JP2000020072A - Silencer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve silencing effect in a cabin with an active noise controller having a control sound source, noise detecting means for detecting noise, noise control effect detecting means and adaptive control means for driving the control sound source inside. SOLUTION: Single or plural reference sensors 31 for detecting pressure are installed as the noise detecting means in the cabin 8. The single or plural reference sensors which detect vibration are installed as the noise detecting means in the cabin 8. The plural sensors of different kinds are installed as the noise detecting means. A monitor microphone 33 and the reference sensors 31 are composed of the sensors of the same kind.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active silencer for attenuating noise in a cabin mounted so as to cover a driving section of a work vehicle.

[0002]

2. Description of the Related Art Conventionally, in a work vehicle such as a tractor, a combine, or a backhoe, noise detecting means is provided, the noise is detected by the noise detecting means, and a vibration having an opposite phase to the detected noise is generated. Methods of providing and reducing the noise are well known. Conventionally, noise detection means is disposed near a noise source, such as an engine or a transmission case, and outputs a sound having an opposite phase to the noise from the work vehicle based on the noise detected by the noise detection means. The noise is output to the cabin so that the noise of the engine and the transmission case can be reduced in the cabin. For example, Japanese Utility Model Laid-Open No. 5-55198 and JP-A-8-7677
2 and so on.

[0003]

However, the noise detecting means is arranged near the transmission case or the engine, and reduces noise in the cabin by reducing the noise of the transmission case or the engine. is there. For this reason, it is difficult to suppress noise caused by the vibration characteristics of the entire cabin or noise caused by the material characteristics of members constituting the cabin. Further, it is difficult to suppress noise caused by sound field characteristics determined by the shape of the cabin itself. In addition, resin materials such as glass and dashboard are often used for the cabin,
There is a sound range of noise that is silenced by the sound insulation of the resin material. For this reason, the sound quality and frequency characteristics of the noise detected in the mission case or the vicinity of the engine and the noise in the cabin may be different, and it is difficult to suppress the noise. Further, the vicinity of the mission case or the engine is made of a hard material to support the mission case or the engine, and is covered by a bonnet or the like, so that a large amount of reverberation of the noise is transmitted to the cabin. Noise may cause an error. That is, it is difficult to identify noise that enters the cabin in the vicinity of the transmission case or the engine, and thus it is difficult to suppress the noise. Further, since the sound pressure is different between the noise detected by the noise detection means in the transmission case or the vicinity of the engine and the noise detected in the cabin, the sensitivity of the sensor must be changed between the noise detection and the noise reduction effect detection. In addition, it is necessary to use a detection means corresponding to the range of the sound pressure at which the noise is detected, that is, the dynamic range, and the same type of sensor cannot be used.

[0004]

The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described. That is, in a cabin attached to an aircraft having a noise source, a control sound source capable of generating a control sound, a noise detection unit for detecting the noise, a muffling effect detection unit for detecting a muffling effect by the control sound, An active noise control device comprising: an adaptive control unit that drives the control sound source based on a noise detection unit and a noise reduction effect detection unit based on a detection value of the noise reduction unit. A single or a plurality of sensors for detecting the pressure are installed as the noise detecting means in the inside. A control sound source capable of generating a control sound in a cabin attached to an airframe having a noise source; a noise detection unit detecting the noise; a muffling effect detection unit detecting a muffling effect by the control sound; An active noise control device comprising: an adaptive control unit that drives the control sound source based on a noise detection unit and a noise reduction effect detection unit based on a detection value of the noise reduction unit. A single sensor or a plurality of sensors for detecting vibration are installed as the noise detecting means on the member constituting the above. In addition, a control sound source capable of generating a control sound is provided in a cabin attached to an aircraft having a noise source,
A noise detection unit that detects the noise, a muffling effect detection unit that detects a muffling effect due to the control sound, and a detection value of the muffling effect detection unit is minimized based on the detection values of the noise detection unit and the muffling effect detection unit. In the active noise control device provided with an adaptive control means for driving the control sound source so as to satisfy the following condition, a plurality of sensors of different types are installed in the cabin as the noise detection means. A control sound source capable of generating a control sound in a cabin attached to an airframe having a noise source; a noise detection unit detecting the noise; a muffling effect detection unit detecting a muffling effect by the control sound; An active noise control device comprising: an adaptive control unit that drives the control sound source based on the detection values of the noise detection unit and the noise reduction effect detection unit so that the detection value of the noise reduction effect detection unit is minimized. The detecting means and the silencing effect detecting means are the same kind of detecting means, and each detecting means is used singly or plurally in the cabin.

