Noise reduction system for railway vehicles

Abstract

The present invention is a noise reduction system 1 for a railway vehicle for reducing, at a plurality of silencing positions 10 in a railway vehicle 100, noise propagated from a noise source in the exterior of the railway vehicle 100, the plurality of silencing positions 10 being positions that are different in the longitudinal direction of the vehicle, the noise reduction system 1 for a railway vehicle comprising a noise reference sensor 20 for detecting noise propagated from the noise source and / or vibration caused by the noise, and a plurality of silencing devices 30 for respectively reducing noise at each of the plurality of silencing positions 10. Each silencing device 30 is provided with a speaker 31 for emitting sound at the respective silencing position 10 and a control unit 32 for outputting a control signal to cause the speaker 31 to radiate sound such that noise at the respective silencing position 10 is reduced. The noise reference sensor 20 is installed at the same position as, or at a position farther to the front of the vehicle than, the silencing position 10 that is located farthest to the front of the vehicle from among the plurality of silencing positions 10, with respect to the longitudinal direction of the vehicle. Each of the plurality of control units 32 generates the control signal using a reference signal outputted from the noise reference sensor 20.

Description

Technical Field

[0001] The present invention relates to a noise reduction system for railway vehicles.

Background Art

[0002] Patent Document 1 discloses a noise reduction device including a control sound source, an error detector, and a control unit. This noise reduction device operates to cancel out noise by controlling the control sound source to generate a sound having an opposite phase and the same sound pressure as the noise at the position of the error detector. Further, it discloses that a noise detector for detecting noise outside the space where the error detector is arranged is further arranged, a control signal is generated based on the detection results of the error detector and the noise detector, and the control signal is output to the control sound source (FIGS. 14 and 15). And it is also disclosed that the speaker as the control sound source is configured using a glass window (paragraph

[0129] ).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the noise reduction device of Patent Document 1, when detecting sound only by the error detector, there is a limit to the types of signals that can be obtained only by the error detector, and there is a problem that the accuracy of noise reduction is poor. On the other hand, by arranging a noise detector in addition to the error detector, the types of signals that can be obtained increase, and accurate noise reduction can be realized. However, there is a problem that when both an error detector and a noise detector are arranged in the noise reduction device, the noise reduction device becomes large-sized.

[0005] Particularly when introducing the noise reduction device of Patent Document 1 to a railway vehicle, it is necessary to provide a noise reduction device for each of a plurality of noise reduction points. However, if both an error detector and a noise detector are arranged in all the noise reduction devices, the installation space of the entire system will increase significantly.

[0006] The present invention has been made to solve the above problems, and an object thereof is to provide a noise reduction system for railway vehicles that can achieve accurate noise reduction while reducing the installation space.

Means for Solving the Problems

[0007] The noise reduction system for railway vehicles of the present invention is a noise reduction system for railway vehicles that reduces noise propagated from a noise source outside the railway vehicle at a plurality of noise reduction points inside the railway vehicle. The plurality of noise reduction points are different points in the vehicle longitudinal direction. The noise reduction system for railway vehicles includes a noise reference sensor that detects at least one of the noise propagated from the noise source and the vibration caused by the noise, and a plurality of noise reduction devices that respectively reduce the noise at the plurality of noise reduction points. Each of the plurality of noise reduction devices includes a speaker that emits sound at the noise reduction point, and a control unit that outputs a control signal for radiating sound to the speaker so that the noise at the noise reduction point becomes small. The noise reference sensor is installed at the same position as the noise reduction point that is the most forward in the vehicle longitudinal direction among the plurality of noise reduction points, or in front of the noise reduction point in the vehicle longitudinal direction. The plurality of control units respectively generate the control signal using the reference signal output from the noise reference sensor.

Effects of the Invention

[0008] According to the present invention, it is possible to provide a noise reduction system for railway vehicles that can achieve accurate noise reduction while reducing the installation space.

Brief Description of the Drawings

[0009]

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DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, the noise reduction system for a railway vehicle of the present invention will be described. However, the present invention is not limited to the following configurations, and can be appropriately changed and applied without changing the gist of the present invention. In addition, combinations of two or more of the individual desirable configurations described below are also within the scope of the present invention.

[0011] Also, each of the embodiments shown below is an example, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible. Repeated descriptions of common matters in multiple embodiments are omitted, and only the differences will be described.

