Acoustic coupler device

Abstract

This invention provides a technique suitable for calibration operations in a wide bandwidth. The acoustic coupler device includes: a microphone support capable of housing a monitoring microphone and a reference microphone or a microphone to be calibrated, with a calibration space formed between their respective protective mesh front faces; a piezoelectric vibrator generating a high-frequency calibration tone; a speaker unit generating a low-frequency calibration tone as a diaphragm is driven; a silicone tube communicating the space divided by the diaphragm and the rear space to the outside air; a sound guide channel communicating between the outer side of the microphone support and the calibration space; and a silicone tube communicating between the sound guide channel and the front space divided by the diaphragm of the speaker unit, guiding the low-frequency calibration tone into the calibration space through the sound guide channel, and communicating the calibration space to the outside air through the silicone tube.

Description

Technical Field

[0001] This invention relates to an acoustic coupler device for microphone calibration. Background Technology

[0002] Generally, in addition to calibration methods using multi-frequency acoustic calibrators and comparator couplers, calibration methods using electrostatic drivers, anechoic chambers, and acoustic chambers are also known for calibrating microphones and noise meters used for measurement. Among these, the use of a comparator coupler ("acoustic coupler") allows for high-precision calibration without requiring a large space or equipment like an anechoic chamber. Therefore, calibration methods using acoustic couplers are also employed in testing facilities and the like (see, for example, the explanation in Non-Patent Document 1).

[0003] Furthermore, as prior art related to acoustic couplers, there are known sound calibrators (for example, see Patent Document 1) that have a structure in which a reference microphone and a microphone to be calibrated are positioned opposite and supported in a small space. In this prior art, when a signal sound field is generated by a loudspeaker in the small space within the sound calibrator, the microphone to be calibrated can be calibrated based on the characteristic difference of the sound pressure measured by the two microphones.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 1-217216 ( Figure 4 )

[0007] Non-patent literature

[0008] Non-patent literature 1: IEC61094-5:2016 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] In recent years, there has been a growing demand for microphones and noise meters capable of measuring / analyzing a wide frequency range, from a few Hz in ultra-low frequencies to 20 kHz, which is considered the limit of human hearing. Therefore, for equipment designed for wide-bandwidth measurement and analysis, microphone calibration is required within that bandwidth.

[0011] However, beyond the calibration methods using existing acoustic couplers, conventional calibration methods have limitations on the frequency band of sound that can be generated in a single calibration. This results in the inability to complete calibration across a wide frequency band exceeding these limits in a single operation. Therefore, calibration operations in testing facilities require multiple acoustic couplers generating sound in both low and high frequency ranges, and measurements are performed more than twice in each range to cover the wide frequency band. In such cases, the following problems arise: pre-operation checks and setup of the testing equipment require significant time, or large equipment and suitable installation locations must be specifically prepared.

[0012] Furthermore, free-field microphones are generally widely used as noise meters and measurement microphones. Free-field microphones are designed with a static pressure adjustment port that connects the space surrounded by the back of the diaphragm and insulation to the outside world. With sound pressure exposed to the front surface of the diaphragm and the static pressure adjustment port, they achieve a flat frequency response from high to low frequencies. However, the location of the static pressure adjustment port varies depending on the free-field microphone model. Therefore, if all microphone models are calibrated uniformly, the sound pressure may not be exposed to the static pressure adjustment port within the sealed structure of the acoustic coupler due to model differences, resulting in a failure to obtain the original free-field sensitivity level in the low-frequency range. Similarly, when calibrating a sound pressure field microphone used for purposes such as creating a reference sound field, the free-field sensitivity level in the low-frequency range corresponding to the target may not be obtained. To avoid these problems, the following significant issues arise: multiple acoustic couplers and fixtures with different structures must be used depending on the model of the microphone being calibrated (the location of the static pressure adjustment port), or the low-frequency range correction amount must be calculated and calibrated each time.

[0013] Therefore, the present invention provides a technique suitable for calibration operations in a wide bandwidth.

[0014] Solution for solving the problem

[0015] This invention provides an acoustic coupler device. The acoustic coupler device includes a first sound source and a second sound source, capable of generating calibration tones with different frequency bands from each sound source, thus covering a wide frequency band (e.g., 1Hz to 20kHz). Three types of microphones related to calibration are included: a first microphone (a monitoring microphone with a built-in coupler) and a second microphone (a reference microphone or a microphone to be calibrated inserted into the coupler with a known sound pressure sensitivity level), which are housed inside a support member. The support member houses multiple microphones (the first microphone and the second microphone), forming a calibration space between their respective protective mesh front faces. A first sound guide channel communicating with the outside of the support member guides the first calibration tone from the first sound source into the calibration space. Furthermore, a second sound guide channel communicates with the first sound guide channel, allowing a second calibration tone from the second sound source to be guided into the calibration space through the first sound guide channel and the second sound guide channel. Therefore, wideband calibration operations can be performed without the need for multiple calibration devices.

[0016] Furthermore, in this invention, static pressure adjustment of the sound field surrounding the first and second sound sources, including the calibration space, can be performed when either the first calibration tone or the second calibration tone is generated. The front faces of the protective mesh of the first and second microphones are positioned opposite each other in the calibration space, and the first sound guide channel, which communicates with the calibration space, is also connected to the second sound guide channel. Moreover, the second sound guide channel communicates with the space on the front side defined by the diaphragm of the second sound source, and both the space on the front and rear sides defined by the diaphragm are connected to the outside air via connecting paths. Therefore, static pressure adjustment can be performed when the first calibration tone is generated by the first sound source and when the second calibration tone is generated by the second sound source, thus enabling broadband calibration.

