Variable operating condition acoustic test chamber and test platform

Abstract

This invention provides a variable-condition acoustic experimental chamber and platform. The variable-condition acoustic experimental chamber includes: a fixed chamber, which is hollow and open on one side; an inner flange structure, extending radially outward from the edge of the opening side of the fixed chamber, with N flange fixing structures arranged circumferentially, where N≥4; and a detachable condition plate, the outer contour of which matches the shape of the inner flange structure, with condition plate fixing structures arranged circumferentially to match the N flange fixing structures. The detachable condition plate is detachably fastened to the opening side of the fixed chamber through the cooperation of the N flange fixing structures and the N condition plate fixing structures, thus enclosing an acoustic experimental space between the fixed chamber and the detachable condition plate. This invention allows for the selection of different condition plates based on the required conditions, facilitating disassembly and assembly, and enabling simpler and more cost-effective changes to experimental conditions.

Description

Technical Field

[0001] This invention relates to the field of noise and vibration control services in the advanced environmental protection industry, and particularly to a variable-condition acoustic test chamber and test platform. Background Technology

[0002] In the field of engineering noise reduction services, we face many complex simulations. Sometimes noise reduction is needed in enclosed indoor environments, and sometimes sound wave transmission needs to be blocked in open environments such as playgrounds. Therefore, to reduce noise propagation in various complex environments, it is necessary to build an acoustic experimental platform in the laboratory to experimentally verify various noise reduction materials so that they can be applied to real engineering environments. However, existing acoustic experimental chambers cannot meet the simulation requirements of various working conditions. Summary of the Invention

[0003] (a) Technical problems to be solved

[0004] The technical problem this invention aims to solve is to provide an acoustic experimental platform with variable operating conditions, simulating different real acoustic environments, addressing the inconvenience of changing operating environment conditions during experiments, increasing the diversity of measurement functions on the experimental platform, and further enabling experimental verification of the properties of acoustic materials in a three-dimensional sound field. This invention expects to at least partially solve one of the aforementioned technical problems.

[0005] (II) Technical Solution

[0006] In a first aspect, this invention provides a variable-condition acoustic test chamber for use in variable-condition environments. The acoustic test chamber includes: a fixed chamber, which is hollow and open on one side; an inner flange structure, exhibiting a flange shape extending radially outward from the edge of the opening side of the fixed chamber, with N flange fixing structures arranged circumferentially, where N≥4; and a detachable condition plate, the outer contour of which matches the shape of the inner flange structure, with condition plate fixing structures arranged circumferentially to match the N flange fixing structures; wherein, through the cooperation of the N flange fixing structures and the N condition plate fixing structures, the detachable condition plate is detachably fastened to the opening side of the fixed chamber, enclosing an acoustic test space between the fixed chamber and the detachable condition plate.

[0007] Specifically, the acoustic experimental chamber of this invention includes: a detachable acrylic sheet, five fixed empty boxes for fixed connection, a flange plate, a ventilated sound insulation plate, an elastic aluminum plate, a micro-perforated plate, a measuring microphone, a reference microphone, a speaker, a microphone holder base, a holder positioning rod, and a microphone holder sleeve. The flange plate has bolt through holes identical to those on the detachable working plate, and its dimensions are the same as those of the detachable single plate and the elastic plate. The flange plate is designed with a hollow center, the same size as the YZ plane of the cavity.

[0008] Furthermore, the five panels were rigidly connected and made non-removable, with a wall thickness of 20cm to improve the rigidity of the panels and prevent sound leakage. Acrylic panels were also chosen as the overall material for the panels to ensure the visibility of the experiment.

[0009] Furthermore, the working condition was selected under a closed test. Based on parameters such as the size of the flange and the weight of the total box, the diameter of the connecting bolt through hole was selected to be 8mm, the thickness of the flange was 10mm, there were 8 bolt holes on each of the upper and lower long sides, and 6 bolts on each of the left and right short sides for fixed connection.

[0010] Furthermore, to ensure the airtightness of the sealed experiment, plastic sealing rings with the same geometric dimensions as the flange plate were added to the bolt connections. These sealing rings also had bolt holes of the same position and size to prevent sound leakage. For the five through-holes around the enclosure, rigid nylon material was selected and designed as 10mm diameter cylinders. Unused through-holes were inserted during the experiment to further ensure airtightness. The through-holes used in the experiment (containing data cables connecting to the microphone / speaker) were plugged with convex rubber blocks to ensure a tight seal.