[0005]

Next, an embodiment of the present invention will be described. FIG. 1 is an overall side view showing a tractor equipped with a cabin of the present invention, FIG. 2 is a block diagram showing a configuration of a muffler, FIG. 3 is a side view showing a first embodiment of an arrangement of the muffler, and FIG. FIG. 5 is a front view of a dashboard showing the arrangement of the silencer, FIG. 5 is a side view showing a second embodiment of the arrangement of the silencer, and FIG. 6 is a side view showing a third embodiment of the arrangement of the silencer. 7 is a side view showing a fourth embodiment of the arrangement of the silencer, FIG. 8 is a side view showing a fifth embodiment of the arrangement of the silencer, and FIG. 9 is a sixth embodiment of the arrangement of the silencer. FIG. 10 is a side view showing a seventh embodiment of the arrangement of the muffler, FIG. 11 is a side view showing the eighth embodiment of the arrangement of the muffler, and FIG. 12 is a ninth embodiment of the arrangement of the muffler. FIG. 13 is a side view showing the tenth embodiment of the arrangement of the muffler.

First, the overall configuration of a tractor equipped with a cabin according to the present invention will be described with reference to FIG. A hood 4 is disposed at the front of the machine which suspends the front wheel 2 and the rear wheel 3 at the front and rear, and an engine 5 is built in the hood 4.
A steering handle 6 is provided behind the hood 4, and a seat 7 is provided behind the steering handle 6. The steering handle 6 and the seat 7 are
Covered by cabin 8. A front window and a rear window (not shown) are provided on the front and rear surfaces of the cabin 8, and a door window 9 is formed on a side portion of the cabin 8, and a side window 10 is provided behind the door window 9. Is formed. The windshield, rear glass, door window 9 and side window 10 are supported by a metal frame. Also,
The bottom surface of the roof 11 of the cabin 8 is made of a material such as resin and has a sound absorbing material. The steps of the cabin 8 are made of sheet metal or the like. The steering wheel 6 is disposed above a dashboard 21 disposed in the cabin 8.
Is constituted by a member made of resin or the like. At the rear of the dashboard 21, a seat 7 with a cushion is provided. A speed change lever, an accelerator lever, and a brake lever for traveling the work vehicle are provided on the side of the seat 7.

A clutch housing 13 is connected to the rear of the engine 5, and a transmission case 14 is connected to the rear of the clutch housing 13.
To be driven. Further, the driving force of the engine 5 is transmitted to a power take-off shaft 15 protruding from the rear end of the transmission case 14 to drive the power take-out shaft (hereinafter, referred to as a PTO shaft) 15, and a work machine mounting device at the rear end of the machine body. It is configured to drive a work machine connected to the work equipment 16.

Next, a control configuration of the active silencer will be described. In FIG. 2, the active silencer includes a reference sensor 31 serving as a noise detecting unit and a monitor microphone 33 serving as a muffling effect detecting unit.
2. It comprises a speaker 34 for outputting a noise canceling sound constituted by the controller 32.

The noise detected by the reference sensor 31 and the sound wave detected by the monitor microphone 33 are input to the controller 32 as electric signals. In the controller 32, the electric signals input from the reference sensor 31 and the monitor microphone 33 are converted into digital signals, and various processes of calculation and correction are performed as digital signals. The digital signal subjected to the processing is converted into an analog signal by the controller 32 and then output from the speaker 34 as a noise canceling sound.

Next, the configuration of the cabin 8 will be described. As shown in FIGS. 3 and 4, in the cabin 8, a dashboard 21 made of a resin material is disposed at a front portion inside the cabin 8, and a steering handle 6 is disposed at an upper portion of the dashboard 21. Has been established. A clutch pedal 22 is provided on the left side of the dashboard 21 on the left side, and brake pedals 22a and 22b are provided on the right side. The clutch pedal 2
2 is connected to the above-described clutch housing 13 via a link mechanism.
4 is configured to be controllable. The brake pedals 22a and 22b are connected to the transmission case 14 via a link mechanism so as to brake the rear wheels 3.3.

