Multi-cavity sensing structure for enhancing sound signals

Abstract

The invention provides a multi-cavity sensing structure for enhancing acoustic signals, which comprises a waveguide and a plurality of resonant cavities, the first end of the waveguide is open, the second end of the waveguide is closed, the resonant cavities are arranged close to the second end of the waveguide, the distances between different resonant cavities and the second end of the waveguide are different, the first end of the waveguide serves as an inlet end of the acoustic signals, and the second end of the waveguide serves as an outlet end of the acoustic signals. The outer ends of the resonant cavities serve as receiving ends of sound signals, each resonant cavity of the multi-cavity sensing structure and the waveguide have different mirror image induction modes, the heights of the resonant cavities can be adjusted to achieve conversion between a mirror image induction continuous domain bound state and a quasi-continuous bound state, sound energy in the resonant cavities of the multi-cavity sensing structure is remarkably enhanced, and the sound signal quality is improved. And moreover, sound signal enhancement in multiple frequency ranges can be realized, detection of weak signals of harmonic noise signals, periodic pulse noise signals and modulation noise signals in strong noise can be realized, and the application range and the actual value of the multi-cavity sensing structure are further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of acoustic signal enhancement, and in particular to a multi-cavity sensing structure for enhancing acoustic signals. Background Art

[0002] Acoustic sensing technology is used in the field of fault diagnosis due to its advantages of rich information, non-contact and flexible installation. However, in the early stage of the fault, the acoustic signal with useful information is very weak and easily interfered by background noise. For example, the weak harmonic signal caused by the early friction and collision of the rotor, the weak periodic pulse signal caused by the local defects of the rolling bearing, and the weak modulation signal generated by the cracked gear are all easily submerged in the background noise. Therefore, it is necessary to improve the signal-to-noise ratio of the weak characteristic signal, that is, to adopt certain processing methods to suppress noise or enhance useful signals. At present, there are two main methods to improve the signal-to-noise ratio of weak signals. One is to process the digital signal obtained by the algorithm, such as time domain method, frequency domain method, time-frequency domain method and detection method based on nonlinear theory; the other is to process the actual acoustic signal based on various acoustic sensing structures, such as phononic crystals, gradient metamaterials, Helmholtz resonant cavity, etc.

[0003] Acoustic metamaterials have attracted extensive attention due to their excellent wave control properties, such as acoustic focusing, acoustic imaging, acoustic tunneling, negative refraction, acoustic rainbow capture, and inverse Doppler effect. In recent years, the research on acoustic enhancement sensing based on acoustic metamaterials has gradually increased. For example, the defect state based on defect phononic crystals can capture and enhance acoustic signals, and improve the signal-to-noise ratio of harmonic signals and periodic pulse signals in strong background noise. Gradient reflection gratings achieve acoustic enhancement effects in a wider operating frequency band and successfully amplify periodic impulse signals and harmonic signals. Through the frequency-selective enhancement characteristics of gradient refractive index acoustic metamaterials, the enhancement of weak bearing fault signals is achieved.

[0004] Continuum bound states have zero radiation decay rate and infinite quality factor, which can greatly enhance the acoustic signal. However, in practical applications, because external excitation can only excite quasi-continuous bound states but not continuous bound states, the continuous bound states must be converted into quasi-continuous bound states with finite high quality factor. In recent years, the continuous bound states of acoustics have attracted more and more attention. In various acoustic systems, a variety of continuous bound states have been studied theoretically and experimentally, including symmetry-protected continuous bound states, Friedrich-Wintgen continuous bound states, Fabry-Perot continuous bound states, and mirror-induced continuous bound states. Through continuous bound states, acoustic signal enhancement and acoustic absorption functions have been achieved. But so far, there are relatively few studies on the enhancement of acoustic signals by quasi-continuous bound states, especially for the enhancement of acoustic signals in different frequency ranges. Summary of the invention

[0005] The purpose of the present invention is to provide a solution based on quasi-continuous domain bound states that can realize multi-frequency range acoustic signal enhancement and be used for weak acoustic signal detection in view of the deficiencies existing in the above-mentioned background technology.