[0017] In this respect, without reliable and proper hydrostatic adjustment, the driving of the first or second sound source will become unstable, failing to output a stable calibration tone. Therefore, it cannot be said to be fully applicable to calibration operations in wideband applications such as measuring microphones; it is technically inadequate.

[0018] In contrast, the acoustic coupler device of the present invention reliably and appropriately performs hydrostatic adjustment for any frequency band in both the low-frequency and high-frequency ranges (i.e., in a wide frequency band), and is therefore advantageous in terms of being able to perform stable calibration over a wide frequency band.

[0019] This invention also corresponds to the static pressure adjustment of the microphone (i.e., the second microphone) related to calibration. Specifically, the first and second microphones are housed within a support member, where the sides of each microphone are surrounded by the inner wall of the support member body. The gap between this inner wall and the protective mesh side of each microphone is sealed by a first sealing member to achieve airtightness. This ensures airtightness within the calibration space and allows the calibration tone to be exposed to the static pressure adjustment holes on the front side of the protective mesh of each microphone.

[0020] However, when the microphone related to calibration (that is, the second microphone) is in a structure where hydrostatic adjustment is performed on a part other than the front face of the protective grid, ensuring airtightness through the aforementioned first sealing member becomes an obstacle to the hydrostatic adjustment of the microphone.

[0021] Therefore, in this invention, for example, the gap between the side of the second microphone and the inner wall of the support member body is made to communicate with the outside of the support member body at positions between the front end face of the protective mesh and the first sealing member, and between the first sealing member and the second sealing member, respectively. Furthermore, in the case of a microphone for calibration measurement, a preamplifier with a slit formed in a portion of the circumferential direction of the microphone joint is used to communicate with the outside of the support member body through the space on the back side of the second microphone housing. Thus, even if the microphone related to calibration (i.e., the second microphone) is in a structure where hydrostatic adjustment is performed at a location other than the front end face of the protective mesh (e.g., the side of the protective mesh or the back side of the housing), since the calibration tone is exposed to the hydrostatic adjustment hole, it is not necessary to change the acoustic coupler device according to the microphone model, nor is it necessary to set clamps or low-frequency range correction amounts; the same calibration as in a free sound field is achieved in the low-frequency range.

[0022] The acoustic coupler device of the present invention has the following preferred embodiments.

[0023] (1) The first sound source has, for example, a piezoelectric vibrator. The piezoelectric vibrator is cylindrical and is arranged to surround the support member. By the radial vibration of the piezoelectric vibrator, a first calibration tone in, for example, a high-frequency range can be generated. Furthermore, the piezoelectric vibrator is held by a vibration damper, thereby suppressing the transmission of the vibration of the piezoelectric vibrator to the support member including the first microphone and the second microphone.

[0024] (2) In the scheme described in (1) above, the piezoelectric vibrator is cylindrical, and therefore the vibration damping member is an annular shape that holds the piezoelectric vibrator at both ends. Thus, the transmission of vibration to the support member, etc., is suppressed throughout the circumference relative to the radial vibration of the piezoelectric vibrator. Furthermore, since the support member is surrounded by the cylindrical piezoelectric vibrator, a slit formed in a portion of the circumference of the vibration damping member holding one end edge of the piezoelectric vibrator is appropriately utilized in the connection between the first and second sound channels. This slit ensures air permeability and connects the outer and inner sides of the piezoelectric vibrator. Therefore, the connection between the first and second sound channels located inside the piezoelectric vibrator and static pressure adjustment can be performed, and the second calibration tone generated by the second sound source can be introduced into the calibration space.

[0025] (3) A support member is housed inside the housing. This housing, by surrounding the first sound source (including the case of a piezoelectric vibrator) together with the support member on its outer side, forms a separate coupler within the acoustic coupler device. Thus, an environment suitable for calibration using the first sound source is appropriately constructed. Furthermore, the first calibration tone is also generated outside the first sound source; therefore, if the first calibration tone is reflected back to the housing, it could become a source of interference. Therefore, a sound-absorbing element is provided outside the housing to absorb the first calibration tone. This prevents interference caused by reflection and appropriately maintains the environment for calibration.

[0026] (4) A vibration suppression member is disposed between the first sound source and the second sound source. As described in the above scheme (3), when a single coupler is disposed inside the coupler device, the transmission of vibration from the second sound source to the support member housing the first and second microphones would adversely affect the calibration, which is not preferable. Therefore, the vibration suppression member can suppress the transmission of vibration from the second sound source to the support member, maintaining calibration accuracy. In addition, the vibration suppression member fixes a single coupler inside the acoustic coupler device, and at the same time, it also serves to absorb / mitigate / disperse the impact on the coupler containing the support member when the second microphone is inserted.

[0027] (5) The acoustic coupler device has a housing, in which at least a support member, a first sound source, and a second sound source are housed. A first sound guide channel and a second sound guide channel are also housed separately within the housing. A foot is provided on the lower surface of the housing, allowing the housing to be placed in a predetermined posture (e.g., upright). This structure stably secures the acoustic coupler device, ensuring convenience and reliability for calibration operations. Furthermore, the communication path related to static pressure adjustment employs a structure that connects to the external air from the inside of the housing through the non-mounted surface of the foot. This structurally solves problems such as the possibility of the communication path opening on the lower surface of the housing becoming blocked due to mounting conditions, or the opening being blocked by labels affixed to the lower surface of the housing. With a structure that opens to the external air through the non-mounted surface of the foot, the communication path will not be blocked even when the housing is mounted, enabling reliable internal static pressure adjustment.