Next, a schematic structure of the muffler when applied to the cabin 8 having the above structure will be described with reference to FIG. The reference sensor 31 only needs to be able to detect the pressure fluctuation of the air in the cabin 8, and a microphone or the like can be used. In addition, instead of the reference sensor 31, a later-described reference sensor 41 for detecting vibration or a sensor for detecting noise by other means may be used. In this case, the reference sensor 31 for detecting pressure fluctuation of air is used. Is assumed. The reference sensor 31 is connected to a controller 32 disposed inside the machine body, and is configured to be able to input noise detected by the reference sensor 31 to the controller 32.

On the other hand, a monitor microphone 33 is provided on the roof 11 constituting the upper part of the cabin 8, and the monitor microphone 33 is provided in a position where the operator is seated on the seat 7. Is configured to be located above the head. Thereby, the monitor microphone 33
, So that noise near the operator can be detected. The monitor microphone 33 is connected to the controller 32, and is configured to be able to input a detection value detected by the monitor microphone 33 to the controller 32.

Behind the roof 11 of the cabin 8,
A mute speaker 34 is provided.
4, a sound for reducing the noise can be output. Since the speaker 34 is disposed on the roof 11 as described above, the speaker 34 is
The output sound wave can be prevented from wrapping around the rear of the speaker 34, the output characteristics of the low sound of the speaker 34 can be improved, and the distortion of the output sound wave can be reduced. The speaker 34 is connected to the controller 32, and the detected value detected by the reference sensor 31 and the monitor microphone 33 is transmitted to the controller 3.
2, the sound for reducing the noise in the cabin 8 is output from the speaker 34. A single speaker or a plurality of speakers 34 can be provided as necessary, and the speaker 34 is configured by combining a small-diameter speaker having a high-frequency output characteristic and a large-diameter speaker having an excellent low-frequency characteristic. It is also possible. This makes it possible to eliminate the distortion of the output by the speaker 34.

The schematic configuration of the active silencer when applied to the cabin 8 has been described above. Next, an embodiment relating to the arrangement position of the reference sensor 31 in the cabin 8 will be described with reference to FIGS. When the reference sensor 31 is disposed in the cabin 8 as described above, it is necessary to dispose the reference sensor 31 close to a portion where the pressure fluctuation of air, which is a source of noise, is large. It is detectable and is effective in obtaining a noise-reducing effect with a small number of reference sensors 31 with high accuracy. For example, in the first embodiment shown in FIGS. 3 and 4, the reference sensor 31 is disposed near the dashboard 21. The dashboard 21 is mainly made of resin as described above, and is a portion that is weak in strength and easily oscillates among members constituting the cabin 8, that is, a portion that easily generates pressure fluctuation of air. At the front end of the cabin 8 and close to the hood, engine vibrations are easily transmitted. Therefore, it is a radiation site of the main noise propagating in the cabin. Therefore, by disposing the reference sensor 31 in the vicinity of the dashboard 21, it is possible to detect the sound radiated from the main sound radiating portion in the cabin 8, and it is possible to expect an effective silencing effect.

Next, a description will be given of a second embodiment shown in FIG. FIG.
, The reference sensor 31 is connected to the clutch pedal 22 at the lower part of the dashboard 21 at the front of the cabin 8.
Alternatively, it is installed near the arrangement position of the brake pedals 22a and 22b. This part is the clutch pedal 2
2. In order to allow the brake pedals 22a and 22b to rotate, there are openings in the dashboard 21, and in the vicinity thereof, these pedals are connected to the clutch housing 13 and the outside of the cabin 8 via a link mechanism. There is an opening communicating with the outside of the cabin 8 for connection with the transmission case 14. Therefore, noise enters the cabin through these openings. Thus, by disposing the reference sensor 31 in the vicinity of the noise intrusion path in this way, it is possible to detect noise entering from outside the cabin 8 and to expect an effective noise reduction effect.

