Audio calibration device

Abstract

To provide an acoustic calibrator capable of applying the same sound pressure to a microphone and a sound pressure measurement sensor while facilitating the attachment of the sound pressure measurement sensor and a sounder.SOLUTION: An acoustic calibrator includes: a coupler body 24 having an internal space 22 with which a socket 21 into which a microphone M is inserted communicates; a coupler flange 23 that is coupled to the coupler body 24 from an opposite side of the socket 21 and that has a sensor attachment port 31 communicating with the internal space 22; a sound pressure measurement sensor 16 that measures a sound pressure in the internal space 22; and a sounder 62 that outputs sound into the internal space 22. The coupler body 24 includes a tip cylindrical member 41 in which the socket 21 is formed, and a base end cylindrical member 43 to which the coupler flange 23 is coupled. The coupler body 24 includes a groove-shaped sound guide path 65 that communicates with the internal space 22 to open to a connected surface between the tip cylindrical member 41 and the base end cylindrical member 43, and a sounding chamber 61 which communicates with the sound guide path 65 and in which the sounder 62 is arranged.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an acoustic calibrator. [Background technology]

[0002] Generally, an acoustic calibrator used to calibrate a microphone comprises a coupler, a sound pressure measurement sensor, a sound generator, and a control device. The coupler has an internal space and a socket that communicates with the internal space and into which the microphone to be calibrated is inserted. The sound pressure measurement sensor measures the sound pressure in the internal space of the coupler. The sound generator outputs sound into the internal space of the coupler. The control device controls the output of the sound generator so that the measurement value of the sound pressure measurement sensor matches the calibration reference value. The microphone to be calibrated is then calibrated so that the measurement value when inserted into the socket of the coupler matches the calibration reference value.

[0003] As such an acoustic calibrator, Patent Document 1 discloses an acoustic calibrator in which the internal space of the coupler is divided by a sound-generating body into a front chamber that communicates with the socket and a back chamber that is the measurement target of the sound pressure measurement sensor, so that the attachment of the sound pressure measurement sensor to the coupler is easy. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2017-175576 Summary of the Invention [Problem to be solved by the invention]

[0005] In the sound calibrator described in Patent Document 1, it is preferable that the volume of the front chamber and the volume of the back chamber are the same. However, because the microphone to be calibrated also has a front chamber volume, the volume of the front chamber of the sound calibrator varies depending on the microphone to be calibrated. This can result in a difference in volume between the front chamber and the back chamber of the sound calibrator. The greater this volume difference, the greater the difference between the sound pressure applied to the microphone and the sound pressure applied to the sound pressure measurement sensor. Therefore, there has been a demand for technology that makes it easy to install the sound pressure measurement sensor while making the sound pressure applied to the microphone and the sound pressure measurement sensor the same. [Means for solving the problem]

[0006] An acoustic calibrator that solves the above problem includes a cylindrical coupler body having a socket into which a microphone is inserted and an internal space communicating with the socket, a coupler flange connected to the coupler body from the opposite side of the socket and having a sensor mounting port communicating with the internal space, a sound pressure measurement sensor that measures the sound pressure in the internal space, the sound pressure measurement sensor having a sensing part disposed in the internal space through the sensor mounting port, and a sound generator that outputs sound into the internal space. The coupler body includes a distal tubular member having the socket formed therein and a proximal tubular member to which the coupler flange is connected, and further includes a groove-shaped sound guide path that communicates with the internal space and opens at a connecting surface between the distal tubular member and the proximal tubular member, and a sound generator that communicates with the sound guide path and in which the sound generator is disposed. The sound generator outputs sound into the internal space through the sound guide path.

[0007] According to the above configuration, the sound pressure measurement sensor can be attached to the coupler flange that constitutes the coupler, making it easy to attach the sound pressure measurement sensor. Furthermore, since the output space of the sound generator and the measurement space of the sound pressure measurement sensor and microphone are shared within the internal space of the coupler body, the sound pressure applied to the microphone and the sound pressure applied to the sound pressure measurement sensor can be made the same.

[0008] In the sound calibrator having the above configuration, it is preferable that the sound guide path has a portion that extends in a circumferential direction of the coupler body. By providing a sound guide, Helmholtz resonance can be generated in the internal space of the coupler body by the inductance component of the sound guide and the capacitance component of the internal space of the coupler body. The resonant frequency of the Helmholtz resonance can be adjusted by the cross-sectional area and length of the sound guide. With the above configuration, the sound guide has a portion that extends circumferentially around the coupler body, which allows for a high degree of freedom in the length of the sound guide, and therefore the sound guide can be designed to achieve a desired resonant frequency. As a result, the electrical input signal required to drive the sound generator can be reduced.