[0028] Invention Effects

[0029] As described above, the present invention provides a technique suitable for calibration operations in a wide bandwidth. Attached Figure Description

[0030] Figure 1 This is a perspective view showing the external shape of an acoustic coupler device 100 according to one embodiment.

[0031] Figure 2 This is a longitudinal section view of the acoustic coupler device 100 (along... Figure 1 (Sectional view of line II-II in the middle).

[0032] Figure 3 It is by Figure 2 An enlarged view of the area represented by the circle with a single dotted line.

[0033] Figure 4 This is an exploded perspective view showing the external shape of the microphone support 124 and the piezoelectric vibrator 128.

[0034] Figure 5 This is a horizontal sectional view (along the distance) of the microphone support 124 at the location of spacer 124b and mouthpiece 124c. Figure 4 (Cross-sectional view of the V-V line in the diagram).

[0035] Figure 6 This is a diagram illustrating a process example of a calibration method using the acoustic coupler device 100.

[0036] Explanation of reference numerals in the attached figures

[0037] 100: Acoustic coupler device; 102: Housing; 110: Foot; 120: First coupler; 122: Receptacle; 122d: Sound guide channel; 124: Microphone support; 124g, 124h: Ventilation path; 126: Sealing component; 128: Piezoelectric vibrator; 130, 132: Rubber pad; 132a: Slit; 134: Sound absorber; 138: Ultra-soft polyurethane; 140: Second coupler; 144: Speaker unit; 150, 152, 154: Silicone tubing. Detailed Implementation

[0038] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the structure of the acoustic coupler device shown in the following embodiments is a preferred example, and the present invention is not limited to this example. Furthermore, the name "acoustic coupler device" is not limited to this; terms such as "acoustic coupler" and "comparison coupler" may also be used.

[0039] Figure 1 This is a perspective view showing the external shape of an acoustic coupler device 100 according to one embodiment. The acoustic coupler device 100 includes a generally cylindrical housing 102, which is constructed by combining a cylindrical side plate 104, a circular flange-shaped bottom plate 106, and a disk-shaped top plate 108. Furthermore, pad-like feet 110 are fitted onto the lower surface of the housing 102 (the lower surface of the bottom plate 106). In this embodiment, for example, three feet 110 are arranged at equal intervals in the circumferential direction. The housing 102 of the acoustic coupler device 100 is fixed to a mounting surface of, for example, a mounting platform (not shown) via the feet 110, and is held in a position such that, for example... Figure 1 The standing posture is shown. The material of the foot 110 can be, for example, a shock-absorbing material (shock-absorbing rubber, resin, etc.), but is not limited to this.

[0040] The acoustic coupler device 100 has a knurled knob 112 protruding from the center of the top plate 108, and a circular insertion port 112a is formed at the center of the knurled knob 112. The insertion port 112a narrows in a funnel shape from the upper surface of the knurled knob 112 toward the depth direction (downward), and communicates with the interior of the housing 102 while maintaining a constant inner diameter.

[0041] In the acoustic coupler device 100, a reference microphone Ms or a calibrated microphone Mp (both second microphones) is inserted externally through the aforementioned insertion port 112a. The reference microphone Ms or the calibrated microphone Mp is connected to, for example, a preamplifier PA2. Furthermore, the preamplifier PA2 may be connected to a measuring instrument MI, a noise meter, etc., as shown in the figure, or it may be connected to an external device not shown. Protective meshes for protecting the microphone diaphragms are attached to the top of the reference microphone Ms, the calibrated microphone Mp, and the monitoring microphone Mm (first microphone) described later. Slits, etc., are provided in the protective meshes through which sound pressure is transmitted to the diaphragms. In this embodiment, an example of calibration is described by connecting a 1 / 2-inch measuring microphone (a condenser microphone of the shape / size specified according to IEC 61094-4) to a preamplifier corresponding to the insertion voltage method (IEC 61094-2). In addition, the reference microphone Ms adopts a working standard with calibrated sound pressure sensitivity level (a condenser microphone calibrated according to a specific standard and conforming to IEC 61094-4).

[0042] A connector 113 is provided on the side of the housing 102 (side plate 104), and the connector 113 is located inside the housing 102 and connects to various electrical systems. Figure 1 (Not shown in the image) is connected. The acoustic coupler device 100 can be connected to an external device (not shown in the image) via connector 113 during calibration. Figure 1 (The connection is not shown in the image).

[0043] [Internal Structure]

[0044] Figure 2 This is a longitudinal section view of the acoustic coupler device 100 (along... Figure 1 (Cross-sectional view of line II-II in the diagram). Furthermore... Figure 3 It is by Figure 2 An enlarged view of the area represented by the circle with a single dotted line. See below, as appropriate. Figure 2 and Figure 3 Please provide an explanation.

[0045] The acoustic coupler device 100 includes a first coupler 120 and a second coupler 140, and the housing 102 has a volume sufficient to accommodate the two couplers 120 and 140. The first coupler 120 is located at the top inside the housing 102, and the second coupler 140 is located below it.

[0046] The first coupler 120 is mounted on the lower surface of the top plate 108. The first coupler 120 is equipped with a monitoring microphone Mm and a preamplifier PA1, and is housed together with these components inside the housing 102. The monitoring microphone Mm measures the sound pressure inside the first coupler 120, and the preamplifier PA1 performs impedance transformation on the output of the monitoring microphone Mm. In the preamplifier PA1, an electrical system connection line 113b extends from a connector 113, allowing the preamplifier PA1 and the monitoring microphone Mm to be driven / controlled via an external device connected to the connector 113.