[0006] In order to achieve the above object, the present invention provides a multi-cavity sensing structure for enhancing acoustic signals, comprising a waveguide and a plurality of resonant cavities, wherein the first end of the waveguide is open and the second end is closed, the resonant cavity is arranged close to the second end of the waveguide, and the distance between the resonant cavity and the second end of the waveguide is d i , i is the number of the resonant cavity, and the distance d between the resonant cavities with different numbers and the second end of the waveguide i The first end of the waveguide serves as the entrance end of the acoustic signal, the outer end of the resonant cavity serves as the receiving end of the acoustic signal, each resonant cavity of the multi-cavity sensing structure has a different mirror-induced mode with the waveguide, and the height of the resonant cavity can be adjusted to realize the conversion between the mirror-induced continuous domain bound state and the quasi-continuous bound state.

[0007] Furthermore, the length of the waveguide is set according to actual conditions.

[0008] Furthermore, the inner cross-section of the waveguide is set to be a square with a side length s=120 mm.

[0009] Furthermore, the number of the resonant cavities is set to three, including a first resonant cavity, a second resonant cavity and a third resonant cavity.

[0010] Furthermore, the intracavity thickness of the first resonant cavity is l1=25mm, and the height is h1=140m, the intracavity thickness of the second resonant cavity is l2=25mm, and the height is h2=190m, the intracavity thickness of the third resonant cavity is l3=25mm, and the height is h3=250m, and the distances between the first resonant cavity, the second resonant cavity, and the third resonant cavity and the second end of the waveguide are d1=120mm, d2=155mm, and d3=190mm, respectively, and the width is consistent with the width of the inner cross section of the waveguide.

[0011] Furthermore, the multi-cavity sensing structure is made of acrylic plates, the thickness of the acrylic plates is 10 mm, and different acrylic plates are bonded and connected to each other.

[0012] Furthermore, the multi-cavity sensing structure can enhance acoustic signals in three frequency ranges around 567 Hz, 430 Hz and 332 Hz.

[0013] Furthermore, the acoustic signal enhancement of the multi-cavity sensing structure can detect weak signals in strong noise, including harmonic noise signals, periodic pulse noise signals and modulated noise signals.

[0014] The above scheme of the present invention has the following beneficial effects:

[0015] The multi-cavity sensing structure for enhancing acoustic signals provided by the present invention has multiple resonant cavities at the second end of the waveguide, each resonant cavity and the waveguide have different mirror-induced modes, and the mirror-induced continuous domain bound state and quasi-continuous bound state conversion can be achieved by adjusting the length of the resonant cavity, so that the acoustic energy in the resonant cavity of the multi-cavity sensing structure is significantly enhanced. Therefore, when the acoustic signal enters from the first end of the multi-cavity sensing structure, the enhanced acoustic signal can be received at the top of the resonant cavity of the multi-cavity sensing structure, and the acoustic signal enhancement in multiple frequency ranges can be achieved. At the same time, the detection of weak signals of harmonic noise signals, periodic pulse noise signals and modulated noise signals in strong noise can be achieved, which further improves the application scope and practical value of the multi-cavity sensing structure; in addition, the structure is simple, the production is convenient, and the use cost is low;

[0016] Other beneficial effects of the present invention will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0018] Figure 2 (a) and (b) are schematic diagrams of the air domain of the single cavity structure, (c) is the modal quality factor induced by the first resonant cavity mirror at different heights h1, and (d) is the pressure field distribution of the bound state in the continuous domain induced by the first resonant cavity mirror;

[0019] Figure 3 (a) is a schematic diagram of the simulation calculation of the sound pressure gain spectrum of the single-cavity sensor structure, and (b) is the sound pressure gain spectrum of the first resonant cavity at different heights h1;