[0012] In this specification, the "railway vehicle" means a vehicle (preferably a passenger car) that travels on a predetermined track (regardless of the material), and its power source is not particularly limited. Specifically, examples of railway vehicles include electric trains (including tramways, monorails, maglev railways, etc.), pneumatic cars, passenger cars of locomotives, and the like.

[0013] [Embodiment 1] FIG. 1 is a diagram schematically showing an example of a noise reduction system for a railway vehicle according to Embodiment 1 of the present invention.

[0014] The noise reduction system 1 for a railway vehicle shown in FIG. 1 is an ANC (Active Noise Control) system installed in the railway vehicle 100, which reduces the noise propagated from the noise source outside the railway vehicle 100 at a plurality of noise reduction points 10 inside the railway vehicle 100.

[0015] The railway vehicle 100 is composed of a plurality of vehicles 110, and a plurality of windows 120 are provided on one side of each vehicle 110. The positions of the plurality of windows 120 in the vehicle front-rear direction are different from each other.

[0016] Note that a plurality of windows are similarly provided on the other side of each vehicle 110, and a noise reduction device described later is similarly provided for each of these windows. However, since these configurations are common on one side and the other side of the railway vehicle 100, the description of the configuration on the other side of the railway vehicle 100 is omitted.

[0017] In this specification, the "vehicle front-rear direction" corresponds to the traveling direction of the railway vehicle and the opposite direction thereof. That is, "vehicle front" corresponds to the traveling direction of the railway vehicle, and "vehicle rear" corresponds to the direction opposite to the traveling direction of the railway vehicle. Also, "one side and the other side" respectively mean one and the other sides with respect to the traveling direction of the railway vehicle.

[0018] The noise reduction location 10 is a location where the noise propagated from the noise source is mainly reduced, and a plurality of noise reduction locations 10 are set at different locations in the vehicle longitudinal direction. Here, they are respectively set corresponding to a plurality of windows 120 of the railway vehicle 100 whose positions in the vehicle longitudinal direction are different from each other.

[0019] The railway vehicle noise reduction system 1 includes a noise reference sensor 20 and a plurality of noise reduction devices 30.

[0020] The noise reference sensor 20 is a reference signal acquisition sensor that detects at least one of the noise propagated from the noise source and the vibration caused by the noise, and outputs the detection result as a reference signal. Here, as the noise reference sensor 20, a microphone (noise reference microphone) that detects the noise propagated from the noise source is installed.

[0021] Note that the noise reference sensor 20 is not particularly limited to a microphone, and may be, for example, a vibration sensor that detects the vibration caused by the noise propagated from the noise source. In this case, the vibration sensor may be installed on the window 120 of the railway vehicle 100, and the vibration of the window 120 generated according to the noise may be detected by the vibration sensor.

[0022] The noise reference sensor 20 is installed at the same position as the noise reduction location 10 that is the most forward in the vehicle longitudinal direction among the plurality of noise reduction locations 10, or in front of that noise reduction location 10 in the vehicle longitudinal direction. Thus, the noise reference sensor 20 is installed on the leading vehicle 110. Also, in the present embodiment, the noise reference sensor 20 is installed only at the same position as the noise reduction location 10 that is the most forward in the vehicle longitudinal direction, that is, only at the leading window 120 of the leading vehicle 110.

[0023] The plurality of noise reduction devices 30 are respectively devices that reduce the noise at the plurality of noise reduction locations 10, and one noise reduction device 30 is provided for each noise reduction location 10.

[0024] Each noise reduction device 30 includes a speaker 31 (for example, a transparent flat panel speaker 31a described later) and a control unit (control circuit) 32. Note that all the noise reduction devices 30 have the same configuration.

[0025] Each speaker 31 emits sound to the noise reduction point 10 (the noise reduction point 10 that is the target of noise reduction of the noise reduction device 30 including that speaker 31).

[0026] Each control unit 32 is connected to the speaker 31 and outputs a control signal for causing the speaker 31 to emit sound so that the noise at the noise reduction point 10 (the noise reduction point 10 that is the target of noise reduction of the noise reduction device 30 including that control unit 32) is reduced. Specifically, the control signal is output so that the speaker 31 generates a sound having a reverse phase and the same sound pressure as the noise at the noise reduction point 10.