Next, a third embodiment shown in FIG. 6 will be described. In FIG. 6, levers for operating a traveling gear or a mounted work machine are arranged on the side of the seat 7 in the cabin 8, and most of the levers are connected to the cabin 8 via a link mechanism. Outer mission case 14
Etc. are connected. An opening serving as a guide groove for these levers is provided on the side of the seat 7 of the cabin 8, and noise outside the cabin 8 enters through this opening. Therefore, by disposing the reference sensor 31 near the opening for the levers on the side of the seat 7, noise entering the cabin 8 can be detected.
An effective silencing effect can be expected.

Next, fourth and fifth embodiments shown in FIGS. 7 and 8 will be described. The cabin 8 is configured to be supported by the fuselage via a support point, for example, on a floor portion thereof. Since this support point vibrates in accordance with the vibration of the airframe, vibration propagation sound enters the cabin 8 via the support point. Therefore, a reference sensor 31 is provided at or near the cabin support point of the cabin 8, and the vibration propagation sound at the support point can be effectively detected, and an improvement in the noise reduction effect can be expected. In the case of the fourth embodiment shown in FIG.
Assuming that the support points are arranged on the floor of the cabin 8, the reference sensor 31 is arranged near the floor. On the other hand, in the case of the fifth embodiment shown in FIG. 8, it is assumed that the support points are arranged at the rear part (the rear part of the fender) of the cabin 8, and the reference sensor 31 is arranged at the rear part of the cabin 8. -ing

Next, in the case where the reference sensor 41 capable of detecting the vibration of the constituent members of the cabin 8 is used as the reference sensor of the present invention, an embodiment of the arrangement of the reference sensor 41 will be described with reference to FIGS. explain. The reference sensor 41 detects the vibration of the component itself, and therefore can detect the vibration propagation sound that is a source of noise in the cabin. As the disposition position of the reference sensor 41, first, as in the sixth embodiment shown in FIG. 9, the same as in the first embodiment shown in FIGS. In addition, it is conceivable to dispose it near the dashboard 21. As described in the first embodiment, the dashboard 21 is a weak member (made of resin or the like) among the constituent members in the cabin 8, and the vibration generated outside the cabin 8 is easily propagated. In the cabin 8, sound is emitted by the vibration of the dashboard 21, which is a main noise source. So, dashboard 21
A reference sensor 41 is arranged near the cabin 8
It detects vibrations of the dashboard 21 which is a main noise source in the interior of the vehicle to improve the noise reduction effect.

The above-mentioned cabin support point can be considered as another site where vibration occurs in the cabin. That is, similarly to the fourth and fifth embodiments shown in FIGS. 7 and 8, in order to detect that the support point vibrates with the vibration generated outside the cabin 8, FIGS. In the seventh and eighth embodiments, the reference sensor 41 is provided at the floor of the cabin 8 having the cabin support point and at the rear of the cabin 8.

Next, a ninth embodiment in which noise in the cabin 8 is detected by a combination of a reference sensor 31 which is a sensor for detecting a fluctuation in atmospheric pressure and a reference sensor 41 for detecting vibration of components of the cabin 8 will be described. FIG.
2 will be described. In the present embodiment, a reference sensor 31 is provided near the dashboard 21 in order to detect a pressure change due to a sound radiated from the dashboard 21, while a support point of the cabin 8 (a floor portion in the present embodiment). Is provided with a reference sensor 41 for detecting vibration, so that noise entering from each part can be detected by each reference sensor. In addition to the present embodiment, as for the combination of sensors and the combination of arrangement locations, the respective embodiments of the first to eighth embodiments can be appropriately selected and variously combined. An effective silencing effect can be obtained according to the sound source information.

Next, a tenth embodiment shown in FIG. 13 will be described. This is a case in which a reference sensor 31 that detects atmospheric pressure fluctuation is used as a reference sensor, and is constituted by the same type of monitor microphone 33 that is disposed on the roof 11 of the cabin 8. conventionally,
Since the monitor microphone was inside the cabin while the reference sensor was placed near the engine, the noise level at the place where each member was placed was different, but in the present invention, the reference sensor was placed inside the cabin 8. Therefore, the noise level is substantially the same as the monitor microphone 33. Therefore, if the microphone having the same sensitivity used for the monitor microphone 33 is used as the reference sensor 31, both can be amplified in the same sound pressure range, and the characteristics of the detection means are the same. The adjustment is easy, and the noise reduction effect can be improved. Although FIG. 13 shows an embodiment arranged near the dashboard 21, the reference sensor 31 having the same sensitivity as that of the monitor microphone 33 is used, for example, in the second to fifth embodiments shown in FIGS. It may be arranged at a location as shown in FIG.