[0009] In addition, the resistance component of the sound guide and the capacitance component of the internal space of the coupler body form an RC low-pass filter characteristic.The high degree of freedom in the length of the sound guide also makes it possible to effectively suppress high-frequency distortion components generated by the sound generator.

[0010] In the sound calibrator having the above configuration, it is preferable that the sound guide path and the sound-producing chamber are formed in the base-end cylindrical member. With the above configuration, the distal end tube member can be made smaller, and therefore the coupler can be made smaller, compared to when the sound guide and sound chamber are formed in the distal end tube member. Furthermore, for example, when the sound guide is formed in the distal end tube member and the sound chamber is formed in the proximal end tube member, there is a risk that the sound guide and the sound chamber will be separated due to misalignment of the distal end tube member and the proximal end tube member when they are connected. In this regard, with the above configuration, the sound guide and the sound chamber are directly connected, so they will not be separated.

[0011] In the sound calibrator having the above configuration, the coupler body preferably includes a sealant disposed outside the sound guide path to seal the gap between the tip tube member and the base tube member.

[0012] According to the above configuration, the gap between the distal end tubular member and the proximal end tubular member is sealed with a sealing material, preventing sound leakage through the gap, thereby allowing the sound output by the sound generator to be efficiently transmitted to the internal space of the coupler body. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a perspective view showing a schematic configuration of an embodiment of a sound calibrator. [Figure 2] FIG. 2 is a diagram schematically illustrating a cross-sectional structure of a main part of a coupler. [Figure 3] FIG. [Figure 4] FIG. 2 is a perspective view of the base end tube member as viewed from the tip end surface side. [Figure 5] FIG. 2 is a plan view of the base end cylindrical member as viewed from the base end surface side. [Figure 6] 10 is a graph showing an example of the relationship between frequency and sound pressure level when the resonance frequency is used as the calibration frequency, and the relationship between frequency and gain of high-frequency distortion components in that case. [Figure 7] 10 is a graph showing an example of the relationship between the frequency of a noise component entering the internal space of a coupler and the noise level thereof; [Figure 8] FIG. 1(a) is a diagram showing a vent in Example 1, (b) is a diagram showing a vent in Example 2, and (c) is a diagram showing a vent in Example 3. [Figure 9] FIG. 10 is a diagram showing a vent in a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0014] An embodiment of the sound calibrator will be described with reference to FIGS. As shown in FIG. 1, sound calibrator 10 has housing 11 in a substantially rectangular parallelepiped shape. Housing 11 is formed by connecting a front member 12 having a front wall 12a and a rear member 13 having a rear wall 13a. Housing 11 has a coupler insertion hole 14 in the center of front wall 12a, through which the tip of coupler 20 is inserted from the inside. A socket 21 is formed at the tip of coupler 20, into which microphone M to be calibrated is inserted. In sound calibrator 10, when a predetermined operation is performed with microphone M to be calibrated inserted into socket 21, sound generator 62 (see FIG. 2) is driven, and a sound (calibration signal) of a calibration frequency (e.g., 1 kHz) and a calibration sound pressure (e.g., 114 dB) is output into the internal space of coupler 20. Microphone M is then calibrated so that the sound of the calibration frequency and the calibration sound pressure is measured.

[0015] An electronic board 15 and a coupler 20 are disposed inside the housing 11. The electronic board 15 is disposed along the rear wall 13a of the housing 11. Various electronic devices are electrically connected to the electronic board 15. The electronic board 15 is attached to the rear wall 13a of the housing 11 with standoffs 18 that have screws.

[0016] The coupler 20 is disposed so as to face the electronic board 15 from the front wall 12a side. The coupler 20 has a coupler flange 23 and a coupler body 24. The coupler 20 is attached with a predetermined gap between it and the electronic board 15 by connecting the coupler flange 23 to the standoffs 18 with mounting fasteners 25. The coupler body 24 has a cylindrical shape with a jack 21, into which the microphone M is inserted, formed at its tip. The coupler flange 23 is disposed so as to cover the opening of the coupler body 24 on the opposite side from the jack 21. A spacer 19, which maintains the predetermined gap, is connected to the coupler flange 23 with a spacer fastener 26.

[0017] The coupler flange 23 is composed of a flange main body 27 and a connecting auxiliary plate 28. The flange main body 27 is formed into a rectangular plate shape with a central recess for accommodating the connecting auxiliary plate 28. The connecting auxiliary plate 28 is also formed into a rectangular plate shape. The flange main body 27 and the connecting auxiliary plate 28 are fabricated by machining a metal base material. The flange main body 27 and the connecting auxiliary plate 28 are connected to each corner of the connecting auxiliary plate 28 by flange fastening members 30. The coupler main body 24 is connected to the flange main body 27 via the connecting auxiliary plate 28.