[0011] Furthermore, to verify the enclosure's airtightness, a speaker was placed inside the fully enclosed enclosure, and a random white signal sound was played. A microphone was used to measure the sound pressure level at a point outside the enclosure in both cases: no sound was played and sound was played. The microphone's positioning was determined by the microphone holder base, the holder positioning rod, and the microphone mounting sleeve. The microphone's position in the XY direction could be determined by moving the base, and its position in the Z direction could be determined by moving the mounting sleeve on the positioning rod.

[0012] In a second aspect, the present invention provides a variable-condition acoustic experimental platform for use in variable-condition environments. This platform includes: a truss platform; a variable-condition acoustic experimental chamber as described above, wherein the bottom surface of the fixed chamber is mounted on the truss platform, and the lower part of the inner flange structure is suspended through the crossbeam of the truss platform; a loudspeaker disposed within the acoustic experimental space; a microphone disposed in front of the loudspeaker within the acoustic experimental space and fixed by a microphone holder; and a signal output and acquisition system disposed outside the fixed chamber, electrically connected to the loudspeaker and the microphone, for controlling the loudspeaker output and acquiring and processing the signal obtained by the microphone.

[0013] Specifically, the variable-condition acoustic experimental platform of this invention includes: the variable-condition acoustic experimental box as described above, with a total weight of 23.05 kg, a truss platform, and a signal output and acquisition system. Therefore, the experimental box is placed on a truss experimental platform with a height of 1.5 meters, and a 20 mm thick experimental truss is placed at the bottom of the box as a pad to prevent deformation of the flanges under stress. The measurement system used in this experiment is a LabVIEW data processing program, which integrates data output and signal acquisition. One output is a loudspeaker, playing random white noise signals. The other acquisition is a microphone, acquiring sound pressure signals at selected spatial points. The processing function of this measurement system is to acquire real-time sound pressure signals, use Fourier transform to convert the time-domain signal into a frequency signal, and perform averaging processing during acquisition to form the final steady-state signal data of the sound field.

[0014] Furthermore, to change from a closed working condition to a ventilated and soundproof working condition, the removable panel needs to be replaced with a ventilated and soundproof panel. This panel consists of a ventilation structure, and its four sides are still designed with bolt holes. The panel is fixed to the enclosure with bolts, thus realizing the transformation from a closed working condition to a ventilated and soundproof working condition.

[0015] Furthermore, to change the enclosed working condition into an acoustic-vibration coupling system, the detachable plate needs to be replaced with an elastic plate of the same size and fixed to the enclosure by bolts.

[0016] (III) Beneficial Effects

[0017] As can be seen from the above technical solution, the present invention has at least one of the following beneficial effects compared to the prior art:

[0018] (1) Set up a detachable working condition plate connected to the fixed box. Select different working condition plates based on the required working conditions. Disassembly and assembly are convenient, and the experimental working conditions can be changed more easily and cost-effectively.

[0019] (2) The detachable working condition plate and the fixed box are fixed by bolt-nut structure, and the detachable working condition plate and the fixed box are sealed by elastic sealing ring. The structure is simpler and more convenient, and the cost is reduced as much as possible.

[0020] (3) The bottom surface of the acoustic experimental space is provided with printed or engraved planar coordinates; the positioning rod of the fixation device is provided with printed or engraved longitudinal coordinates, so that the three-dimensional coordinates of the microphone can be conveniently and accurately positioned, thus improving the accuracy of the experiment.

[0021] (4) Several sets of fixed slots are set along the longitudinal direction of the acoustic experimental space to place various sound-absorbing materials or metamaterials, so as to directly study the performance of the materials, or to study the effect of the materials on the sound field after they are placed.

[0022] (5) The loudspeaker can be placed at any position required for the experiment. The microphones are divided into a reference microphone and a measuring microphone. The reference microphone is placed very close to the loudspeaker to normalize the sound pressure measurement and reduce the sound pressure error caused by the air path. The measuring microphone measures the sound pressure at real spatial points. The introduction of two microphones improves the measurement accuracy.

[0023] (6) The variable working condition acoustic test box is set up on the truss platform. The lower part of the inner flange structure passes through the crossbeam of the truss platform and is suspended in the air. On the one hand, the vibration reduction performance is guaranteed, and on the other hand, the weight of the box is avoided from pressing on the inner flange structure. Attached Figure Description

[0024] Figure 1A , Figure 1B , Figure 1C These are schematic diagrams of the variable-condition acoustic test chamber according to embodiments of the present invention under closed conditions, ventilated and sound-insulating conditions, and acoustic-vibration coupling conditions.