[0020] Figure 4 (a) and (b) are schematic diagrams of the air domain of the dual-cavity structure, (c) is the mirror-induced modal quality factor of the second resonant cavity at different heights h2, (d) is the pressure field distribution of the bound state in the continuous domain induced by the mirror-induced second resonant cavity, (e) is the mirror-induced modal quality factor of the first resonant cavity at different heights h2, and (f) is the pressure field distribution of the bound state in the quasi-continuous domain induced by the mirror-induced first resonant cavity;

[0021] Figure 5 (a) is a schematic diagram of the simulation calculation of the sound pressure gain spectrum of the double-cavity structure, (b) is the sound pressure gain spectrum of the second resonant cavity at different heights h2, and (c) is the sound pressure gain spectrum of the first resonant cavity at different heights h2;

[0022] Figure 6(a) and (b) are schematic diagrams of the air domain of the three-cavity structure, (c) is the mirror-induced modal quality factor of the third resonant cavity at different heights h3, (d) is the pressure field distribution of the continuous domain bound state induced by the mirror of the third resonant cavity, (e) and (g) are the mirror-induced modal quality factors of the first resonant cavity and the second resonant cavity at different heights h3, (f) and (h) are the pressure field distribution of the quasi-continuous domain bound state induced by the mirror of the first resonant cavity and the second resonant cavity;

[0023] Figure 7 (a) is a schematic diagram of the simulation calculation of the sound pressure gain spectrum of the three-cavity sensing structure, (b) is the sound pressure gain spectrum of the third resonant cavity at different heights h3, (c) is the sound pressure gain spectrum of the second resonant cavity at different heights h3, (d) is the sound pressure gain spectrum of the first resonant cavity at different heights h3, (e) is the sound pressure gain spectrum of the first, second and third resonant cavities at h1 = 140 mm, h2 = 190 mm, and h3 = 250 mm;

[0024] Figure 8 (a) is the amplitude spectrum measured in free space, (b) is the amplitude spectrum measured in the multi-cavity sensing structure, and (c) is the sound pressure gain spectrum obtained experimentally;

[0025] Fig. 9 This is the harmonic noise signal experiment in the first resonant cavity. (a) and (b) are the time domain diagram and spectrum diagram of the harmonic noise signal measured in free space. (c) and (d) are the time domain diagram and spectrum diagram of the harmonic noise signal measured in the first resonant cavity.

[0026] Fig.10 This is a harmonic noise signal experiment in the second resonant cavity, (a) and (b) are time domain diagrams and spectrum diagrams of the harmonic noise signal measured in free space, (c) and (d) are time domain diagrams and spectrum diagrams of the harmonic noise signal measured in the second resonant cavity;

[0027] Fig.11 The harmonic noise signal experiment in the third resonant cavity, (a) and (b) are the time domain diagram and spectrum diagram of the harmonic noise signal measured in free space, (c) and (d) are the time domain diagram (c) and spectrum diagram (d) of the harmonic noise signal measured in the third resonant cavity;

[0028] Fig.12 The figure is a modulated noise signal experiment in the first resonant cavity. (a), (b), and (c) are the time domain diagram, frequency spectrum diagram, and envelope spectrum diagram of the modulated noise signal measured in free space. (d), (e), and (f) are the time domain diagram, frequency spectrum diagram, and envelope spectrum diagram of the modulated noise signal measured in the first resonant cavity.

[0029] Fig.13This is a modulated noise signal experiment in the second resonant cavity. (a), (b), and (c) are the time domain diagram, frequency spectrum diagram, and envelope spectrum diagram of the modulated noise signal measured in free space. (d), (e), and (f) are the time domain diagram, frequency spectrum diagram, and envelope spectrum diagram of the modulated noise signal measured in the second resonant cavity.