[0018] 2, a sound pressure measurement sensor 16 is attached to the electronic board 15. The sound pressure measurement sensor 16 measures the sound pressure in the internal space 22 of the coupler 20 (the internal space of the coupler body 24). The electronic board 15 also has a control circuit mounted thereon that controls the sound generator 62 based on the detection value of the sound pressure measurement sensor 16 so that sound of the calibrated frequency and calibrated sound pressure is output into the internal space 22 of the coupler 20.

[0019] A sensor mounting port 31 penetrating the coupler flange 23 in the thickness direction is formed in the coupler flange 23 in a portion covering the opening of the coupler main body 24. The sensing portion 16A of the sound pressure measurement sensor 16 is inserted into the sensor mounting port 31. By inserting the sensing portion 16A of the sound pressure measurement sensor 16 into the sensor mounting port 31, it becomes possible for the sound pressure measurement sensor 16 to measure the sound pressure in the internal space 22 of the coupler 20. The gap between the outer peripheral surface of the sensing portion 16A and the inner peripheral surface of the sensor mounting port 31 is sealed by a mounting port sealant 32. The mounting port sealant 32 is attached to the coupler flange 23 by connecting the flange main body 27 and the connecting auxiliary plate 28 while being disposed in a sealing recess 33 formed in the flange main body 27.

[0020] The electronic board 15, with the sound pressure measuring sensor 16 attached, is attached to the rear wall 13a of the housing 11 by the standoffs 18. The coupler 20 is positioned so that the sensing portion 16A of the sound pressure measuring sensor 16 is inserted into the sensor attachment opening 31, and then the coupler flange 23 is attached to the standoffs 18 by the attachment fasteners 25. In this way, the coupler 20 is attached to the rear wall 13a of the housing 11 via the standoffs 18. Note that the surface of the coupler flange 23 that abuts against the coupler main body 24 is the flange-side coupling surface 23a to which the coupler main body 24 is coupled.

[0021] (Coupler body) 2 to 8, the coupler body 24 will be described in more detail. Note that, hereinafter, the direction along the central axis 24A of the coupler body 24 will be referred to as the axial direction, the direction perpendicular to the central axis 24A will be referred to as the radial direction, and the direction around the central axis 24A will be referred to as the circumferential direction. Also, the side of the coupler flange 23 in the axial direction will be referred to as the base end side, and the side opposite the coupler flange 23 will be referred to as the tip end side.

[0022] As shown in Figure 2, the coupler body 24 has a distal tube member 41 and a proximal tube member 43. Each of the members 41 and 43 is made by machining a metal base material. The distal tube member 41 is connected to the proximal tube member 43 by a distal fastening member 45. The proximal tube member 43 is connected to the coupler flange 23 by a proximal fastening member 46.

[0023] (Tip tube member) 2 and 3, tip tube member 41 is a member in which insertion port 21 for microphone M is formed. Base end surface 41b of tip tube member 41 is a connecting surface that is connected to base end tube member 43. Tip tube member 41 has a small-diameter tip tube main body 51 and a large-diameter flange portion 52 that are integrally connected.

[0024] The tip of the tip tube body 51 is disposed outside the housing 11 through the coupler insertion hole 14. The outer periphery at the tip of the tip tube body 51 is chamfered. The tip tube body 51 has a receptacle 21 with a circular cross section and a locking portion 53 that locks the microphone M inserted into the receptacle 21. The tip tube body 51 also has a sealing groove 54 that is recessed radially outward from the inner circumferential surface of the receptacle 21, closer to the tip than the locking portion 53. A receptacle sealant 55 is disposed in the sealing groove 54. The receptacle sealant 55 seals the gap between the outer circumferential surface of the microphone M and the inner circumferential surface of the receptacle 21 when the microphone M is inserted into the receptacle 21. Note that in FIG. 3, the receptacle sealant 55 is omitted from the view of the tip tube member 41.

[0025] The flange portion 52 extends radially outward from the base end of the tip tube main body 51. The flange portion 52 has tip connecting holes 56 in which the tip side fastening members 45 are disposed. The tip connecting holes 56 are formed at predetermined intervals in the circumferential direction and penetrate the flange portion 52 in the axial direction. The tip connecting holes 56 have a head accommodating portion in which the heads of the tip side fastening members 45 are accommodated. The flange portion 52 is disposed from the inside of the housing 11 opposite the periphery of the coupler insertion hole 14 in the front wall 12a of the housing 11 so that the opening portion of the tip connecting hole 56 is covered.