[0047] [Structure of the first coupler]

[0048] The first coupler 120 mainly includes a housing 122, a microphone support 124, and a piezoelectric vibrator 128. The housing 122 maintains its positional relationship while housing the microphone support 124 and the piezoelectric vibrator 128 inside it.

[0049] [Supporting Components]

[0050] The microphone support 124 is generally cylindrical in shape and connected to the insertion port 112a that opens on the upper surface of the housing 102 (knurled knob 112). The aforementioned monitoring microphone Mm is housed inside the microphone support 124. Furthermore, the microphone support 124 can also house a reference microphone Ms or a calibration microphone Mp that is inserted from outside the housing 102.

[0051] In addition, such as Figure 3 As shown in the magnified view, the microphone support 124 has a cylindrical body that houses the monitoring microphone Mm and the reference microphone Ms or the calibrated microphone Mp along its inner wall surface 124a. In this state, the microphone support 124 allows the front faces of the protective mesh of the monitoring microphone Mm and the reference microphone Ms or the calibrated microphone Mp (referring to the front face of the protective mesh Gr; the same applies hereinafter) to face each other, maintaining a calibration space Sp between them. Therefore, a plurality of spacers 124b protruding from the inner wall surface 124a toward the center are formed inside the microphone support 124, and the calibration space Sp is ensured by the height (thickness) of the spacers 124b between the front faces of the protective mesh of the monitoring microphone Mm and the front faces of the protective mesh of the other reference microphone Ms or the calibrated microphone Mp. It should be noted that the spacing of the calibration space Sp can be set to, for example, 1.5 mm, but is not limited to this.

[0052] [First Sound Guide Channel]

[0053] In the microphone support portion 124, sound ports 124c are formed at equal intervals in multiple circumferential locations, and the sound ports 124c extend from the inner wall surface 124a of the microphone support portion 124 to the outer surface. Thus, the calibration space Sp is connected to the outside of the microphone support portion 124 through the sound ports 124c. Furthermore, in the microphone support portion 124, a narrowed portion 124d is formed on the outer side around the calibration space Sp, in which the main body of the microphone support portion 124 is partially narrowed, thereby forming a sound guiding channel 122d between the outer side of the sound ports 124c and the piezoelectric vibrator 128.

[0054] Figure 4 This is an exploded perspective view showing the external shape of the microphone support 124 and the piezoelectric vibrator 128. Furthermore, Figure 5 This is a horizontal sectional view (along the distance) of the microphone support 124 at the location of spacer 124b and mouthpiece 124c. Figure 4 (Cross-sectional view of the V-V line in the diagram). Below, except... Figure 2 and Figure 3 Also refer to Figure 4 and Figure 5 Please provide an explanation.

[0055] [First sound source]

[0056] like Figure 4 As shown, the piezoelectric vibrator 128 described above also has a cylindrical shape, with its inner diameter larger than the outer diameter of the microphone support 124. The piezoelectric vibrator 128 has a height (axial length) exceeding the range occupied in the height direction by the protective mesh sides of the two microphones (Mm, Ms / Mp) housed in the microphone support 124. Viewed in the height direction, the height of the calibration space Sp coincides precisely with the center of the cylindrical shape of the piezoelectric vibrator 128 in the height direction. This piezoelectric vibrator 128 is arranged outside the microphone support 124 in a manner that surrounds it. In the piezoelectric vibrator 128, the electrical system connection line 113a extends from the connector 113, allowing the piezoelectric vibrator 128 to be driven / controlled via an external device connected to the connector 113. The piezoelectric vibrator 128 vibrates radially with the application of a driving voltage, outputting, for example, a sound from 1kHz to 20kHz (a calibration tone in the high-frequency band). As an example, the inner diameter and length of the piezoelectric vibrator 128 can be set to... Around 20mm, but not limited to that.

[0057] like Figures 2-5As shown, all microphones Mm, Ms, Mp, microphone support 124, piezoelectric vibrator 128, and sound-absorbing element 134 are arranged coaxially. This allows for the homogenization of sound pressure within the calibration space Sp in the high-frequency band, or the maintenance of a high signal-to-noise ratio above a certain level. As an example, the density and thickness of the sound-absorbing element 134 can be set to 0.5 g / cm³. 3 It is about 2mm, but not limited to that.

[0058] [Sealing components]

[0059] Furthermore, in the microphone support portion 124, two sealing members 126 (O-rings as the first component of the present invention) are provided corresponding to the monitoring microphone Mm and other reference microphones Ms or calibrated microphone Mp, respectively. Two annular grooves 124e are formed along the inner wall surface 124a of the microphone support portion 124, and the two sealing members 126 are configured to be embedded in the corresponding grooves 124e. The lower sealing member 126 seals the gap between the inner wall surface 124a of the microphone support portion 124 and the protective mesh side surface of the monitoring microphone Mm (meaning the side surface of the protective mesh Gr; the same applies hereinafter). The upper sealing member 126 seals the gap between the inner wall surface 124a and the protective mesh side surface of the inserted microphone (reference microphone Ms or calibrated microphone Mp) to achieve an airtight seal. The sealing members 126 prevent sound leakage from the calibration space Sp. The rubber pad 125 (the second sealing member of the present invention) located on the lower side of the knurled knob 112 will be described later.