[0025] Figure 2A and Figure 2B These are open views of the internal structure of the variable-condition acoustic test chamber according to an embodiment of the present invention from different angles.

[0026] Figure 3 This is a schematic diagram of the ventilation and sound insulation panel in the variable working condition acoustic test chamber of this invention.

[0027] Figure 4 This is a schematic diagram of the microphone holder in the variable working condition acoustic test chamber according to an embodiment of the present invention.

[0028] Figure 5 This is a schematic diagram of the hardware components of the variable working condition acoustic experimental platform in a closed working condition according to an embodiment of the present invention;

[0029] Figure 6 This is a schematic diagram of the variable working condition acoustic experimental platform in a closed working condition according to an embodiment of the present invention.

[0030] Figure 7 and Figure 8 These are schematic diagrams of the hardware components of the variable-condition acoustic experimental platform according to embodiments of the present invention under ventilation and sound insulation conditions and acoustic-vibration coupling conditions. Detailed Implementation

[0031] The inventive concept of this invention lies in providing an acoustic experimental platform with variable operating conditions through a detachable operating condition board, simulating different real acoustic environments, solving the inconvenience of variable operating environment conditions during the experiment and adding diversity to the measurement functions of the experimental platform.

[0032] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0033] According to a first aspect of the present invention, a variable-condition acoustic experimental chamber is provided. This chamber enables the verification of artificially designed metamaterials, the manipulation of sound waves in a three-dimensional sound field, and the exploration of noise reduction in the internal sound field.

[0034] Figure 1A , Figure 1B , Figure 1C These are schematic diagrams of the variable-condition acoustic test chamber according to embodiments of the present invention under closed, ventilated sound insulation, and acoustic-vibration coupling conditions. Please refer to... Figures 1A to 1C The variable-condition acoustic test chamber in this embodiment includes:

[0035] Fixed box 10, which is hollow and has an opening on one side;

[0036] The inner flange structure 20 has a flange shape that extends radially outward from the edge of the fixed box opening side, and N flange fixing structures 21 are provided in the circumferential direction, where N≥4;

[0037] The detachable working condition plate has an outer contour that matches the shape of the inner flange structure, and a working condition plate fixing structure 31 that matches N flange fixing structures is provided in its circumferential direction.

[0038] Among them, through the cooperation of N flange fixing structures and N working condition plate fixing structures, the detachable working condition plate can be detachably fastened to the opening side of the fixed box, thus creating an acoustic experimental space between the fixed box and the detachable working condition plate.

[0039] The following is a detailed description of each component of the variable operating condition acoustic test chamber in this embodiment.

[0040] In this embodiment, the fixed enclosure 10 is a cuboid shape formed by fixing and splicing five rigid plates together, and the corresponding acoustic experimental space A is also cuboid in shape. For the sake of experimental visibility, the five rigid plates are single acrylic sheets with a wall thickness of 2mm. They are rigidly connected and cannot be disassembled, which increases the rigidity of the plates and prevents sound leakage.

[0041] Specifically, the fixed enclosure is constructed from five acrylic panels, with the sixth side designed as an open shape. The acoustic experimental space inside the enclosure measures 0.49m * 0.32m * 0.25m. Using the simulation software Comsol, it was determined that there are 22 characteristic frequencies below 1400Hz within the internal cavity of the enclosure, which is sufficient to meet the experimental measurement requirements.

[0042] It should be noted that although the fixed enclosure in this embodiment is rectangular, the present invention is not limited thereto. In other embodiments of the present invention, fixed enclosures of different shapes can be designed according to the needs of the acoustic experimental space. As long as different testing environments can be achieved by changing the test conditions board, they are all within the protection scope of the present invention.

[0043] This embodiment also includes several sets of fixing slots 11 arranged along the depth of the acoustic experimental space for fixing test materials. Through these fixing slots, various sound-absorbing materials or designed metamaterials can be placed within the acoustic experimental space to directly study the material's performance, or to study the effect of the placed material on the sound field. This increases the reliability of the experiment, improves the success rate of three-dimensional sound field experiments, and reduces space usage and labor intensity.

[0044] Figure 2A and Figure 2B These are open views of the internal structure of the variable-condition acoustic test chamber according to an embodiment of the present invention, taken from different angles. Please refer to... Figure 2A and Figure 2B The inner flange structure is an independent flange plate fixed to the opening side of the fixed box, and its radial inner side forms a flange plate opening that matches the opening of the fixed box.