[0027] In addition, each control unit 32 is connected to the noise reference sensor 20 and generates a control signal using the reference signal output from the noise reference sensor 20. That is, the reference signal of the noise reference sensor 20 obtained in front of the vehicle is used for a plurality of noise reduction devices 30 for a plurality of noise reduction points 10 that are the same as or located more rearward of the noise reference sensor 20 in the vehicle longitudinal direction. Therefore, it is not necessary to install a noise reference sensor 20 at each noise reduction point 10 (each window 120), and the installation space of the railway vehicle noise reduction system 1 can be reduced. Further, it leads to an improvement in the degree of freedom of installation and cost reduction of the railway vehicle noise reduction system 1. Furthermore, since each noise reduction device 30 uses the reference signal of the noise reference sensor 20, accurate noise reduction can be achieved.

[0028] Even if the location where the reference signal is acquired is different from the location of the noise reduction point 10, the railway vehicle 100 is moving at a high speed, and basically the same noise (for example, the noise when passing through a rail joint or the noise when entering a tunnel) enters each noise reduction point 10. Therefore, it is possible to use (reproduce) the reference signal at each noise reduction point 10. That is, based on the running speed of the railway vehicle 100 and the distance between the noise reference sensor 20 (reference signal acquisition point) and each noise reduction point 10 (hereinafter sometimes referred to as the inter-point distance), the reference signal can be processed (corrected) and used. Specifically, by passing through a filter that takes into account the running speed of the railway vehicle 100, the inter-point distance, and the acoustic characteristics of each noise reduction point 10, the reference signal at each noise reduction point 10 is reproduced.

[0029] FIG. 2 is a block diagram showing an example of the configuration of the noise reduction system for railway vehicles shown in FIG. 1.

[0030] As shown in FIG. 2, the noise reduction system 1 for railway vehicles includes a reference signal processing device 40 that processes the reference signal output from the noise reference sensor 20 in order to appropriately process the reference signal and propagate it to each noise reduction point 10, and a plurality of delay devices 50 and a plurality of error sensors 60 respectively connected to the plurality of noise reduction devices 30.

[0031] The reference signal processing device 40 receives the reference signal acquired from the noise reference sensor 20 and the speed information indicating the running speed of the railway vehicle 100. The reference signal processing device 40 is composed of an acoustic filter 41 that takes into account the acoustic characteristics of each noise reduction point 10, a signal amplifier 42, a delay device 43, etc. for reproducing the reference signal. The reference signal processed by the reference signal processing device 40 is input to the noise reduction device 30 (noise reduction device 1~n ) of each noise reduction point 10. At this time, it passes through a delay device 50 (delay device 1~n ) with a delay amount calculated from the distance from the position where the reference signal was acquired to each noise reduction point 10. Note that n represents an integer of 2 or more.

[0032] FIG. 3 is a flowchart showing an example of signal processing by the noise reduction system for railway vehicles shown in FIG. 1.

[0033] As shown in FIG. 3, in the noise reduction system 1 for railway vehicles, first, the noise reference sensor 20 acquires a reference signal (S01), the acquired reference signal is processed by the acoustic filter 41 (S02), and the reference signal processed by the acoustic filter 41 is amplified by the signal amplifier 42 (S03).

[0034] In parallel therewith, the reference signal processing device 40 acquires speed information (S04), and each error sensor 60 acquires an error signal (S05).

[0035] Then, the reference signal processing device 40 calculates a delay time based on the speed information (S06), and the delay device 43 delays the amplified reference signal by the calculated delay time (S07). Note that this delay time is inversely proportional to the running speed of the railway vehicle 100. That is, this delay time is shorter as the running speed of the railway vehicle 100 is higher, and longer as the running speed of the railway vehicle 100 is lower.

[0036] The delayed reference signal is further delayed by the delay device 50 for each window 120 (each noise reduction point 10) (S08). Note that the delay time by this delay device 50 is calculated by the delay device 50 based on the previously measured distance between each point and the speed information. This delay time is proportional to the distance between points and inversely proportional to the running speed of the railway vehicle 100. That is, this delay time is shorter when the distance between points is short and the running speed of the railway vehicle 100 is high, and longer when the distance between points is long and the running speed of the railway vehicle 100 is low.

[0037] Thereafter, the control unit 32 of each noise reduction device 30 generates a control signal based on the reference signal input from the delay device 50 and the error signal input from the error sensor 60 (S09), and outputs the generated control signal to the speaker 31 (S10). By generating the control signal based on not only the reference signal but also the error signal, the types of signals that can be acquired increase, so that more accurate noise reduction can be realized.