[0022]

As described above, the present invention has the following advantages. That is, a control sound source capable of generating a control sound, a noise detection means for detecting the noise, and a muffling effect due to the control sound are detected in a cabin attached to an airframe having a noise source. An active type comprising: a silencing effect detection unit; and an adaptive control unit that drives the control sound source based on the detection values of the noise detection unit and the silencing effect detection unit so that the detection value of the silencing effect detection unit is minimized. In the noise control device, since one or more sensors for detecting pressure are installed in the cabin as the noise detecting means, not only the noise in the cabin due to the engine noise but also the noise generated due to the strength and shape of the cabin. Can be detected. Noise generated from the mission of the work vehicle and noise generated by vibration of the mission can be detected and silenced. Further, it is possible to detect and mute noise generated by the vibration characteristics of the entire cabin, noise generated by the difference in the strength of members constituting the cabin, or noise generated by the strength characteristics. In addition, noise caused by vibration characteristics and sound field characteristics caused by the shape of the cabin itself can be detected and can be silenced. The noise caused by the sound insulation characteristics of the resin member such as glass or dashboard which is a constituent member of the cabin can be silenced.

According to a second aspect of the present invention, a control sound source capable of generating a control sound, a noise detecting means for detecting the noise, and a noise reduction effect by the control sound are provided in a cabin attached to a body having a noise source. Based on the silencing effect detecting means to be detected, based on the detection values of the noise detecting means and the silencing effect detecting means,
An active noise control device comprising: an adaptive control means for driving the control sound source so that a detection value of the noise reduction effect detection means is minimized. In the active noise control apparatus, vibration is detected as a noise detection means by a member constituting the cabin. Since one or a plurality of sensors are installed, not only noise due to engine noise but also noise generated due to the strength and shape of the cabin can be detected. Noise generated from the mission of the work vehicle and noise generated by the vibration of the mission can be detected by vibration transmitted to the cabin, and noise generated by the vibration can be muted. Further, the noise generated by the vibration characteristics of the entire cabin, the difference in the strength of the members forming the cabin or the strength characteristics of the members forming the cabin vibrates, and the generated noise can be detected at the time of the vibration. In addition, the effect of silencing noise generated by the vibration can be improved. Further, noise caused by vibration characteristics and sound field characteristics caused by the material and shape of the cabin itself can be detected by the vibration of the cabin, and the noise can be silenced. The noise caused by the sound insulation characteristics and vibration absorption characteristics of resin members such as glass and dashboard, which are components of the cabin, can be reduced.

According to a third aspect of the present invention, a control sound source capable of generating a control sound, a noise detecting means for detecting the noise, and a muffling effect by the control sound are detected in a cabin attached to a body having a noise source. And an adaptive control means for driving the control sound source based on the detection values of the noise detection means and the noise reduction effect detection means so as to minimize the detection value of the noise reduction effect detection means. In the type noise control device, a plurality of different types of sensors are installed in the cabin as the noise detecting means, so that a plurality of sensors can be combined to detect noise and vibrations that generate noise, and the noise is detected by the plurality of sensors. A noise canceling sound having a high noise canceling effect can be configured by the information on the noise.

According to a fourth aspect of the present invention, a control sound source capable of generating a control sound, a noise detection means for detecting the noise, and a noise reduction effect by the control sound are provided in a cabin attached to a body having a noise source. A muffling effect detecting means for detecting, and an adaptive control means for driving the control sound source based on the detection values of the noise detecting means and the muffling effect detecting means so as to minimize the detection value of the muffling effect detecting means. In the active noise control device, since the noise detecting means and the muffling effect detecting means are the same kind of detecting means, and each of the detecting means is used singly or plurally in the cabin, input is made by the means for detecting the muffling effect. In a controller in which a signal is connected to the means for detecting the muffling effect, the signal can be amplified in the same sound pressure range, and the muffling effect can be improved. In addition, since noise detection means is installed in the cabin,
Since the muffling effect can be detected in the sound pressure range for detecting the noise generated in the cabin without lowering the detection accuracy, the noise detection means and the muffling effect detection means provided in the cabin are the same. It can be configured by components. For this reason, it is possible to reduce the cost of the components of the noise detection means and the noise reduction effect detection means, and it is possible to reduce the manufacturing cost. In addition, since the noise detection means and the noise reduction effect detection means are configured by detection means having the same characteristics,
Adjustment of the muffling effect detecting means with respect to the noise detecting means or adjustment of the noise detecting means with respect to the muffling effect detecting means is easy, and adjustment of the muffling device can be easily performed.