[0026] (Base end cylindrical member) 2, the base end tube member 43 is a member disposed between the coupler flange 23 and the tip tube member 41. The base end tube member 43 has an inner diameter that is approximately equal to that of the flange portion 52 of the tip tube member 41, and an outer diameter that is approximately equal to that of the flange portion 52. The tip surface 43a of the base end tube member 43 is a connecting surface that is connected to the tip tube member 41, and the base end surface 43b of the base end tube member 43 is a connecting surface that is connected to the coupler flange 23.

[0027] The base end tubular member 43 has a sound-producing chamber 61. The sound-producing chamber 61 is a space in which a sound-producing body 62 that outputs sound to the internal space 22 of the coupler 20 is disposed. The sound-producing chamber 61 has an opening in the base end face 43b and is a groove-shaped space that extends in the axial direction from the base end face 43b to the tip end face 43a. With the base end tubular member 43 connected to the coupler flange 23, the sound-producing body 62 is disposed in the sound-producing chamber 61 through a main body through-hole 63 of the flange main body 27 and an auxiliary plate through-hole 64 of the auxiliary connection plate 28. After that, the sound-producing body 62 is fixed in position by hardening an adhesive that is poured into the through-holes 63, 64 so as to seal the sound-producing chamber 61.

[0028] The base end tubular member 43 has a sound guide 65. The sound guide 65 is a passage that guides the sound output from the sound generator 62 to the internal space 22 of the coupler 20. The sound guide 65 is made up of a first sound guide portion 66 and a second sound guide portion 67.

[0029] As shown in FIG. 4, the first sound guide 66 is a groove-shaped passage recessed in the tip end surface 43a. The first sound guide 66 extends circumferentially from the connection with the second sound guide 67 around the internal space 22 of the coupler 20, then bends radially inward and opens at the inner circumferential surface of the base end tubular member 43. When the tip end tubular member 41 and the base end tubular member 43 are connected, the opening of the first sound guide 66 facing the tip end surface 43a is closed by the base end surface 41b of the tip end tubular member 41. The second sound guide 67 extends axially from the sound chamber 61 toward the tip end surface 43a. The second sound guide 67 is a through passage that connects the sound chamber 61 and the first sound guide 66. An output port 62a of the sound generator 62 is disposed in the second sound guide 67. A design method for such a sound guide 65 will be described later.

[0030] The base end cylindrical member 43 has an annular groove 71 recessed in the tip surface 43a. The annular groove 71 extends circumferentially radially outward of the sound guide path 65. A sealant 72 is disposed in the annular groove 71. The sealant 72 seals the gap between the base end surface 41b of the tip end cylindrical member 41 and the tip surface 43a of the base end cylindrical member 43. Note that in Figure 4, the sealant 72 is omitted from the illustration of the base end cylindrical member 43.

[0031] The base end tubular member 43 has tip side fastening holes 73. The tip side fastening holes 73 are formed radially outward from the annular groove 71. The tip side fastening holes 73 are formed at predetermined intervals in the circumferential direction so as to communicate with the tip side connecting holes 56. Tip side fastening members 45 are fastened to the tip side fastening holes 73 through the tip side connecting holes 56.

[0032] 2, the base-end tubular member 43 has base-end fastening holes 74. The base-end fastening holes 74 are formed radially outward of the annular groove 71. The base-end fastening holes 74 are formed at predetermined intervals in the circumferential direction. The base-end fastening members 46 are fastened to the base-end fastening holes 74 through main body connecting holes 75 of the flange main body 27 and auxiliary plate connecting holes 76 of the auxiliary connecting plate 28.

[0033] The base end tubular member 43 has a protective grid 81. The protective grid 81 protects the sensing portion 16A of the sound pressure measuring sensor 16 from foreign matter that enters the internal space 22 of the coupler 20 through the insertion port 21, for example.

[0034] The base end cylindrical member 43 has a groove-shaped vent 90. The vent 90 is recessed in the base end surface 43b. The vent 90 opens to the inner and outer circumferential surfaces of the base end cylindrical member 43. The vent 90 is a passage that releases the increased pressure in the internal space 22 of the coupler 20 to the external space when the microphone M is inserted into the socket 21. When the coupler flange 23 and the base end cylindrical member 43 are connected, the opening of the vent 90 facing the base end surface 43b is closed by the flange-side connecting surface 23a of the coupler flange 23.