[0045] It should be noted that although this embodiment features an inner flange structure independent of the fixed housing, the present invention is not limited thereto. In other embodiments of the present invention, the inner flange structure may also be a flange portion formed by extending radially outward from the opening side of the fixed housing, and this flange portion is an integral structure with the fixed housing. Such a structure is also within the protection scope of the present invention.

[0046] In this embodiment, different detachable working condition plates can be replaced as needed. Both the flange plate and the detachable working condition plate are rectangular plates with identical outer contours. This embodiment of the variable working condition acoustic test chamber includes: a blind plate 32 and two different detachable working condition plates, used to achieve different working condition testing environments.

[0047] Blind flange 32 is used to simulate enclosed working conditions, such as... Figure 1A As shown. The blind plate 32 is a 20mm thick acrylic plate with spiral through holes around its perimeter, allowing it to be fixed to the flange plate. The blind plate 32 is designed to conform to hard boundaries, prevent sound leakage, and improve visibility.

[0048] The detachable working condition panel consists of a ventilation and sound insulation panel 33 and an elastic panel 34. The detachable working condition panel is a split structure, including: an outer flange panel 35, which matches the shape of the inner flange structure, and has working condition panel fixing structures that match N flange fixing structures in the circumferential direction, with an opening on the inner side that is the same as the opening on one side of the fixed box; and a working condition simulation structure, which is set at the opening position of the outer frame structure and sandwiched between the inner flange structure and the outer flange panel.

[0049] The outer flange plate 35 is a unique structure for ventilation and sound insulation applications and for elastic plate applications. It has the same structure as the inner flange structure, but its function is different. Its function is to simulate the gap between the structure and the flange plate by using bolted connections to tighten the structure, thereby enhancing the sealing performance. For example, in 1B, the ventilation and sound insulation structure forms a complete boltable functional plate in the middle of the flange plate. Figure 1C In the middle, the inner flange structure and the outer flange plate 35 are elastic structures.

[0050] Ventilation and sound insulation panel 33 is used to simulate ventilation and sound insulation conditions, such as Figure 1B As shown. Figure 3 This is a schematic diagram of the ventilation and sound insulation panel in the variable-condition acoustic test chamber according to an embodiment of the present invention. Figure 1B and Figure 3 As shown, the ventilation and sound insulation panel 33 includes: an outer flange plate, matching the shape of the inner flange structure, with a working condition plate fixing structure matching the N flange fixing structures on its circumference, and an opening on its inner side identical to the single-sided opening of the fixed box; and a ventilation and sound insulation structure, located at the opening of the outer frame structure, sandwiched between the inner flange structure and the outer flange plate. The ventilation and sound insulation structure further includes: a detachable perforated plate and six spiral structures. The outer flange plate is a thicker flange plate.

[0051] Based on this, the ventilation and sound insulation panel 33 comprises: a relatively thick outer flange plate, a detachable perforated plate, and six spiral structures. The parameters of the spiral structures can be designed independently, with the spiral angle and structural thickness determined according to the required frequency band parameters. Bolt holes are designed on all four sides of the outer flange plate, allowing the ventilation and sound insulation panel to be fixed to the inner flange structure using bolts, thus simulating the ventilation and sound insulation working conditions.

[0052] Those skilled in the art should understand that ventilation and sound insulation structures can have other structures besides the spiral structure. Therefore, the detachable perforated plate can be directly replaced with another structural arrangement, which is also within the scope of protection of this invention.

[0053] Please refer to Figure 1CThe elastic plate 34 is used to simulate acoustic-vibration coupling conditions. The elastic plate 34 includes: an outer flange plate, which matches the shape of the inner flange structure, and has a working condition plate fixing structure that matches the N flange fixing structures in the circumferential direction, and has an opening on the inner side that is the same as the opening on one side of the fixing box; and an elastic structure, which is set at the opening position of the outer frame structure and sandwiched between the inner flange structure and the outer flange plate.

[0054] The outer flange plate is a 2mm / 5mm thick aluminum alloy plate with bolt holes around its perimeter for fixing to the flange plate. This design also prevents sound leakage between the bolt holes of the elastic plate. Another flange plate is then fixed externally, forming a "flange plate-elastic structure-flange plate" structure.

[0055] In this invention, a detachable working condition plate is provided that is connected to the fixed box. Different working condition plates can be selected based on the required working conditions. Disassembly and assembly are convenient, and the experimental working conditions can be changed more easily and cost-effectively.