[0030] Fig.14 This is a modulated noise signal experiment in the third resonant cavity. (a), (b), and (c) are the time domain diagram, frequency spectrum diagram, and envelope spectrum diagram of the modulated noise signal measured in free space. (d), (e), and (f) are the time domain diagram, frequency spectrum diagram, and envelope spectrum diagram of the modulated noise signal measured in the third resonant cavity.

[0031] Fig.15 This is the experiment of the periodic pulse noise signal in the first resonant cavity. (a), (b), (c) are the time domain diagram, frequency spectrum diagram and envelope spectrum diagram of the periodic pulse noise signal measured in free space. (d), (e), (f) are the time domain diagram, frequency spectrum diagram and envelope spectrum diagram of the periodic pulse noise signal measured in the first resonant cavity.

[0032] Fig.16 For the periodic pulse noise signal experiment in the second resonant cavity, (a), (b), (c) are the time domain diagram, frequency spectrum diagram and envelope spectrum diagram of the periodic pulse noise signal measured in free space, (d), (e), (f) are the time domain diagram, frequency spectrum diagram and envelope spectrum diagram of the periodic pulse noise signal measured in the second resonant cavity;

[0033] Fig.17 This is the experiment of periodic pulse noise signal in the third resonant cavity. (a), (b), (c) are the time domain diagram, spectrum diagram and envelope spectrum diagram of the periodic pulse noise signal measured in free space. (d), (e), (f) are the time domain diagram, spectrum diagram and envelope spectrum diagram of the periodic pulse noise signal measured in the third resonant cavity. DETAILED DESCRIPTION

[0034] The following describes the embodiments of the present disclosure through specific examples, and those skilled in the art can easily understand other advantages and effects of the present disclosure from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments. The present disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present disclosure. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present disclosure.

[0035] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein may be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present disclosure, it should be understood by those skilled in the art that an aspect described herein may be implemented independently of any other aspect, and two or more of these aspects may be combined in various ways. For example, any number of aspects described herein may be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein may be used to implement this device and / or practice this method.

[0036] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present disclosure, and the illustrations only show the components related to the present disclosure rather than the number, shape and size of the components in actual implementation. The type, quantity and proportion of each component in actual implementation may be changed at will, and the component layout type may also be more complicated. In addition, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the aspects described can be practiced without these specific details.

[0037] like Figure 1 As shown, an embodiment of the present invention provides a multi-cavity sensing structure for enhancing acoustic signals, including a waveguide and a plurality of resonant cavities. As an optional embodiment, the waveguide and the resonant cavity are both formed by bonding acrylic plates after laser cutting, and the plate thickness is preferably 10 mm. The first end of the waveguide (the left end in the figure) is open, and the second end (the right end in the figure) is closed. As a preferred embodiment, in this embodiment, the inner cross-section of the waveguide is set to be a square with a side length s=120 mm, and the change in the length of the waveguide does not affect the performance of the multi-cavity sensing structure, and can be set according to actual conditions.

[0038] The number of resonant cavities can be determined according to demand and actual conditions. They are arranged close to the second end of the waveguide. The distance between the resonant cavity and the second end of the waveguide is d. i , i is the number of the resonant cavity, and the distance d between the resonant cavities with different numbers and the second end of the waveguide iDifferent. Among them, the first end of the waveguide serves as the entrance end of the acoustic signal, and the outer end of the resonant cavity (the top shown in the figure) serves as the receiving end of the (enhanced) acoustic signal. As an optional embodiment, the number of resonant cavities is set to three, and all are set to be rectangular cavities. The cavity thickness of the first resonant cavity is l1=25mm, and the height is h1=140m. The cavity thickness of the second resonant cavity is l2=25mm, and the height is h2=190m. The cavity thickness of the third resonant cavity is l3=25mm, and the height is h3=250m. The distances between the first, second, and third resonant cavities and the second end of the waveguide are d1=120mm, d2=155mm, and d3=190mm, respectively. In addition, the widths of the first, second, and third resonant cavities are consistent with the width of the cross-section inside the waveguide, that is, the side length s.