[0035] As shown in FIG. 5 , the vent 90 has an inner groove 91, an outer groove 92, and a connecting groove 93. The inner groove 91 opens to the inner circumferential surface of the base end tubular member 43. The inner groove 91 extends radially outward from its opening in the inner circumferential surface. The outer groove 92 opens to the outer circumferential surface of the base end tubular member 43. The outer groove 92 extends radially inward from its opening in the outer circumferential surface. The inner groove 91 and the outer groove 92 are formed at different positions in the circumferential direction. The connecting groove 93 connects the outer end of the inner groove 91 and the inner end of the outer groove 92 so as not to interfere with the sound chamber 61. The connecting groove 93 extends circumferentially at a position closer to the base end fastening hole 74 than the inner circumferential surface of the base end tubular member 43. The connecting groove 93 preferably connects the inner groove 91 and the outer groove 92 on the more oblique angle side of the angle formed by the inner groove 91 and the outer groove 92. A method for designing such a vent 90 will be described later.

[0036] (Sound guide design method) In the coupler 20, when the sound generator 62 generates a sound of the calibrated frequency and calibrated sound pressure, high-frequency distortion components are generated due to the mechanical characteristics of the sound generator 62. These high-frequency distortion components are acoustically amplified by the frequency characteristics of the sound generator 62, and may affect the calibrated signal emitted by the sound generator 62.

[0037] Meanwhile, in the coupler 20, Helmholtz resonance occurs due to the inductance component of the sound guide 65 and the capacitance component of the internal space 22 of the coupler 20. The inductance component is expressed by equation (1), the capacitance component by equation (2), and the resonant frequency f of Helmholtz resonance by equation (3). Based on these equations (1) to (3), the length and cross-sectional area of ​​the sound guide 65 are determined so that the resonant frequency f becomes the calibration frequency. In other words, the length and cross-sectional area of ​​the sound guide 65 are determined so that the resonant frequency f becomes the calibration frequency by utilizing acoustic amplification in the coupler 20.

[0038]

number

[0039]

number

[0040]

number

[0041] Furthermore, in the coupler 20, a characteristic equivalent to an RC low-pass filter is formed by the resistance component of the sound guide 65 and the capacitance component of the internal space 22 of the coupler 20. The acoustic resistance R of a certain pipe is expressed as in equation (4). Based on equation (4), the cross-sectional area of ​​the sound guide 65 is determined so as to form an RC low-pass filter characteristic that effectively reduces high-frequency distortion components.

[0042]

number

[0043] The inventors conducted experiments and simulations in which the resonant frequency f was used as the calibration frequency. FIG. 6 is a graph showing an example of the results. Specifically, the graph shows the relationship between frequency and sound pressure level when the resonant frequency f is set to 1 kHz, which is the calibration frequency, and the relationship between frequency and the gain of high-frequency distortion components in that case. In FIG. 6, the solid line indicates the frequency characteristics of the acoustic signal output from the sound generator 62, and the thin line indicates the gain of the 1 kHz signal and its distortion components output from the sound generator 62. The solid line indicates the case where the sound guide 65 is formed using the above-mentioned design method, and the dotted line indicates the case where the signal is output directly from the sound generator 61 to the internal space 22 without passing through the sound guide 65.

[0044] As shown in Figure 6, by designing the length and cross-sectional area of ​​sound guide 65 based on equations (1) to (4), the peak frequency of sound generator 62 can be shifted to the calibration frequency. This makes it possible to reduce the electrical signal required to drive sound generator 62, and by reducing the electrical signal, it is also possible to suppress high-frequency distortion components. Furthermore, sound guide 65 functions as an RC low-pass filter, which effectively attenuates high-frequency distortion components.

[0045] (Vent design method) In the coupler 20, there is a concern that noise components from the external space may infiltrate the internal space 22 through the vent 90. Meanwhile, according to Hagen-Poiseuille's law, a resistance component of 8ηl / πr^4 (η is the viscosity of air) occurs in the gas passing through the thin tube. Since the inductance component (see equation (1)) is proportional to 1 / r^2 and the resistance component is proportional to 1 / r^4, the thinner the thin tube, the more dominant the resistance component becomes. Furthermore, the resistance and inductance components increase as the length of the thin tube increases. Based on this, it is preferable to form the vent 90 as long as possible to further reduce noise components from infiltrating the internal space 22 of the coupler 20.

[0046] Furthermore, in coupler 20, a characteristic equivalent to that of an RC low-pass filter is formed by the resistance component due to vent 90 and the capacitance component (see equation (2)) due to internal space 22 of coupler 20. The pass band of noise components entering internal space 22 of coupler 20 through vent 90 is determined based on the characteristics of such an RC low-pass filter. Vent 90 is formed so that the pass band of noise components is a desired frequency.