[0038] In addition, each control unit 32 may have any configuration as long as it controls the speaker 31 so that the sound detected by the error sensor 60 becomes as small as possible. For example, similar to the noise reduction device of Patent Document 1, it may include an FX filter (filtered X filter), a coefficient updater, and an adaptive filter. In this case, a reference signal is input to the FX filter from the corresponding delay unit 50, and the characteristics of the FX filter are set to be equivalent to the transfer function from the speaker 31 to the error sensor 60. An error signal is input to the coefficient updater from the corresponding error sensor 60, and the output signal of the FX filter is also input. An output signal (filter coefficient described later) from the coefficient updater and a reference signal output from the corresponding delay unit 50 are input to the adaptive filter, and a control signal is output based on these signals. The coefficient updater is composed of an LMS (Least Mean Square) algorithm or the like, and performs arithmetic processing to update the filter coefficient of the adaptive filter so that the error input from the error sensor 60 is always reduced. Then, the adaptive filter generates a control signal based on the filter coefficient updated by the coefficient updater, and outputs the generated control signal to the speaker 31.

[0039] In this specification, each signal and its processing may be a digital signal and digital signal processing, or an analog signal and analog signal processing. Also, some signals and their processing may be analog signals and analog signal processing, while other signals and their processing may be digital signals and digital signal processing.

[0040] In this embodiment, the plurality of sound deadening devices 30 are respectively provided for a plurality of windows 120 having different positions in the vehicle longitudinal direction. Thereby, it is possible to more effectively reduce the noise propagated from the noise source outside the railway vehicle 100. This is because the noise from the outside easily enters the inside of the railway vehicle 100 through the window 120.

[0041] FIG. 4 is a schematic cross-sectional view showing an example of the configuration of a noise reduction device for the front window where the noise reference sensor is installed in the noise reduction system for railway vehicles shown in FIG. 1. FIG. 5 is a schematic cross-sectional view showing an example of the configuration of a noise reduction device for a window where the noise reference sensor is not installed in the noise reduction system for railway vehicles shown in FIG. 1.

[0042] As shown in FIGS. 4 and 5, each window 120 of the railway vehicle 100 includes an external window glass 121 and a window frame 122 that supports the window glass 121.

[0043] The noise reference sensor 20 is installed only for the front window 120. For example, it is installed inside the lower part (inside the vehicle) of the window glass 121 of the front window 120. Note that the specific location of the noise reference sensor 20 installed for the window 120 is not particularly limited, but from the viewpoint of improving the accuracy of the reference signal, it is preferably installed at the center of the window glass 121.

[0044] The noise reduction device 30 is provided for each window 120 and may include a transparent flat speaker 31a as a speaker 31. The transparent flat speaker 31a is fitted into the window frame 122 inside the window glass 121.

[0045] The error sensor 60 is provided for each noise reduction point 10 (each window 120). For example, it is installed inside the lower part (inside the vehicle) of the transparent flat speaker 31a.

[0046] The error sensor 60 is an error signal acquisition sensor that detects at least one of sound and vibration at the noise reduction point 10 and outputs the detection result as an error signal. Here, as the error sensor 60, a microphone (error microphone) that detects sound at the noise reduction point 10 is installed.

[0047] Note that the error sensor 60 is not particularly limited to a microphone, and for example, it may be a vibration sensor that detects vibration at the noise cancellation point 10. In this case, the vibration sensor may be installed on the window frame 122 near the transparent flat panel speaker 31a, and the vibration of the window frame 122 may be detected by the vibration sensor.

[0048] Then, the reference signal output from the noise reference sensor 20 is input to the control unit 32 of each noise cancellation device 30 through the above-described signal processing, and the error signal output from the error sensor 60 is input to the control unit 32 of each noise cancellation device 30. Further, each control unit 32 generates a control signal based on the reference signal and the error signal, outputs it to the speaker 31, and the speaker 31 emits sound at the noise cancellation point 10 based on the control signal. As a result, at the noise cancellation point 10, the external noise and the sound from the speaker 31 interfere with each other and cancel each other out, thereby reducing the noise. Here, the noise may be reduced by directly canceling the vibration of the transparent flat panel speaker 31a with a control signal without causing the speaker 31 to emit sound.

[0049] Note that at least one error sensor 60 may be provided for the entire railway vehicle 100, and as shown in FIGS. 4 and 5, it may be provided for each noise cancellation device 30, or one may be provided for a plurality of noise cancellation devices 30. In the latter case, for example, one may be provided for each vehicle of the railway vehicle 100, or only one may be provided for a plurality of adjacent noise cancellation points 10, and the error signal from the error sensor 60 may be used by the plurality of noise cancellation devices 30. Further, in the latter case, the error signal may be appropriately corrected and used according to the distance between the error sensor 60 (error signal acquisition point) and each noise cancellation point 10.