[Brief description of the drawings]

FIG. 1 is an overall side view showing a tractor equipped with a cabin of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a muffling device.

FIG. 3 is a side view showing a first embodiment of the arrangement of the muffler.

FIG. 4 is a front view of a dashboard showing an arrangement configuration of the muffler.

FIG. 5 is a side view showing a second embodiment of the arrangement of the muffler.

FIG. 6 is a side view showing a third embodiment of the arrangement of the muffler.

FIG. 7 is a side view showing a fourth embodiment of the arrangement of the muffler.

FIG. 8 is a side view showing a fifth embodiment of the arrangement of the muffler.

FIG. 9 is a side view showing a sixth embodiment of the arrangement of the muffler.

FIG. 10 is a side view showing a seventh embodiment of the arrangement of the muffler.

FIG. 11 is a side view showing an eighth embodiment of the arrangement of the muffler.

FIG. 12 is a side view showing a ninth embodiment of the arrangement of the muffler.

FIG. 13 is a side view showing a tenth embodiment of the arrangement of the muffler.

[Explanation of symbols]

 8 Cabin 11 Cabin Roof 21 Dashboard 22 Clutch Pedal 31 Reference Sensor (Pressure Fluctuation Detection Type) 32 Controller 33 Monitor Microphone 34 Speaker 41 Reference Sensor (Vibration Detection Type)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shigeki Tada 1-32 Chayacho, Kita-ku, Osaka, Osaka Inside Yanmar Diesel Co., Ltd. (72) Eiji Koizumi 1-32 Chayacho, Kita-ku, Osaka, Osaka F-term (reference) in Yanmar Diesel Co., Ltd. 3D020 BA01 BB05 BB07 BC01 BD05 BE04 5D061 FF02

Claims (4)

[Claims] 1. A control sound source capable of generating a control sound in a cabin attached to an airframe having a noise source, a noise detection unit for detecting the noise, and a noise reduction effect detection unit for detecting a noise reduction effect by the control sound. And an adaptive control means for driving the control sound source based on the detection values of the noise detection means and the silencing effect detection means so that the detection value of the silencing effect detection means is minimized. A muffler, wherein one or more sensors for detecting pressure are provided as the noise detecting means in the cabin. 2. A control sound source capable of generating a control sound in a cabin attached to an airframe having a noise source, a noise detection unit for detecting the noise, and a noise reduction effect detection unit for detecting a noise reduction effect by the control sound. And an adaptive control means for driving the control sound source based on the detection values of the noise detection means and the silencing effect detection means so that the detection value of the silencing effect detection means is minimized. A noise eliminator, wherein one or a plurality of sensors for detecting vibrations are provided as the noise detecting means on a member constituting the cabin. 3. A control sound source capable of generating a control sound in a cabin attached to an airframe having a noise source, a noise detection means for detecting the noise, and a noise reduction effect detection means for detecting a noise reduction effect by the control sound. An active noise control device comprising: an adaptive control unit that drives the control sound source so that the detection value of the noise reduction effect detection unit is minimized based on the detection values of the noise detection unit and the noise reduction effect detection unit. A silencer comprising a plurality of sensors of different types installed as noise detection means in the cabin. 4. A control sound source capable of generating a control sound in a cabin attached to an airframe having a noise source, a noise detection means for detecting the noise, and a noise reduction effect detection means for detecting a noise reduction effect by the control sound. And an adaptive control means for driving the control sound source based on the detection values of the noise detection means and the silencing effect detection means so that the detection value of the silencing effect detection means is minimized. A noise eliminator, wherein the noise detector and the noise elimination effect detector are the same type of detector, and one or a plurality of each detector is used in a cabin.