JPH06351092A - Microphone for detecting external noise - Google Patents

Abstract

PURPOSE:To provide an external noise detecting use sensor microphone to be used for a silencer for a building by considering the acoustic transmission characteristic of the building such as housing. CONSTITUTION:In the sensor microphone to be used for a silencer for actively silencing external noise by radiating an additional sound to become a reverse phase to the waveform component of the external noise for the external noise intruding in a dwelling space to the external noise so as to output an external noise signal by detecting the external noise on the outer wall of the building, an acoustic filter 15 for cutting off the high frequency component of the external noise is provided with in front of a sensor microphone body 1A and the body 1A is stored in a cabinet 13 having durability on an aperture on its front part and the outer periphery of the cabinet 13 is coated with an elastic supporting member having a vibration preventing characteristic.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microphone for detecting external noise, and more particularly, it is used in a muffler for actively muffling external noise that invades a living space. The present invention relates to a microphone that detects noise and outputs an external noise signal.

[0002]

2. Description of the Related Art As a muffling device that actively muffles external noise propagating in a duct (wind passage) provided in a vehicle or the like,
For example, JP-A-1-236800 and JP-A-2-7
There are those described in Japanese Patent No. 2395. These silencers are provided on the upstream side of the duct, and are provided along the duct with a sensor microphone that detects external noise.
Based on the output signal of the sub-duct whose downstream end merges with the duct, the speaker provided at the upstream end of the sub-duct, and the output signal of the above-mentioned microphone, the noise of the same amplitude in the opposite phase to the external noise in the duct is eliminated. And a control circuit for outputting sound waves from the speaker. As the sensor microphone, as described in Japanese Utility Model Laid-Open No. 4-119316, there is a sensor microphone whose front surface is covered with a protective cover to enhance environmental resistance.

[0003]

By the way, although the above-mentioned patent publication describes the basic principle and basic configuration of the silencer, the silencer is applied to an actual building such as a house. No specific shape or workability of the device at that time is described. Further, the above-mentioned utility model publication does not describe a specific material for obtaining a suitable protective cover, let alone a characteristic in consideration of characteristics of a building such as a house. Therefore, when installing this muffling device to a building such as a house, the house must be modified, and the installation is troublesome, and the sensor microphone also takes into consideration the sound transmission characteristics of the building such as a house. However, there is a problem that it is not practical. This invention
Against this background, the purpose of the invention is to provide a sensor microphone (a microphone for detecting external noise) that takes into account the sound transmission characteristics of a building such as a house, which was made as part of the provision of a silencer for buildings. I am trying.

[0004]

In order to solve the above-mentioned problems, the invention according to claim 1 provides an additional noise having an opposite phase to the waveform component of the external noise with respect to the external noise invading the living space. A microphone used for a silencer that radiates and actively silences the external noise, detects the external noise on the outer wall of the building or in the vicinity thereof, and outputs the external noise signal, which is the front surface of the microphone body. In addition, a high frequency component sound insulating member for insulating the high frequency component of the external noise is provided.

According to a second aspect of the present invention, the main body of the microphone is housed in a heavy metal housing having a front opening, and the outer peripheral surface of the housing is covered with a vibration isolating member. It has a feature.

The invention according to claim 3 is characterized in that the high frequency component sound insulation member is made of a waterproof material.

Furthermore, the invention according to claim 4 is characterized in that the sound transmission characteristics of the high frequency component sound insulation member are set to be substantially equal to the sound transmission characteristics of the outer wall material constituting the building.

[0008]

OPERATION As a premise, the external noise that intrudes through the outer wall of the building absorbs its high frequency component and is attenuated by the outer wall of the building. Therefore, the external noise that intrudes inside the building consists mainly of low frequency components. There is. Therefore, the target of noise reduction inside the building is mainly low-frequency components of external noise. According to the microphone of the present invention, the high-frequency component of the external noise is shielded by the high-frequency component sound insulation member provided on the front surface of the microphone body, so that the low-frequency component of the external noise, which is the main target of noise reduction, is accurately detected. be able to. As an additional effect, it is possible to omit a low-pass filter conventionally required in a signal processing unit, and it is possible to prevent a delay in signal processing by the low-pass filter. As the high frequency component sound insulation member, a urethane sheet, a silicone rubber sheet or the like is suitable. Further, according to the configurations of claims 2 to 4, the characteristics such as the outer wall of the building and the environment in which the outer wall is placed can be further adapted. Therefore, the microphone of the present invention is suitable for use as a silencer for homes.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a vertical cross-sectional view showing the mechanical structure of a microphone for detecting external noise (hereinafter referred to as a sensor microphone in the section of the embodiments) which is an embodiment of the present invention, and FIG. 2 is a line AA in FIG. FIG. In these drawings, reference numeral 1 denotes the same sensor microphone, and this sensor microphone 1 comes from the outside, for example, aircraft noise,
From a cylindrical acoustic sensor unit 11 that detects the level of vehicle noise such as buses and railway noise and converts it into an external noise signal, and an amplification unit 12 that amplifies the external noise signal output from the acoustic sensor unit 11. The sensor microphone body 1A is configured.

The sensor microphone body 1A is made of a heavy metal made of iron or lead in a cylindrical housing 13 with one end open.
The front surface of the acoustic sensor unit 11 is housed with the common axis center with the front side facing the outside through the open end. Here, in order not to directly contact the sensor microphone main body 1A with the housing 13,
A resin mold 14 is interposed between the two.