[0060] [Ventilation path]

[0061] To calibrate the low-frequency range under conditions identical to a free sound field, the sound pressure (calibration tone) must be exposed not only to the front surface of the microphone diaphragm but also to the static pressure adjustment hole. As described above, the protective mesh sides of each microphone Mm, Ms, and Mp are sealed by a sealing member 126 (O-ring) to achieve airtightness. For the monitoring microphone Mm, which is built into the acoustic coupler device 100, a model of microphone capable of static pressure adjustment on the front surface of the protective mesh is used, allowing the calibration tone to be actively exposed to the static pressure adjustment hole (not shown). On the other hand, for the externally inserted reference microphone Ms or the calibrated microphone Mp, it is also assumed that static pressure adjustment is performed on the protective mesh side or the back of the housing, outside the front surface of the protective mesh. Two ventilation paths 124g and 124h are formed in the microphone support 124. Furthermore, a static pressure adjustment hole PA2a is also formed in the preamplifier PA2. One of the microphone supports 124 (in...) Figure 3The ventilation path 124g (observed from below) opens on the inner wall surface 124a at a position between the front end face of the protective mesh of the inserted reference microphone Ms or the calibrated microphone Mp and the sealing member 126, penetrating the body radially and communicating with the outside. The other side (in...) Figure 3 The vent 124h (observed from above) opens on the inner wall surface 124a between the sealing member 126 and the rubber pad 125, radially penetrating the main body and communicating with the outside. The static pressure adjustment hole PA2a of the preamplifier PA2 opens on the inner wall surface 124a between the sealing member 126 and the rubber pad 125, communicating with the outside of the main body via the vent 124h. Thus, the space below and above the sealing member 126, located in the gap between the side of the reference microphone Ms or the calibrated microphone Mp and the inner wall surface 124a, and the space on the back of the housing of the reference microphone Ms or the calibrated microphone Mp, are in a state of communication with the outside of the microphone support 124. Therefore, regardless of the position of the microphone's static pressure adjustment hole, the calibration tone is exposed to the static pressure adjustment hole of the inserted reference microphone Ms or the calibrated microphone Mp, obtaining the same calibration result as a free sound field in the low-frequency range. It should be noted that... Figure 2 and Figure 3 For convenience, the cross-sections of ventilation paths 124g, 124h, and sound port 124c are shown to be within the same cross-section, but if... Figure 4 As shown, the positions of ventilation paths 124g, 124h and sound port 124c can also be different in the circumferential direction.

[0062] [Container]

[0063] exist Figure 2 and Figure 3 Only a cross-section is shown, but the housing 122 is generally cylindrical in shape, with circular openings on its upper and lower surfaces. Furthermore, the opening on the upper surface protrudes in a boss shape, and the upper end of this protrusion is formed into a tapered surface 122e that slopes downwards towards the center. The housing 122 is held in place by a rubber pad 125 sandwiched between the tapered surface 122e at its upper end and the knurled knob 112, sealing the opening on the upper surface of the housing 122 with the rubber pad 125. Additionally, the upper end of the microphone support 124 is also formed with the same tapered surface 124f, and the tapered surfaces 124f of the microphone support 124 and 122e of the housing 122 are arranged to be connected on the same plane. Therefore, the microphone support 124 is also held in place by inserting a rubber pad 125 between the upper conical surface 124f and the knurled knob 112, and the opening at the upper end of the microphone support 124 is sealed by the annular rubber pad 125. It should be noted that the inner diameter of the rubber pad 125 is large enough to allow the preamplifier PA2, the reference microphone Ms, or the calibrated microphone Mp to be inserted.

[0064] On the other hand, the central portion of the top plate 108 of the housing 102 is formed in the shape of a boss protruding upward, and an internal thread is formed in the central portion. The knurled knob 112 is formed with an external thread 112b corresponding to the internal thread in the central portion, and is assembled with the external thread 112b screwed into the internal thread on the side of the top plate 108.

[0065] When the knurled knob 112 is tightened with the preamplifier PA2 (with the reference microphone Ms or the calibrated microphone Mp connected) inserted into the insertion port 112a, the rubber pad 125 is flattened along the downward slope of the conical surfaces 122e and 124f, and firmly seals against the outer surface of the preamplifier PA2. Thus, by securing and fixing the reference microphone Ms or the calibrated microphone Mp together with the inserted preamplifier PA2, sequential calibration can be performed (refer to IEC61094-5:2016 Annex BB.2).

[0066] Furthermore, the aforementioned preamplifier PA1 is inserted into the opening on the lower surface of the housing 122, thereby connecting the monitoring microphone Mm to the preamplifier PA1. Additionally, the housing 122 and the preamplifier PA1 are connected via a connecting member 136.

[0067] Furthermore, the container 122 has multiple receiving portions 122a, 122b, and 122c corresponding to the shape and arrangement of the object being contained. These receiving portions 122a, 122b, and 122c are formed in a concentric circle from the center of the container 122 outwards. The innermost receiving portion 122a houses the aforementioned microphone support portion 124. The middle receiving portion 122b houses the aforementioned piezoelectric vibrator 128. The outermost receiving portion 122c houses a sound-absorbing member 134. This sound-absorbing member 134 absorbs the sound generated by the piezoelectric vibrator 128 and suppresses sound reflections from the wall of the container 122.

[0068] [Vibration-proof parts]

[0069] Here, the piezoelectric vibrator 128 is housed within the receiving portion 122b, with its upper and lower end edges held in place by rubber pads 130 and 132, respectively. The rubber pads 130 and 132 are annular in shape to match the shapes of the upper and lower end edges of the piezoelectric vibrator 128, and have a groove-shaped (channel-shaped) cross-section that encloses the upper and lower end edges. These rubber pads 130 and 132 prevent the vibration of the piezoelectric vibrator 128 from being directly transmitted to the receiving body 122 and the microphone support portion 124 (monitoring microphone Mm, reference microphone Ms, or calibrated microphone Mp). As an example, the groove depth and thickness of the rubber pads 130 and 132 can be set to approximately 1 mm and 0.5 mm, respectively, but are not limited to these values. Furthermore, as an example, the volume of the space (sound guide channel 122d and calibration space Sp) surrounded by the rubber pads 130, 132, piezoelectric vibrator 128, and microphone support 124 (monitoring microphone Mm, reference microphone Ms, or calibrated microphone Mp) can be set to about 1cc, but is not limited to this.