[0039] Each resonant cavity and waveguide of the multi-cavity sensing structure has a mirror-induced mode, and the mirror-induced continuous domain bound state and quasi-continuous domain bound state conversion can be achieved by adjusting the height of the resonant cavity. The pressure field distribution of the mirror-induced continuous domain bound state and quasi-continuous domain bound state shows that the acoustic energy is significantly enhanced in the resonant cavity of the multi-cavity sensing structure, so the acoustic signal enters from the left end of the multi-cavity sensing structure and receives the enhanced acoustic signal at the top of the resonant cavity of the multi-cavity sensing structure.

[0040] It should be noted that each resonant cavity and waveguide may be arranged vertically or at a certain inclination. In this embodiment, the vertical arrangement is taken as an example for description.

[0041] The multi-cavity sensing structure using three resonant cavities provided in this embodiment can enhance the acoustic signal in three frequency ranges near 567 Hz, 430 Hz and 332 Hz. At the same time, the detection of weak signals of harmonic noise signals, periodic pulse noise signals and modulated noise signals in three frequency ranges near 567 Hz, 430 Hz and 332 Hz in strong noise can be achieved. The following is a specific case to further verify and illustrate the role and effect of the multi-cavity sensing structure provided in this embodiment.

[0042] In the simulation software COMSOL, the air domain and the single cavity structure with only the first resonant cavity are first modeled. The geometric parameters are s = 120 mm, l1 = 25 mm, h1 is a variable, d1 = 120 mm, and the total length of the waveguide is 500 mm. The first end of the waveguide is set as a perfectly matched layer boundary, and the other boundaries are rigid boundaries. Of course, in order to simulate the actual thermoviscous loss, the rigid boundary of the model can also be changed to the thermoviscous boundary layer impedance. The eigenmodes and eigenfrequencies of the single cavity structure composed of the waveguide and the first resonant cavity are calculated by the eigenmode analysis of the pressure acoustics module. Since the single cavity structure is an open system, its eigenfrequency is a complex number ω = ω0-iγ. The quality factor of the mode can be calculated by Q = ω0 / 2γ. Find the mirror-induced eigenmodes under different h1, calculate the corresponding quality factors and connect them into lines.

[0043] like Figure 2 , Figure 3 As shown in the figure, at h1 = 117mm, the image-induced modal quality factor reaches a maximum value and becomes a continuous domain bound state. Under other h1 conditions, the image-induced mode is a quasi-continuous domain bound state. The frequency response analysis of the single-cavity structure shows that the pressure field distribution of the image-induced mode indicates that the acoustic energy is concentrated at the first resonant cavity, so the sound wave is incident from the first end of the waveguide and received at the top of the first resonant cavity. The incident sound pressure is p0, the received sound pressure is p, and the sound pressure gain is p / p0. Because the continuous domain bound state cannot be excited by external sound waves, the parameter of h1 should avoid 117mm and select other values. The sound pressure gain spectrum of the first resonant cavity with h1 = 120mm, 130mm, 140mm, 150mm and 160mm is calculated. When h1 = 140mm, the first resonant cavity achieves the maximum gain at 567Hz, and can have a large sound pressure gain in the range near 567Hz. Therefore, h1 = 140mm is selected.

[0044] At the same time Figure 4 , Figure 5As shown in the figure, a second resonant cavity is added to the model to form a dual-cavity structure. The original parameters of the first resonant cavity remain unchanged, and the parameters of the second resonant cavity are l2=25mm, h2 is a variable, and d2=155mm. The second resonant cavity and the waveguide also have mirror-induced modes. The quality factor of the mirror-induced eigenmode of the second resonant cavity under different h2 is calculated. It is found that at h2=155mm, the quality factor of the mirror-induced mode of the second resonant cavity reaches a maximum value and becomes a continuous domain bound state. At the same time, the quality factor of the mirror-induced eigenmode of the first resonant cavity under different h2 is also calculated. It can be seen that the change of the height h2 of the second resonant cavity will not affect the mirror-induced eigenmode of the first resonant cavity. Further calculation of the sound pressure gain spectrum of the first resonant cavity and the second resonant cavity under different h2 shows that the change of the height h2 of the second resonant cavity will hardly affect the sound pressure gain of the first resonant cavity near 567Hz. At h2=190mm, the second resonant cavity achieves the maximum gain at 430Hz and can have a large sound pressure gain in the range near 430Hz. Therefore, h2=190mm is selected.