[0056] In this embodiment, the flange fixing structure 21 is a flange bolt through hole; the working condition plate fixing structure 31 is a working condition plate bolt through hole; the flange bolt through hole 21 and the working condition plate bolt through hole 31 are evenly distributed in the circumferential direction of the inner flange structure; N connecting bolts pass through the corresponding flange bolt through hole and working condition plate bolt through hole respectively and are fixed, thereby detachably fixing the detachable working condition plate to the opening side of the fixed box.

[0057] Specifically, the flange plate is 10mm thick, with 8 bolt holes on each of the top and bottom long sides and 6 bolt holes on each of the left and right short sides. The holes are 8mm in size and symmetrically distributed on both sides. To better assemble the bolts and bolt holes, bolts and nuts with a pitch diameter of 6mm are selected. Furthermore, to prevent loosening at the connection, washers of the same size as the flange plate are selected to enhance friction.

[0058] In this invention, the detachable working condition plate and the fixed housing are fixed by a bolt-nut structure, and the detachable working condition plate and the fixed housing are sealed by an elastic sealing ring. The structure is simpler and more convenient, and the cost is reduced as much as possible.

[0059] Those skilled in the art should understand that although this embodiment uses a bolt and nut method, the present invention is not limited thereto. In other embodiments of the present invention, other methods can be used to fix the detachable working plate to the inner flange structure, such as various forms of clips.

[0060] Furthermore, to achieve reliable sealing and fixation, a plastic sealing ring 22 is provided between the inner flange structure and the removable working plate. The plastic sealing ring 22 has the same geometric dimensions as the flange plate, and has bolt holes of the same position and size on it to prevent sound leakage.

[0061] In this embodiment, the fixed housing has K through holes for cables to pass through, where K ≥ 2. When no cable passes through, the through holes are sealed with a rigid material; when a cable passes through, the through holes are sealed with an elastic material.

[0062] Specifically, for the five through-holes around the enclosure, a rigid nylon material was selected and designed as 10mm diameter cylinders. Unused through-holes were inserted during the experiment to further ensure airtightness. The through-holes used in the experiment (containing data cables connecting the microphone / speaker) were plugged with convex rubber blocks to ensure a tight seal. This invention allows the speaker and microphone to be placed inside the enclosure, with their respective data cables connected to the operating system's ports through the enclosure; therefore, the placement of the speaker and microphone can be arbitrarily chosen.

[0063] In this embodiment, the acoustic experimental space A is rectangular in shape, and its bottom surface is provided with printed or engraved planar coordinate scales; the variable working condition acoustic experimental box also includes: two microphone holders 40, which are set in the acoustic experimental space.

[0064] Figure 4 This is a schematic diagram of the microphone holder in the variable-condition acoustic test chamber according to an embodiment of the present invention. Figure 4 As shown, the microphone holder includes: a holder base 41; a holder positioning rod 41 fixed to the holder base and vertically upward; and a microphone fixing sleeve 42 movably fixed at a preset height on the holder positioning rod. One end of the microphone fixing sleeve 42 is fixed to the rod, and the other end fits around a cylindrical microphone. The sleeve can move up and down, and the lower holder base can move the entire assembly forward, backward, left, and right, thereby controlling six degrees of freedom. The holder positioning rod has printed or engraved longitudinal scale coordinates.

[0065] In this invention, the bottom surface of the acoustic experimental space is provided with printed or engraved planar coordinate scales; the positioning rod of the fixture is provided with printed or engraved longitudinal coordinate scales, thereby facilitating and accurately positioning the three-dimensional coordinates of the microphone and improving the accuracy of the experiment.

[0066] Based on the above-mentioned variable-condition acoustic experimental chamber, the present invention also provides a variable-condition acoustic platform. Figure 5 This is a schematic diagram of the hardware components of the variable working condition acoustic experimental platform in a closed working condition according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the variable working condition acoustic experimental platform in a closed working condition according to an embodiment of the present invention. Figure 7 and Figure 8 These are schematic diagrams of the hardware components of the variable-condition acoustic experimental platform according to embodiments of the present invention under ventilation and sound insulation conditions and acoustic-vibration coupling conditions.

[0067] Please combine Figure 2A , Figure 2B , Figures 5-8The variable-condition acoustic experimental platform in this embodiment includes:

[0068] Truss platform 50;

[0069] The variable working condition acoustic test chamber has its bottom surface fixed on the truss platform, with the lower parts of the inner flange structure and the outer flange plate suspended through the crossbeam of the truss platform.

[0070] Speaker 61 is installed in acoustic experimental space A.