[0070] [Narrow slit]

[0071] A slit 132a is formed in a portion of the circumferential direction on the rubber pad 132 that holds the lower edge of the piezoelectric vibrator 128. Figure 2 and Figure 3 The diagram shows the rubber pad 132 on the lower side at the position of the cross-section of slit 132a. Slit 132a connects the inner and outer sides of the piezoelectric vibrator 128 inside the housing 122. Thus, the outer side of the piezoelectric vibrator 128 is connected to the sound guiding channel 122d located inside it.

[0072] [Second sound guide channel]

[0073] Here, the acoustic coupler device 100 includes a silicone tube 150 that connects the first coupler 120 and the second coupler 140. Specifically, one end of the silicone tube 150 passes through the housing 122 of the first coupler 120 and extends from the outside to the inside of the housing portion 122b, with its open end located at a position that has a gap with the slit 132a of the rubber pad 132. Furthermore, the other end of the silicone tube 150 extends into the interior of the second coupler 140. Thus, the sound guiding channel 122d located on the outside and inside of the piezoelectric vibrator 128 is connected to the interior of the second coupler 140. The second coupler 140 will be described below.

[0074] [Second Coupler]

[0075] The second coupler 140 is mounted on the upper surface of the base plate 106. The second coupler 140 is a structure that houses the speaker unit 144 inside a transversely cup-shaped enclosure 142. Regarding the internal structure, although the illustration is simplified, the speaker unit 144 is a conductive type that vibrates the diaphragm 144a by means of an electromagnetic coil (voice coil), and for example, it is a sound source (second sound source) that emits low-frequency sounds in the range of 1Hz to 800Hz. In the speaker unit 144, the electrical system connection line 113c extends from the connector 113, and the speaker unit 144 can be driven / controlled by an external device connected to the connector 113.

[0076] Here, the enclosure 142 keeps the area around the speaker unit 144 airtight. Inside the enclosure 142, a diaphragm 144a divides the space into a front (sound emission side) space 146 and a rear space 148. The aforementioned silicone tube 150 communicates with the front space 146. Therefore, the sound (second calibration tone) generated by the speaker unit 144 as the diaphragm 144a vibrates is transmitted to the first coupler 120 through the silicone tube 150, and thus introduced into the calibration space Sp from the slit 132a through the sound guide channel 122d. As an example, the volume of the front space 126 can be set to approximately 5 cc, but it is not limited to this.

[0077] [Connecting Path]

[0078] Furthermore, the acoustic coupler device 100 includes additional silicone tubes 152 and 154, through which the second coupler 140 communicates with the outside of the housing 102 (external air). Specifically, in one silicone tube 152, one end of its opening communicates with the space 146 on the front side of the diaphragm 144a inside the housing 142, and the other end of its opening penetrates the bottom plate 106 of the housing 102 and protrudes downward beyond the lower surface. Similarly, in the other silicone tube 154, one end of its opening communicates with the space 148 on the rear side of the diaphragm 144a inside the housing 142, and the other end of its opening penetrates the bottom plate 106 of the housing 102 and protrudes downward beyond the lower surface. Thus, in the second coupler 140, the front space 146 and the rear space 148, divided by the diaphragm 144a of the speaker unit 144, are respectively connected to the external air.

[0079] [Ventilation through the feet]

[0080] As described above, silicone tubes 152 and 154 penetrate the bottom plate 106 of the housing 102 and protrude downwards from the lower surface. However, at this time, the lower ends of each silicone tube 152 and 154 are open within the corresponding foot 110. Figure 2As shown, a circular ventilation passage 110a is formed inside the foot portion 110, and a through-passage notch 110b is formed radially on a part of the side of the foot portion 110 that serves as a non-supporting surface (a surface not used for support), thereby allowing the ventilation passage 110a to communicate with the outside air through the notch 110b. Therefore, each silicone tube 152, 154 can communicate with the outside air through the ventilation passage 110a and the notch 110b inside the foot portion 110.

[0081] [Structure for Static Pressure Adjustment]

[0082] In this embodiment, static pressure adjustment is performed using silicone tubes 150, 152, and 154 as described below.

[0083] (1) The silicone tube 150 connecting the first coupler 120 and the second coupler 140 connects the space 146 on the front side of the vibrating plate 144a and the space on the outside and inside side of the piezoelectric vibrator 128 (sound guide channel 122d). This is because one end of the silicone tube 150 is connected to the slit 132a of the rubber pad 132.

[0084] (2) Another silicone tube 152 connects the space 146 on the front side of the vibrating plate 144a to the outside air. Thus, the static pressure of the space 146 on the front side is maintained, and the static pressure of the space (sound guide channel 122d) on the outside and inside side of the piezoelectric vibrator 128 is also maintained.

[0085] (3) Other silicone tubes 154 connect the space 148 on the rear side of the vibrating plate 144a to the outside air. Thus, static pressure is also maintained in the space 148 on the rear side.

[0086] (4) According to (1) to (3) above, static pressure adjustment can be performed from the calibration space Sp in the first coupler 120 to the space on the outside and inside of the piezoelectric vibrator 128 (sound guide channel 122d), and then to the space on the front side 146 and the space on the rear side 148 of the vibrating plate 144a in the second coupler 140.