[0045] At the same time Figure 6 , Figure 7 As shown in the figure, a third resonant cavity is added to the model to form a three-cavity structure. The parameters of the original first and second resonant cavities remain unchanged. The parameters of the third resonant cavity are l3 = 25mm, h3 is a variable, and d3 = 190mm. Through the analysis of the eigenmode and frequency response, it can be found that at h3 = 250mm, the third resonant cavity achieves the maximum gain at 332Hz and can have a large sound pressure gain in the range near 332Hz. Therefore, h3 = 250mm is selected.

[0046] Therefore, the multi-cavity sensing structure provided in this embodiment can achieve sound pressure enhancement in three frequency ranges near 567 Hz, 430 Hz and 332 Hz. Of course, the number of resonant cavities is not limited to three, and can be added if necessary to achieve sound pressure enhancement in more frequency ranges.

[0047] At the same time, the effect of the multi-cavity sensing structure is further verified through experiments in this embodiment. A 10 mm thick acrylic plate is cut by laser and bonded into a multi-cavity sensing structure with three resonant cavities, and the speaker emits a sound signal. When there is no multi-cavity sensing structure, the microphone measures the contrast sound signal of the free space at a horizontal distance of 200 mm from the speaker. When there is a multi-cavity sensing structure, the microphone is located at the top of the corresponding resonant cavity, and the enhanced sound signal is also measured at a horizontal distance of 200 mm from the speaker. The speaker is set to emit harmonic sound signals from 200 Hz to 800 Hz with a step size of 1 Hz in sequence, and the amplitudes are measured in the free space and the multi-cavity sensing structure respectively, and the sound pressure gain of the multi-cavity sensing structure is obtained by comparing the amplitude of the multi-cavity sensing structure with the amplitude of the free space. Figure 8As shown in the figure, the experimental results verify that the multi-cavity sensing structure can achieve a large sound pressure gain in all three resonant cavities. The sound pressure gain frequency ranges corresponding to the first, second and third resonant cavities are three frequency ranges near 560Hz, 433Hz and 320Hz. It should be noted that the frequency range deviation between the experimental results and the simulation results is caused by the processing error of the multi-cavity sensing structure.

[0048] In addition, the present embodiment also verifies the harmonic noise signal, the periodic pulse noise signal and the modulated noise signal. First, the speaker is set to emit three harmonic noise signals with a signal-to-noise ratio of -35dB and f=560Hz, 433Hz, and 320Hz:

[0049] S(t)=[1+0.5×cos(2π×f0×t)]×cos[2π×f×t+0.5×cos(2π×f0×t)]+noise(t) and the signals are measured in the free space and the three resonant cavities of the multi-cavity sensing structure. Figure 9-11 As shown, the experimental results indicate that the three resonant cavities of the multi-cavity sensing structure respectively enhance the harmonic components in the three harmonic noise signals, making the harmonic signals more obvious.

[0050] Then set the speaker to emit three types of modulated noise signals with f0=5Hz:

[0051] S(t)=[1+0.5×cos(2π×f0×t)]×cos[2π×f×t+0.5×cos(2π×f0×t)]+noise(t)

[0052] The parameters are respectively SNR -20dB and f = 560Hz, SNR -20dB and f = 433Hz, SNR -15dB and f = 320Hz, and the signals are measured in the three resonant cavities of free space and multi-cavity sensing structure. Figure 12-14 As shown, the experimental results indicate that the three resonant cavities of the multi-cavity sensing structure respectively enhance the modulated signal components in the three modulated noise signals, making the signal features more prominent and easier to identify.