[0047] The inventors conducted experiments and simulations regarding the relationship between the vent 90 and the level of noise entering the internal space 22 of the coupler 20. Fig. 7 is a graph showing an example of the results. Specifically, the graph shows the relationship between the frequency of the noise component entering the internal space of the coupler and the noise level. In Fig. 7, the comparative example, shown by the thin solid line, is the result of connecting the inner and outer circumferential surfaces of the base end tubular member 43 via a vent that extends linearly in the radial direction.

[0048] Various examples are shown in Figure 8. Example 1 is the result when the central angle of the connecting groove portion 93 is 270° as shown in Figure 8(a), and is shown by the thick solid line in Figure 7. Example 2 is the result when the central angle of the connecting groove portion 93 is 180° as shown in Figure 8(b), and is shown by the dashed line in Figure 7. Example 3 is the result when the central angle of the connecting groove portion 93 is 90° as shown in Figure 8(c), and is shown by the dotted line in Figure 7.

[0049] As shown in Figure 7, when the inner groove portion 91 and the outer groove portion 92 are connected by the connecting groove portion 93, it was confirmed that the larger the central angle of the connecting groove portion 93, i.e., the longer the connecting groove portion 93, the smaller the noise level at each frequency.

[0050] The operation and effects of this embodiment will be described. (1) In the sound calibrator 10, the sound pressure measurement sensor 16 is attached to the sensor attachment port 31 formed in the coupler flange 23 of the coupler 20, making it easy to attach the sound pressure measurement sensor 16. Furthermore, because the output space of the sound generator 62 and the measurement space of the sound pressure measurement sensor 16 and microphone M are shared within the internal space 22 of the coupler 20, the sound pressure applied to the microphone M and the sound pressure applied to the sound pressure measurement sensor 16 can be made the same.

[0051] (2) In the coupler 20, the inductance component of the sound guide 65 and the capacitance component of the internal space 22 of the coupler 20 can generate Helmholtz resonance in the internal space 22 of the coupler 20. The resonant frequency f of the Helmholtz resonance can be adjusted by the cross-sectional area and length of the sound guide 65.

[0052] Furthermore, because the sound guide 65 has a portion that extends in the circumferential direction, there is a high degree of freedom in the length of the sound guide 65, so the sound guide 65 can be designed so that the resonant frequency f becomes a desired frequency. As a result, the electrical input signal required to drive the sound generator 62 can be reduced.

[0053] Furthermore, an RC low-pass filter characteristic is formed by the resistance component of the sound guide 65 and the capacitance component of the internal space 22 of the coupler 20. And, because there is a high degree of freedom in the length of the sound guide 65, it is possible to design the sound guide 65 so as to effectively suppress high frequency distortion components generated by the sound generator 62.

[0054] (3) Since the sound guide path 65 and the sound chamber 61 are formed in the base end tubular member 43, the tip tubular member 41 can be made smaller, and therefore the coupler 20 can be made smaller, compared to when the sound guide path 65 and the sound chamber 61 are formed in the tip tubular member 41, for example.

[0055] Furthermore, for example, if the sound guide 65 is formed in the distal end tubular member 41 and the sound chamber 61 is formed in the proximal end tubular member 43, there is a risk that the sound guide 65 and the sound chamber 61 will be separated due to misalignment between the distal end tubular member 41 and the proximal end tubular member 43 when they are connected. In this regard, by forming the sound guide 65 and the sound chamber 61 in the proximal end tubular member 43, the sound guide 65 and the sound chamber 61 can be directly connected in the same member. This prevents the sound guide 65 and the sound chamber 61 from being separated due to misalignment.

[0056] (4) In the coupler 20, a sealant 72 is disposed in the annular groove 71 that opens to the outside of the sound guide path 65. This prevents sound leakage through the gap between the distal end tubular member 41 and the proximal end tubular member 43. As a result, the sound output by the sound generator 62 can be efficiently transmitted to the internal space 22 of the coupler 20.

[0057] (5) The coupler 20 has a vent 90 that connects the internal space 22 to the external space. The vent 90 has a connecting groove 93 that opens to the connecting surface between the base end tubular member 43 and the coupler flange 23 and extends circumferentially. This configuration allows for greater freedom in the length and path of the vent compared to a vent that extends linearly in the radial direction.