[0087] It should be noted that, as an example, the inner diameter and length of the silicone tube 150 can be set to... Approximately 20cm, as an example, the inner diameter and length of silicone tubes 152 and 154 can be set to... The width is approximately 10cm, but it is not limited to this. In addition, the width, depth, and height of the slit 132a can be set to approximately 4mm, 2mm, and 0.5mm, but it is not limited to this.

[0088] [Vibration Suppression Components]

[0089] An ultra-soft polyurethane 138 for suppressing vibration transmission is sandwiched between the first coupler 120 and the second coupler 140. Besides suppressing vibration transmission from the second coupler 140 to the first coupler 120 during calibration in the low-frequency range, the ultra-soft polyurethane 138 also fixes the position of the first coupler 120. Furthermore, it absorbs, mitigates, and disperses the impact on the first coupler 120 when a reference microphone Ms or a calibrated microphone Mp is inserted from the outside. As an example, the thickness of the ultra-soft polyurethane 138 can be set to approximately 3 mm, but it is not limited to this.

[0090] [Example of calibration method]

[0091] Next, an example will be given to illustrate the calibration method of the acoustic coupler device 100 using this embodiment. It should be noted that the calibration method is not limited to the following example.

[0092] Figure 6 This diagram illustrates a process example of a calibration method using the acoustic coupler device 100. During calibration, a pre-defined external device OD is preferably used. The external device OD can control the drive signals to the piezoelectric vibrator 128 and the speaker unit 144, receive calibration tones, and acquire signals output from each preamplifier PA1 and PA2. Furthermore, it can control the transmission of insertion signals to each microphone Mm and Ms / Mp, and acquire signals output from each preamplifier PA1 and PA2. Moreover, by measuring and storing the input signals transmitted to each microphone Mm and Ms / Mp and the output signals of the preamplifier PA1 and PA2, the free-field sensitivity level or sound pressure level of the calibrated microphone Mp is calculated by appropriately adding the correction values.

[0093] Step S1: First, connect the external device OD to the acoustic coupler device 100. The external device OD can be connected via the connector 113 described above. Furthermore, the inserted preamplifier PA2 can be connected to the external device OD via direct wiring.

[0094] Step S2: Insert the reference microphone Ms into the insertion port 112a of the acoustic coupler device 100, so that the front end of the protective mesh of the reference microphone Ms abuts against the spacer 124b. Then, tighten the knurled knob 112 to secure the reference microphone Ms together with the preamplifier PA2.

[0095] Step S3: The electrical signal, pre-calculated based on the sound pressure sensitivity level of the reference microphone Ms and the calibrated sound pressure level (the sound pressure level output from the piezoelectric vibrator 128 and speaker unit 144 of the acoustic coupler device 100, which are used as sound sources, and set at each frequency in the external device OD), is input from the external device OD to the reference microphone Ms via the preamplifier PA2. The output voltage of the preamplifier PA2 at this time is measured and stored in the external device OD.

[0096] Step S4: Switch the signal line of the external device OD from the preamplifier PA2 to the piezoelectric resonator 128 or the speaker unit 144. Adjust the input signal to the calibration sound source so that the output voltage of the preamplifier PA2 is the same as in the previous step S3, and output the calibration tone. Measure the input voltage to the calibration sound source at this time and store it in the external device OD.

[0097] It should be noted that the frequency range that can be measured at this time is, for example, 1Hz to 20kHz (per 1 / 3 octave). The actual lower and upper frequency limits are set according to the frequency response specifications of the reference microphone Mm or the microphone Mp used for calibration. At this time, the piezoelectric resonator outputs sound from 1kHz to 20kHz, and the speaker unit outputs sound from 1Hz to 800Hz. The calibration sound pressure level is, for example, 104dB from 1Hz to 100Hz and 94dB from 125Hz to 20Hz, but is not limited to these.

[0098] Step S5: Measure the output voltage from preamplifier PA1 at step S4 and store it in external device OD.

[0099] Step S6: Switch the signal line of the external device OD from the piezoelectric resonator 128 or the speaker unit 144 to the preamplifier PA1. Adjust the input signal to the monitoring microphone Mm via the preamplifier PA1 so that the output voltage of the preamplifier PA1 is the same as in the previous step S5. Measure the input voltage at this time and store it in the external device OD.

[0100] Step S7: In steps S3 to S6 up to this point, the sound pressure sensitivity level of the monitoring microphone Mm is determined based on the relationship between the input voltage and output voltage of the preamplifier PA1 at each frequency, and the result is stored in the external device OD.

[0101] Step S8: Remove the reference microphone Ms and replace it with the calibrated microphone Mp. At this point, set the preamplifier PA2 to use the same preamplifier.

[0102] Step S9: From this point onward, perform the same measurements as in steps S3 to S6. However, since the measurement is based on the sound pressure sensitivity level of the monitoring microphone Mm determined in step S7, the measurement process becomes... Figure 6 S6→S5→S4→S3. Based on the relationship between the input voltage and output voltage of the preamplifier PA2 at each frequency, the sound pressure sensitivity level of the microphone Mp being calibrated is determined.

[0103] Step S10: At this time, if the microphone Mp being calibrated is a free-field microphone, the free-field sensitivity level is calculated by adding the free-field sensitivity level - sound pressure level correction amount (free-field correction amount) unique to each microphone.

[0104] Step S11: Then, save the calibration results (free field sensitivity level or sound pressure sensitivity level of the calibrated microphone Mp) and output them from the external device OD.