[0050] [Embodiment 2] FIG. 6 is a diagram schematically showing an example of a noise reduction system for a railway vehicle according to Embodiment 2 of the present invention.

[0051] In the noise reduction system 2 for railway vehicles according to the present embodiment shown in FIG. 6, the noise reference sensor 20 is installed at a location other than the window 120 of the railway vehicle 100. In this case, the noise reference sensor 20 may be changed to a larger and higher-performance one than when it is installed on the window 120. Further, as the noise reference sensor 20, a microphone and a vibration sensor may be used in combination.

[0052] By not installing the noise reference sensor 20 on the window 120, the components can be reduced in all the windows 120. As a result, the transparent flat speaker 31a can be installed closer to the window glass, and a thinner structure can be achieved.

[0053] In the window 120 where the noise reference sensor 20 is not provided, the transparent flat speaker 31a can be installed closer to the window glass 121, and a thinner structure can be achieved.

[0054] Further, by changing the noise reference sensor 20 to a higher-performance one or using a microphone and a vibration sensor in combination, the accuracy of the obtained reference signal can be improved. As a result, the effect of noise reduction can be improved.

[0055] Even when the measurement environments of the point where the reference signal is acquired and the sound deadening point 10 are different, it is possible to use (reproduce) the reference signal at each sound deadening point 10 in the same manner as in the case of the first embodiment. Specifically, the reference signal at each sound deadening point 10 is reproduced by passing it through a filter considering the running speed of the railway vehicle 100, the distance between points, and the acoustic characteristics of each sound deadening point 10. Further, for the reproduction of the reference signal, other signal processing devices such as a signal amplifier and a delay device may be interposed.

[0056] In Embodiments 1 and 2, the case where only one noise reference sensor 20 is installed for the entire railway vehicle 100, specifically, only on the leading vehicle 110, has been described. However, in these embodiments, the noise reference sensor 20 may be installed one by one for each vehicle of the railway vehicle 100. In this case, the railway vehicle noise reduction system 1 or 2 may be constructed for each vehicle. Further, a plurality of noise reference sensors 20 may be installed for the entire railway vehicle 100, and may be installed one by one for a plurality of vehicles.

[0057] [Embodiment 3] FIG. 7 is a diagram schematically showing an example of a railway vehicle noise reduction system according to Embodiment 3 of the present invention.

[0058] In the railway vehicle noise reduction system 3 according to the present embodiment shown in FIG. 7, the noise reference sensors 20 are installed in a plurality of windows 120 of the railway vehicle 100.

[0059] More specifically, the railway vehicle 100 includes, as the vehicle 110, a first vehicle 110a and a second vehicle 110b located rearward of the first vehicle 110a in the vehicle direction. The first vehicle 110a includes a plurality of first windows 120a having different positions in the vehicle longitudinal direction as the windows 120, and the second vehicle 110b includes a plurality of second windows 120b having different positions in the vehicle longitudinal direction as the windows 120. The noise reference sensors 20 are respectively installed in the plurality of first windows 120a of the first vehicle 110a.

[0060] Further, a plurality of sound absorption devices 30 are respectively provided for the plurality of first windows 120a and the plurality of second windows 120b, and each reference signal output from the plurality of noise reference sensors 20 installed in the plurality of first windows 120a is used (input) for the sound absorption device 30 provided for the second window 120b having the same position in the vehicle interior as the first window 120a in which the noise reference sensor 20 is installed.

[0061] In this way, by installing the noise reference sensors 20 on a plurality of windows 120, it is possible to correct the error of the reference signal due to the installation position of the window 120 and the difference in the vehicle shape around the window 120. Thereby, the effect of noise reduction can be improved.

[0062] Here, that the positions in the vehicle are the same between the first window 120a and the second window 120b more specifically means, for example, (1) when the first window 120a and the second window 120b are respectively provided at corresponding positions of the first vehicle 110a and the second vehicle 110b, and the first window 120a and the second window 120b are corresponding windows to each other; (2) when each vehicle is evenly divided into a plurality of regions in the vehicle longitudinal direction, the case where the first window 120a exists within the region corresponding to the second window 120b, and the like.