An acoustic filter 15 is provided at the open end of the housing 13 for insulating high frequency components of external noise. The acoustic filter 15 is made of a soft film,
Specifically, it is made of urethane sheet or silicone rubber. The material of these acoustic filters 15 is similar to the sound transmission (loss) characteristics of the outer wall material of the building, absorbs high-frequency components of external noise, and is also excellent in waterproofness and weather resistance.

The casing 13 has an E-shaped outer peripheral portion excluding the open end.
PDM (ethylene-propylene-diene-terpolymer)
It is the elastic support member 16 that is thickly covered with the elastic support member 16 such as foam and that is actually brought into contact with the outer wall or the like of the building and is tightly connected to the outer wall or the like, whereby the solid propagating sound is insulated. It is done like this. Reference numeral 17 indicates an acoustic filter retainer, and reference numeral 18 indicates electric wires such as a power supply line and an output line.

The sensor microphone 1 having the above-mentioned structure is used as an external noise detecting means of a silencer for silencing external noise that enters the building, and as shown in FIG.
Attached to.

FIG. 4 shows an electrical construction of a muffler 3 for building installation which is applied to this example. This muffler 3 includes the sensor microphone 1, the control unit 4, an additional sound source speaker 5, and an error. The microphone 6 is generally configured. The control unit 4 includes a control unit 41 for controlling each part of the apparatus, an A / D converter 42 for converting an analog acoustic signal into a digital signal, an external noise signal supplied from the sensor microphone 1 and a residual supplied from the error microphone 6. Electricity is generated from a signal processing unit 43 that generates digital additional sound data for canceling external noise based on the noise and supplies the additional sound source speaker 5 and a D / A converter 44 that converts the digital signal into an analog acoustic signal. And is attached to the wall surface in the room, as shown in FIG. Based on the additional sound data supplied from the control unit 4, the additional sound source speaker 5 emits an additional sound having a phase opposite to that of the external noise, and silences the external noise that has entered the room. Further, the error microphone 6 is connected to the additional sound source speaker 5
The residual noise level is provided at a position where the noise should be silenced in the room, which detects the residual noise level, converts the residual noise signal into a residual noise signal, and sends the signal to the control unit 4.

In the above structure, the high frequency component of the external noise is cut by the acoustic filter 15 provided on the front surface of the sensor microphone body 1A. Therefore, the low frequency component of the external noise is mainly output from the sensor microphone 1 and supplied to the control unit 4. On the other hand, the external noise that enters through the outer wall of the building absorbs its high-frequency components and is attenuated by the outer wall of the building, so it enters the inside of the building,
External noise to be silenced mainly consists of low frequency components.

Therefore, according to the above configuration, the excess high-frequency component is removed or reduced and output from the sensor microphone 1, so that the detection performance that is truly required can be improved. In addition, the solid-borne noise that is about to enter from the outer wall 21 is cut by the elastic support member 16. Moreover, the acoustic sensor unit 11 has a proof housing 13
Since it is stored in, it is possible to apply the silencer to a building. As an additional effect, it becomes possible to omit the low-pass filter conventionally required in the control unit 4, and it is possible to prevent a delay in signal processing by the low-pass filter. Further, since the acoustic filter 15 is made of a waterproof material, it is possible to avoid damage or damage even in the rain.

Although the embodiment of the present invention has been described in detail above with reference to the drawings, the specific structure is not limited to this embodiment, and the design change and the like without departing from the scope of the invention. Even this is included in this invention. For example, the acoustic filter is not limited to the urethane sheet or the rubber sheet, but may be a polypropylene sheet or an acrylic sheet. Also,
These may be laminated. If this acoustic filter is applied to an error microphone as well, high-frequency components generated indoors can be removed, and further improvement in sound deadening performance is expected.

[0018]

As described above, according to the configuration of the present invention, the high frequency component of the external noise is shielded by the high frequency component sound insulation member provided on the front surface of the microphone body, which is the main cause of noise elimination in the building. It is possible to accurately detect the low-frequency component of the target external noise. As an additional effect, it is possible to omit a low-pass filter conventionally required in a signal processing unit, and it is possible to prevent a delay in signal processing by the low-pass filter. Further, according to the configuration of the second aspect, it is possible to cut off solid-borne noise that is about to enter from the outer wall. In addition, the microphone body is housed in a housing that has a bearing capacity. Therefore, it is suitable for use as a silencer for homes.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a mechanical configuration of a microphone for detecting external noise, which is an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the microphone taken along the line AA of FIG.

FIG. 3 is a diagram showing a state in which the microphone is attached to an outer wall of a building.

FIG. 4 is a block diagram showing an electrical configuration of a silencer applied to the same example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 sensor microphone (microphone for external noise detection) 1A sensor microphone main body (microphone main body) 11 acoustic sensor section 13 housing 14 resin mold 15 acoustic filter (high frequency component sound insulation member) 16 elastic support member (vibration isolation member) 2 building 21 Outer wall 3 silencer

Claims (4)

[Claims] 1. A building used for a muffling device which radiates an additional sound having a phase opposite to a waveform component of the external noise to the external noise invading the living space to actively muffle the external noise. Is a microphone for detecting the external noise and outputting the external noise signal on the outer wall or in the vicinity thereof, wherein a high frequency component sound insulating member for insulating the high frequency component of the external noise is provided on the front surface of the microphone body. Microphone for external noise detection. 2. A microphone for external noise detection, wherein the main body of the microphone is housed in a case made of heavy metal having a front opening, and the outer peripheral surface of the case is covered with a vibration isolating member. 3. The microphone for external noise detection according to claim 1, wherein the high frequency component sound insulation member is made of a waterproof material. 4. A microphone for external noise detection, wherein a sound transmission characteristic of the high frequency component sound insulation member is set to be substantially equal to a sound transmission characteristic of an outer wall material forming the building.