.

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