[0058] Furthermore, an RC low-pass filter characteristic is formed by the resistance component of the vent 90 and the capacitance component of the internal space 22 of the coupler 20. The high degree of freedom in the length and path of the vent 90 makes it possible to adjust the RC low-pass filter characteristic. As a result, it is possible to reduce noise components that enter the internal space 22 of the coupler 20 through the vent 90.

[0059] (6) Vent 90 has inner groove portion 91 extending radially, outer groove portion 92 extending radially, and connecting groove portion 93 extending circumferentially and connecting these. Because the various groove portions extend in directions defined by central axis 24A in this manner, machining for forming vent 90 can be easily performed.

[0060] (7) The connecting groove portion 93 is formed at a position closer to the base-end fastening hole 74 in the radial direction than the inner circumferential surface of the internal space 22. This increases the length of the connecting groove portion 93 per unit angle in the circumferential direction. As a result, a longer vent 90 can be formed.

[0061] (8) The connecting groove portion 93 connects the outer groove portion 92 and the inner groove portion 91 on the preferential angle side of the angle formed by the outer groove portion 92 and the inner groove portion 91 in the circumferential direction. This allows the length of the connecting groove portion 93 to be longer when connecting the outer groove portion 92 and the inner groove portion 91.

[0062] (9) The vent 90 is formed in the base-end tubular member 43. This reduces the number of machining steps required to form the vent 90 compared to, for example, a case in which the outer groove 92 is recessed into the base-end surface 43b of the base-end tubular member 43 and the inner groove 91 and the connecting groove 93 are recessed into the flange-side coupling surface 23a of the coupler flange 23.

[0063] This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility. In the above embodiment, the coupler flange 23 is composed of the flange main body 27 and the auxiliary connection plate 28. However, the configuration is not limited to this, and the coupler flange 23 may be configured such that the flange main body 27 and the auxiliary connection plate 28 are integrated into one piece.

[0064] In the above embodiment, the coupler 20 has a sealant 72 that is disposed in an annular groove 71 that opens to the outside of the sound guide path 65 and that seals between the tip tube member 41 and the base end tube member 43. This annular groove 71 may be configured to open to the base end surface 41b of the tip tube member 41. Note that the annular groove 71 and the sealant 72 are not essential components of the sound calibrator 10.

[0065] In the above embodiment, the sound guide path 65 and the sound chamber 61 are formed in the base end tubular member 43. However, this is not limited to this, and for example, the sound guide path 65 may be formed in the base end tubular member 43, and the sound chamber 61 may be formed in the tip end tubular member 41. Alternatively, for example, the sound guide path 65 may be formed in the tip end tubular member 41, and the sound chamber 61 may be formed in the base end tubular member 43.

[0066] In the above embodiment, the first sound guide portion 66 of the sound guide path 65 has a portion that extends in the circumferential direction. However, the first sound guide portion 66 may be configured to extend linearly, or may be configured to extend in the circumferential direction so as to gradually approach the inner circumferential surface, based on the above-mentioned design method.

[0067] In the above embodiment, the vent 90 is recessed in the base end surface 43b, which is the connection surface of the base end tubular member 43 with respect to the coupler flange 23. However, the present invention is not limited to this, and the vent 90 may be recessed in the flange-side connection surface 23a of the coupler flange 23 as long as it opens into the connection surface between the coupler flange 23 and the base end tubular member 43. Furthermore, the vent 90 may be configured such that a portion of the vent 90 is recessed in the base end surface 43b of the base end tubular member 43, and the other portion is recessed in the flange-side connection surface 23a of the coupler flange 23.

[0068] In the above embodiment, the connection groove 93 is formed at a position radially closer to the base-end fastening hole 74 than the inner circumferential surface of the coupler 20. However, the connection groove 93 may be formed at a midpoint in the radial direction between the inner circumferential surface of the coupler 20 and the base-end fastening hole 74, or may be formed at a position closer to the inner circumferential surface of the coupler 20 than the base-end fastening hole 74.

[0069] In the above embodiment, the vent 90 is composed of an inner groove 91, an outer groove 92, and a connecting groove 93. However, the vent 90 is not limited to this, and may be configured in a spiral shape that connects the internal space 22 of the coupler 20 to the external space of the coupler 20 while avoiding interference with the sound chamber 61 and the base-end fastening hole 74, as shown in Fig. 9 .

[0070] The technical ideas that can be understood from the above-described embodiment and modified examples will be described. (Appendix 1) The acoustic calibrator has a groove-shaped vent that connects the internal space of the coupler body with the external space of the coupler body, opens to the connecting surface between the coupler flange and the base end tubular member, and has a portion that extends circumferentially of the coupler body.