[0071] The microphone is positioned in front of the speaker within the acoustic experimental space and is secured by a microphone holder.

[0072] The signal output and acquisition system 80 is located on the outside of the fixed enclosure and is electrically connected to the speaker and microphone. It is used to control the speaker output and acquire and process the signal obtained by the microphone.

[0073] In this embodiment, the total weight of the variable working condition acoustic test box is 23.05Kg, and there are 25mm flanges around the single board. Therefore, the test box is placed on a truss test platform with a height of 1.5 meters, and a 20mm thick test truss is placed at the bottom of the box as a pad to prevent the flanges from deforming under stress.

[0074] In this invention, the variable working condition acoustic test chamber is mounted on a truss platform, with the lower parts of the inner flange structure and the outer flange plate suspended through the crossbeam of the truss platform. This ensures vibration reduction performance on the one hand, and avoids the pressure of the chamber weight on the inner flange structure and the outer flange plate on the other.

[0075] A loudspeaker 61 and a microphone are installed in the acoustic experimental space. The loudspeaker 61 is used to play sound wave signals. The loudspeaker can be placed at any position required during the experiment. The microphone is divided into a reference microphone 71 and a measuring microphone 72. The reference microphone 71 is placed very close to the loudspeaker and is mainly used to normalize the sound pressure measurement and reduce the sound pressure error caused by the air path. The measuring microphone 72 measures the sound pressure at a real spatial point.

[0076] The external speaker cable can be connected to the signal acquisition system interface 19 through a through-hole in the enclosure wall, and the data cable is secured with tape. The speaker and microphone are fixed inside the enclosure by a microphone holder. The microphone cable is also connected to the signal output and acquisition system interface through a cable pass-through hole in the enclosure wall.

[0077] Please refer to Figure 5 and Figure 6 To verify the sealing performance of the enclosure, a speaker 61 was placed inside the enclosure under fully enclosed conditions, and a random white signal sound was played. The sound pressure signal at a point outside the enclosure was measured using a measuring microphone in both cases: when no sound was played and when sound was played.

[0078] Please refer to Figure 3 and Figure 7 To change from a closed working condition to a ventilated and soundproof working condition, the removable panel needs to be replaced with a ventilated and soundproof panel. This panel consists of a ventilation structure, and its four sides are still designed with bolt holes. By fixing the panel to the enclosure with bolts, the transformation from a closed working condition to a ventilated and soundproof working condition is achieved.

[0079] Please refer to Figure 8 To change the closed-loop configuration to an acoustic-vibration coupling system, the detachable plate needs to be replaced with an elastic plate of the same size. The elastic plate is a 2mm / 5mm thick aluminum alloy plate with bolt holes around its perimeter for fixing to the flange plate. To prevent sound leakage between the bolt holes, another flange plate is then fixed externally, forming a "flange plate-elastic plate-flange plate" structure.

[0080] The signal output and acquisition system 80 is a LabVIEW data processing program that integrates data output and signal acquisition. One output is a speaker playing random white noise; the other acquisition is a microphone acquiring sound pressure levels at selected spatial points. The system's processing function is to acquire real-time sound pressure signals, convert the time-domain signal into a frequency signal using Fourier transform, and perform averaging during acquisition to form the final steady-state sound field signal data. Compared to traditional testing methods, this invention reduces the number of speakers and microphones required.

[0081] In the signal output and acquisition system, the front and rear panels are programmed by integrated hardware within the software, with a frequency acquisition step size of 2Hz and acquisition limits of 0-5000Hz. It includes filtering, timing, and looping systems to accurately output a composite white noise signal and acquire the sound pressure level (SPL) signal at the measurement microphone's spatial point in real time. Finally, after forming a steady-state sound field within the enclosure, the steady-state complex SPL at that point is analyzed. During measurement, the speaker emits white noise excitation according to program instructions, while a reference microphone is fixed in front of the speaker, and the measurement microphone is fixed at the selected measurement point to measure the real-time signal. After Fourier transform, the average SPL signal of the steady-state sound field is output. The output signal data is directly saved as a txt file by the system.