[0105] By performing the above steps S1 to S11, the microphone Mp to be calibrated can be calibrated.

[0106] The acoustic coupler device 100 according to the above-described embodiment has the following advantages.

[0107] (1) The calibration of a 1 / 2-inch measuring microphone and noise meter can be performed in a wide frequency band of 1 Hz to 20 kHz by a single measurement unit (one acoustic coupler device 100) and by a single measurement.

[0108] (2) In addition, due to the internal structure ( Figure 2 , Figure 3 It has sufficient calibration accuracy and can meet the requirements of Appendix B of IEC61672-1:2013 (JISC1509-1:2017) "Maximum permissible value of measurement uncertainty", namely the maximum permissible value of measurement uncertainty of "frequency weighted characteristic A, frequency weighted characteristic C and frequency weighted characteristic Z".

[0109] (3) The overall shape is small (for example, the outer dimensions of the housing 102). (Approximately 127mm in height and weighing about 1.4kg), the device is easy for the calibration operator to carry, thus enabling calibration operations in any location.

[0110] (4) Both the first coupler 120 corresponding to the high frequency range and the second coupler 140 corresponding to the low frequency range are structures that can be adjusted by static pressure, so they can be stably calibrated in a wide frequency band.

[0111] (5) The outer openings of the silicone tubes 152 and 154 are located inside the foot 110, and the vents are not exposed on the outer surface of the housing 102. Therefore, the vents are inconspicuous and can improve the aesthetics of the product. In addition, the structure can prevent the vents from being blocked by the sealing of certain objects on the bottom surface or by arbitrary labeling, so that static pressure adjustment can always be performed stably.

[0112] (6) Regardless of the model of the inserted reference microphone Ms or the calibrated microphone Mp, it can be used with all hydrostatic adjustment structures and can be calibrated in the low frequency band in the same way as free sound field.

[0113] This invention is not limited to the one embodiment described above and can be implemented in various modifications. The various specifications and values ​​listed in one embodiment are examples as described above and are not limited thereto.

[0114] Furthermore, the shape and structure of the housing 102 and each component are illustrated in the figure as an example, and other arbitrary changes can be made. For example, the housing 102 may not be cylindrical, but prismatic, or the insertion port 112a may be open outside the upper surface.

Claims

1. An acoustic coupler device, comprising: The support member can accommodate the first and second microphones related to calibration internally, with a calibration space formed between their respective protective mesh front faces; A first sound source, disposed on the outside of the supporting member, generates a first calibration tone related to calibration in a first frequency band; The second sound source is positioned on the outside of the support member at a different location than the first sound source, and generates a second calibration tone related to calibration in a second frequency band different from the first frequency band as the vibrating plate is driven. A connecting path is provided so that the front and rear spaces, divided by the vibrating plate of the second sound source, are connected to the outside air, respectively. The first sound guide channel connects the outer side of the support member with the calibration space, enabling the first calibration sound from the first sound source to be introduced into the calibration space. as well as The second sound guide channel connects the first sound guide channel to the front space defined by the vibrating plate of the second sound source on the outside of the support member. It allows the second calibration tone to be guided into the calibration space through the first sound guide channel, and also connects the calibration space to the outside air through the connecting path. The first microphone is a microphone built into the acoustic coupler device, and the second microphone is a microphone inserted into the acoustic coupler device.

2. The acoustic coupler device according to claim 1, characterized in that, The support member has: The cylindrical body has inner wall surfaces surrounding the sides of the first microphone and the second microphone; The first sealing member seals the gap between the inner wall surface of the main body and the side of each protective mesh of the first microphone and the second microphone at the position between the front end and the rear end of each protective mesh to achieve airtightness. The second sealing member seals the gap between the side of the preamplifier connected to the first microphone and the second microphone respectively and the inner wall of the main body at the position between the first sealing member and the outside air to achieve airtightness. as well as Multiple ventilation paths are provided, such that the gap between the side of one of the first microphones and the second microphone and the inner wall of the body is connected to the outside of the body at the positions between the front end face of the protective mesh and the first sealing member and between the first sealing member and the second sealing member, respectively.

3. The acoustic coupler device according to claim 1, characterized in that, The first sound source has a cylindrical piezoelectric vibrator arranged to surround the support member, which generates the first calibration tone by means of radial vibration of the piezoelectric vibrator. The piezoelectric vibrator is held in place by a vibration damper that suppresses the transmission of vibration to the support member.

4. The acoustic coupler device according to claim 3, characterized in that, The vibration damping element is positioned at both ends of the piezoelectric vibrator, maintaining the circular shape of the piezoelectric vibrator. The second sound channel connects the first sound channel with the space on the front side divided by the vibrating plate, in a state where the outer side of the piezoelectric vibrator is connected to the inner side through a slit formed in a portion of the circumference of the annular vibration damper.

5. The acoustic coupler device according to any one of claims 1 to 4, characterized in that, The support member is housed within a container that surrounds the support member and the first sound source on the outside. The container has a sound-absorbing element that absorbs the first calibration sound outside the first sound source.

6. The acoustic coupler device according to any one of claims 1 to 4, characterized in that, It also has: A vibration suppression component, disposed between the first sound source and the second sound source, is capable of suppressing the transmission of vibration from the second sound source to the support component accompanying the generation of the second calibration tone.

7. The acoustic coupler device according to any one of claims 1 to 4, characterized in that, It also has: A housing that at least accommodates the support member, the first sound source, and the second sound source internally; and Feet are provided on the lower surface of the housing so that the housing can be placed while maintaining the housing in a predetermined posture. The connecting passage connects to the outside air from the inside of the housing through the non-mounted surface of the foot.

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