[0071] This configuration allows for greater flexibility in the length and path of the vent compared to vents that extend radially from the coupler body. Furthermore, the RC low-pass filter characteristics are formed by the resistance component of the vent and the capacitance component of the internal space of the coupler body. The greater flexibility in the length and path of the vent allows for adjustment of the RC low-pass filter characteristics. As a result, noise components entering the internal space of the coupler body through the vent can be reduced.

[0072] (Appendix 2) The vent includes an outer groove extending radially of the coupler body and communicating with the external space of the coupler body, an inner groove formed at a position different from the outer groove in the circumferential direction of the coupler body and extending radially of the coupler body and communicating with the internal space of the coupler body, and a connecting groove connecting an inner end of the outer groove to an outer end of the inner groove and extending circumferentially of the coupler body. With this configuration, the various grooves extend in a direction defined by the central axis of the coupler body, which facilitates machining to form the vent.

[0073] (Appendix 3) The base end tubular member has a base end fastening hole into which a base end fastening member extending in the axial direction of the coupler body and connecting the coupler flange and the base end tubular member is fastened, and it is preferable that the connection groove portion is formed at a position radially of the coupler body closer to the base end fastening hole than the circumferential surface of the internal space.

[0074] According to the above configuration, the connecting groove is disposed at a position far from the circumferential surface of the internal space, so that the vent length per unit angle in the circumferential direction of the coupler body can be increased, thereby forming a longer vent.

[0075] (Appendix 4) The connecting groove connects the outer groove and the inner groove on the more favorable angle side of the angle formed by the outer groove and the inner groove in the circumferential direction of the coupler. With this configuration, the length of the connecting groove can be increased when connecting the outer groove and the inner groove.

[0076] (Appendix 5) The vent is formed in the tubular proximal end member. According to the above configuration, the number of machining steps required to form the vent can be reduced compared to, for example, when the outer groove portion is formed in the base end tubular member and the inner groove portion and the connecting groove portion are formed in the coupler flange. [Explanation of symbols]

[0077] M...microphone, 10...sound calibrator, 11...housing, 12...front member, 12a...front wall, 13...rear member, 13a...rear wall, 14...coupler insertion hole, 15...electronic board, 16...sound pressure measurement sensor, 16A...sensing unit, 18...standoff, 19...spacer, 20...coupler, 21...insertion port, 22...internal space, 23...coupler flange, 23a...flange side coupling surface, 24...coupler body, 24A...central axis, 25...mounting fastening member, 26...spacer fastening member, 27...flange body, 28...coupling auxiliary plate, 30...flange fastening member, 31...sensor mounting port, 32...mounting port sealant, 33...sealing recess, 41...tip tube Component, 41b...base end surface, 43...base end tube component, 43a...tip surface, 43b...base end surface, 45...tip side fastening member, 46...base end side fastening member, 51...tip tube main body, 52...flange portion, 53...locking portion, 54...sealing groove portion, 55...insertion port sealing material, 56...tip connecting hole, 61...sound chamber, 62...sound producing body, 62a...output port, 63...main body through hole, 64...auxiliary plate through hole, 65...sound guide path, 66...first sound conducting portion, 67...second sound conducting portion, 71...annular groove, 72...sealing material, 73...tip side fastening hole, 74...base end side fastening hole, 75...main body connecting hole, 76...auxiliary plate connecting hole, 81...protective grid, 90...vent, 91...inner groove portion, 92...outer groove portion, 93...connecting groove portion.

Claims

1. a cylindrical coupler body having a socket into which a microphone is inserted and an internal space communicating with the socket; a coupler flange connected to the coupler body from the opposite side of the insertion port and having a sensor mounting port communicating with the internal space; a sound pressure measurement sensor that measures sound pressure in the internal space, the sound pressure measurement sensor having a sensing portion that is disposed in the internal space through the sensor mounting port; a sound-generating body that outputs sound into the internal space, The coupler body includes: a tip tube member having the insertion port formed therein; a base end cylindrical member to which the coupler flange is connected; a groove-shaped sound guide path that communicates with the internal space and opens onto a connecting surface between the tip tube member and the base end tube member; a sound-producing chamber communicating with the sound guide path and in which the sound-producing body is disposed, The sound generating body is Sound is output to the internal space through the sound guide path. Sound calibrator.

2. The sound guide path has a portion extending in the circumferential direction of the coupler body. The sound calibrator of claim 1 .

3. The sound guide path and the sound-producing chamber are formed in the base end cylindrical member. The sound calibrator of claim 2 .

4. The coupler body includes a seal member disposed outside the sound guide path to seal the gap between the distal end tubular member and the proximal end tubular member. The sound calibrator of claim 3 .

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