[0082] Within the acoustic environment of this experimental platform, the acoustic environment of a completely empty enclosure can be directly measured. Alternatively, complex acoustic noise reduction materials, such as porous sound-absorbing materials and Helmholtz resonant materials, can be added. Taking the placement of a micro-perforated panel as an example... Figure 2A and Figure 2B As shown, the fixing slots 11 inside the fixed housing hold the micro-perforated plate 91 at its four edges, forming impedance boundaries. The impedance value of the micro-perforated plate can be theoretically expressed as:

[0083] Z mpp=R m +jωX m

[0084]

[0085]

[0086] R m =ρcr m

[0087] X m =ρcx m

[0088] in, η is the kinematic viscosity coefficient, t is the air viscosity coefficient, σ is the thickness of the micro-perforated plate, c is the perforation rate of the micro-perforated plate, and d is the pore diameter of the micro-perforated plate.

[0089] In experimental verification, the measured impedance value of the microperforated plate was:

[0090]

[0091] Δp is the sound pressure difference between the two sides of the micro-perforated plate, and Δv is the difference in normal velocity of particles on both sides of the plate. These values ​​can be obtained by measuring two microphones.

[0092] The elastic plate 34 is fixed to the box body by bolts. On the truss platform outside the box body, the motor is fixed to the experimental platform by the cooperation of the truss and the flathead screw. The rotation of the motor drives the rotation of the cross buckle to hit the elastic plate, thereby solving the excitation problem in the acoustic-vibration coupling system.

[0093] The present invention includes an experimental box, a truss platform, and a signal output and acquisition system. Its innovation lies in the ability to change experimental conditions more easily and cost-effectively. The change of experimental conditions can be achieved simply by disassembling and replacing the detachable condition plate with the corresponding plate required for the condition. At the same time, it also has the advantages of safe and simple assembly and high experimental requirements.

[0094] This concludes the description of the various embodiments of the present invention. Based on the above description, those skilled in the art should have a clear understanding of the present invention.

[0095] It should be noted that the directional terms mentioned in the embodiments, such as "up," "down," "front," "back," "left," "right," "inner," and "outer," are only for reference to the directions in the accompanying drawings and are not intended to limit the scope of protection of the present invention. Throughout the accompanying drawings, the same elements are represented by the same or similar reference numerals. Furthermore, the shapes and dimensions of the components in the drawings do not reflect their actual size and proportions, but are only intended to illustrate the content of the embodiments of the present invention.

[0096] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0097] Those skilled in the art will understand that in the claims and specification of this invention, the word "comprising" does not exclude the presence of elements not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

[0098] For certain implementations, if they are not key aspects of the present invention and are well-known to those skilled in the art, they have not been described in detail in the accompanying drawings or text due to space limitations. In such cases, reference can be made to relevant prior art for understanding. Furthermore, the purpose of providing the above embodiments is merely to ensure that the present invention meets legal requirements. The present invention can be implemented in many different forms and should not be construed as limited to the embodiments described herein. Moreover, the above definitions of elements and methods are not limited to the various specific structures, shapes, or methods mentioned in the embodiments, and those skilled in the art can make simple modifications or substitutions.

[0099] Similarly, it should be understood that, for the sake of brevity, in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof. However, this method of invention should not be construed as reflecting an intention that the claimed invention requires more features than expressly recited in each claim. Rather, as reflected in the claims, the various inventive aspects consist of fewer than all the features of the preceding single embodiment. Furthermore, embodiments may be used in combination with each other or with other embodiments based on design and reliability considerations; that is, technical features from different embodiments can be freely combined to form more embodiments. Therefore, the claims following the detailed description are hereby expressly incorporated into this detailed description, wherein each claim itself is a separate embodiment of the invention.

[0100] The above specific embodiments have provided a detailed description of the purpose, technical means, and beneficial effects of the present invention. It should be understood that the purpose of the detailed description is to enable those skilled in the art to better understand the present invention, and it is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A variable-condition acoustic experimental chamber, characterized in that, include: A fixed enclosure, hollow with an opening on one side; The inner flange structure presents a flange shape that extends radially outward from the edge of the fixed box opening side, and has N flange fixing structures in the circumferential direction, where N≥4; The detachable working condition plate has an outer contour that matches the shape of the inner flange structure, and a working condition plate fixing structure that matches the N flange fixing structures is provided in its circumferential direction. In this configuration, the N flange fixing structures cooperate with the N working condition plate fixing structures, and the detachable working condition plate is detachably fastened to the opening side of the fixed box, thereby enclosing an acoustic experimental space between the fixed box and the detachable working condition plate.

2. The variable-condition acoustic test chamber according to claim 1, characterized in that, The detachable working condition board is a split structure, including: The outer flange plate matches the shape of the inner flange structure, and its circumferential direction is provided with a working condition plate fixing structure that matches the N flange fixing structures. The inner side presents an opening that is the same as the single-sided opening of the fixing box. The working condition simulation structure is set at the opening of the outer frame structure and sandwiched between the inner flange structure and the outer flange plate; The N working condition plates are fixed on the outer flange plate.