[0063] In the present embodiment, the reference signal output from each noise reference sensor 20 is also used (input) for the soundproofing device 30 provided for the first window 120a where the noise reference sensor 20 is installed.

[0064] Also, in the present embodiment, each reference signal output from the plurality of noise reference sensors 20 installed on the plurality of first windows 120a may be used for the soundproofing device 30 provided for the second window 120b having substantially the same shape as the first window 120a where the noise reference sensor 20 is installed.

[0065] Note that, in each embodiment, the case where the railway vehicle 100 is formed of two cars is shown, but the railway vehicle 100 may have three or more cars, and a system similar to that of the second car may be constructed for the cars after the third car.

[0066] In each embodiment, each noise reduction point 10 and each noise reduction device 30 are provided with respect to the window 120 of the vehicle 110. However, each noise reduction point 10 and each noise reduction device 30 may be provided with respect to a plurality of locations other than the window 120 of the vehicle 110, for example, a plurality of locations on the wall or ceiling. Further, the noise reduction point 10 and the noise reduction device 30 may be provided with respect to different members of the vehicle, such as the window and the wall of the vehicle. In that case, it is preferable to process the reference signal with a filter considering the material of the installation location.

Explanation of Signs

[0067] 1, 2, 3 Noise reduction system for railway vehicles 10 Noise reduction point 20 Noise reference sensor 30 Noise reduction device 31 Speaker 31a Transparent flat speaker 32 Control unit 40 Reference signal processing device 41 Acoustic filter 42 Signal amplifier 43 Delay device 50 Delay device 60 Error sensor 100 Railway vehicle 110 Vehicle 110a First vehicle 110b Second vehicle 120 Window 120a First window 120b Second window 121 Window glass 122 Window frame

Claims

1. A noise reduction system for a railway vehicle that reduces noise propagated from a noise source outside the railway vehicle at a plurality of noise reduction points inside the railway vehicle, wherein the plurality of noise reduction points are different points in the longitudinal direction of the vehicle, the noise reduction system for the railway vehicle includes a noise reference sensor that detects at least one of the noise propagated from the noise source and the vibration caused by the noise, and a plurality of noise reduction devices that respectively reduce the noise at the plurality of noise reduction points, each of the plurality of noise reduction devices includes a speaker that emits sound at the noise reduction point, and a control unit that outputs a control signal for causing the speaker to emit sound so that the noise at the noise reduction point is reduced, the noise reference sensor is installed at the same position as the noise reduction point that is the most forward in the longitudinal direction of the vehicle among the plurality of noise reduction points, or in front of the noise reduction point in the longitudinal direction of the vehicle, and the plurality of control units respectively generate the control signal using a reference signal output from the noise reference sensor. A noise reduction system for a railway vehicle.

2. The noise reduction system for a railway vehicle according to claim 1, wherein the plurality of noise reduction devices are respectively provided for a plurality of windows of the railway vehicle that are different from each other in the longitudinal direction of the vehicle.

3. The noise reduction system for a railway vehicle according to claim 1 or 2, wherein the noise reference sensor is installed at a location other than the window of the railway vehicle.

4. The noise reduction system for a railway vehicle according to claim 1 or 2, wherein only one noise reference sensor is installed for the entire railway vehicle, or one noise reference sensor is installed for each vehicle of the railway vehicle.

5. The railway vehicle includes a first vehicle and a second vehicle located behind the first vehicle in the longitudinal direction of the vehicle, the first vehicle includes a plurality of first windows that are different from each other in the longitudinal direction of the vehicle, the second vehicle includes a plurality of second windows that are different from each other in the longitudinal direction of the vehicle, the noise reference sensor is installed in each of the plurality of first windows, the plurality of noise reduction devices are respectively provided for the plurality of first windows and the plurality of second windows, and each reference signal output from the plurality of noise reference sensors installed in the plurality of first windows is used for a noise reduction device provided for a second window having the same position in the vehicle as the first window in which the noise reference sensor is installed. The noise reduction system for a railway vehicle according to claim 1 or 2.

6. The noise reduction system for a railway vehicle according to claim 1 or 2, which processes the reference signal output from the noise reference sensor based on the running speed of the railway vehicle and the distance between the noise reference sensor and each noise reduction point.

7. Comprising an error sensor for detecting at least one of sound and vibration at any one of the plurality of noise reduction points, The plurality of control units each generate the control signal by using an error signal output from the error sensor in addition to the reference signal, the noise reduction system for a railway vehicle according to claim 1 or 2.

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