[0053] Finally, the speaker is set to emit three types of periodic pulse noise signals with a pulse interval of 0.2s:

[0054] S(t)=e-50t×cos(2π×f×t)+noise(t)

[0055] The parameters are -25dB signal-to-noise ratio and f=560Hz, -20dB signal-to-noise ratio and f=433Hz, and -15dB signal-to-noise ratio and f=320Hz, respectively, and the signals are measured in the three resonant cavities of the free space and multi-cavity sensing structure. Figure 15-17As shown, the experimental results indicate that the three resonant cavities of the multi-cavity sensing structure respectively enhance the periodic pulse signal components in the three periodic pulse noise signals, making the characteristic signals more obvious.

[0056] From the above, it can be seen that the multi-cavity acoustic sensing structure successfully enhances the harmonic signals, periodic pulse signals and modulated signals in multiple frequency ranges under strong noise based on the quasi-continuous domain bound states of multiple resonant cavities, making the signal characteristics more obvious and easy to identify, and can be used for weak acoustic signal detection in multiple frequency ranges.

[0057] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0058] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the application. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A multi-cavity sensing structure for enhancing acoustic signals, characterized in that: The invention comprises a waveguide and a plurality of resonant cavities, wherein the first end of the waveguide is open and the second end is closed, the resonant cavity is arranged close to the second end of the waveguide, and the distance between the resonant cavity and the second end of the waveguide is d i , i is the number of the resonant cavity, and the distance d between the resonant cavities with different numbers and the second end of the waveguide i The first end of the waveguide serves as the entrance end of the acoustic signal, the outer end of the resonant cavity serves as the receiving end of the acoustic signal, each resonant cavity of the multi-cavity sensing structure has a different mirror-induced mode with the waveguide, and the height of the resonant cavity can be adjusted to realize the conversion between the mirror-induced continuous domain bound state and the quasi-continuous bound state.

2. The multi-cavity sensing structure for enhancing acoustic signals according to claim 1, characterized in that: The length of the waveguide is set according to actual conditions.

3. The multi-cavity sensing structure for enhancing acoustic signals according to claim 1, characterized in that: The inner cross-section of the waveguide is arranged to be a square with a side length s=120 mm.

4. The multi-cavity sensing structure for enhancing acoustic signals according to claim 1, characterized in that: The number of the resonant cavities is set to three, including a first resonant cavity, a second resonant cavity and a third resonant cavity.

5. The multi-cavity sensing structure for enhancing acoustic signals according to claim 4, characterized in that: The first resonant cavity has an intracavity thickness of l1=25mm and a height of h1=140m, the second resonant cavity has an intracavity thickness of l2=25mm and a height of h2=190m, the third resonant cavity has an intracavity thickness of l3=25mm and a height of h3=250m, and the distances between the first resonant cavity, the second resonant cavity, and the third resonant cavity and the second end of the waveguide are d1=120mm, d2=155mm, and d3=190mm, respectively, and their widths are consistent with the width of the inner cross section of the waveguide.

6. The multi-cavity sensing structure for enhancing acoustic signals according to claim 1, characterized in that: The multi-cavity sensing structure is made of acrylic plates, the thickness of the acrylic plates is 10 mm, and different acrylic plates are bonded and connected to each other.

7. The multi-cavity sensing structure for enhancing acoustic signals according to claim 5, characterized in that: The multi-cavity sensing structure can enhance acoustic signals in three frequency ranges around 567 Hz, 430 Hz and 332 Hz.

8. The multi-cavity sensing structure for enhancing acoustic signals according to claim 1, characterized in that: The acoustic signal enhancement of the multi-cavity sensing structure can detect weak noise signals in strong noise, including harmonic noise signals, periodic pulse noise signals and modulated noise signals.

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