3. The variable-condition acoustic test chamber according to claim 2, characterized in that, It also includes: a blind flange, which is closed and fastened to a single-sided opening of the fixed housing; The detachable working condition panel includes one or more of the following: a ventilation and sound insulation panel, whose working condition simulation structure is a ventilation and sound insulation structure; an elastic panel, whose working condition simulation structure is an elastic structure, wherein multiple detachable working condition panels share the outer flange panel.

4. The variable-condition acoustic test chamber according to claim 1, characterized in that, The inner flange structure is a flange portion that extends radially outward from the opening side of the fixed box body, and the flange portion is an integral structure with the fixed box body; The inner flange structure is an independent flange plate fixed to the opening side of the fixed box, and its radially inner side forms a flange plate opening that matches the opening of the fixed box.

5. The variable-condition acoustic test chamber according to claim 4, characterized in that, The fixed box is a cuboid shape formed by fixing and splicing five rigid plates; The inner flange structure is a flange plate; Both the flange plate and the detachable working plate are rectangular plates, and their outer contours are the same.

6. The variable-condition acoustic test chamber according to claim 5, characterized in that, The flange fixing structure is a flange bolt through hole; The working condition board fixing structure is a working condition board bolt through hole; The flange bolt through holes and the industrial control board bolt through holes are evenly distributed in the circumferential direction of the inner flange structure; It also includes: an elastic sealing ring, which is shaped to match the inner flange structure, sandwiched between the inner flange structure and the detachable working plate, and has a sealing ring bolt through hole corresponding to the inner flange structure; N connecting bolts pass through the corresponding flange bolt through holes, sealing ring bolt through holes, and working condition plate bolt through holes and are fixed, thereby detachably fixing the detachable working condition plate to the opening side of the fixed box; washers are provided at the screw positions of the connecting bolts and the corresponding nuts.

7. The variable-condition acoustic test chamber according to claim 1, characterized in that, The acoustic experimental space is rectangular in shape, and its bottom surface is provided with printed or engraved planar coordinate scale. It also includes: K microphone holders, set in the acoustic experimental space, where K≥1. Each microphone holder includes: a holder base; a holder positioning rod fixed to the holder base and vertically upward; and a microphone fixing sleeve movably fixed at a preset height to the holder positioning rod. The holder positioning rod is provided with printed or engraved longitudinal scale coordinates.

8. The variable-condition acoustic test chamber according to claim 1, characterized in that, It also includes: several sets of fixing slots arranged along the depth of the acoustic experimental space for fixing test materials; and / or The fixed housing has K through holes for cables to pass through, where K ≥ 2; wherein, when no cable passes through, the through holes are sealed with a rigid material; when a cable passes through, the through holes are sealed with an elastic material; and / or The thickness of the fixed housing is between 15cm and 30cm, and the thickness of the inner flange structure is between 5mm and 20mm; and / or The acoustic experimental chamber simulates either a ventilation and sound insulation condition or an acoustic-vibration coupling condition. In the ventilation and sound insulation condition, the detachable test panel is a ventilation and sound insulation panel; in the acoustic-vibration coupling condition, the detachable test panel is an elastic plate. A motor rotates, causing a cross-shaped latch to rotate and engage with the elastic plate, thus exciting the acoustic-vibration coupling system. And / or Both the fixed housing and the inner flange structure are made of acrylic.

9. A variable-condition acoustic experimental platform, characterized in that, include: Truss platform; The variable working condition acoustic test chamber as described in any one of claims 1 to 8, wherein the bottom surface of the fixed chamber is mounted on the truss platform, and the lower part of the inner flange structure is suspended through the crossbeam of the truss platform; Loudspeakers are installed within the acoustic experimental space; The microphone is positioned in front of the speaker within the acoustic experimental space and is secured by a microphone holder. The signal output and acquisition system is located on the outside of the fixed enclosure and is electrically connected to the speaker and microphone. It is used to control the speaker output and acquire and process the signal obtained by the microphone.

10. The variable-condition acoustic experimental platform according to claim 9, characterized in that, The signal output and acquisition system uses LabVIEW data processing software for processing. and / or The microphone includes a reference microphone and a measuring microphone, which are respectively connected to the signal output and acquisition system. The reference microphone is used to normalize the sound pressure measurement, and the measuring microphone is used to measure the sound pressure at a real spatial point.

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