Real-time voiceprint protection device based on acoustic metamaterial and preparation method thereof

Abstract

The application discloses a real-time voiceprint protection device based on Mie resonance acoustic metamaterial and a preparation method thereof, and belongs to the field of voice physical privacy protection. The device adopts a central cavity and three Mie resonance metamaterial units which are arranged around the periphery of the central cavity, and combines a narrow-band Mie resonance structure formed by an adjustable coupling resonance structure arranged in the Mie resonance metamaterial unit, so that only low-frequency sound waves which are targetedly disturbed at 300-700 Hz and bear physiological characteristics of human voice are reserved, the semantic signals of medium and high frequencies are completely reserved, voiceprint anonymous protection and human voice intelligibility are considered, a three-unit symmetrical layout can cover a daily sound emission angle of plus or minus 90 degrees, voiceprint leakage dead angles caused by user head turning and displacement are eliminated, power supply is not needed, a microphone does not need to be modified, and software operation is not needed; with the aid of three core designs of narrow-band frequency selection disturbance, multi-unit surrounding full coverage and passive mechanical random frequency modulation, voiceprint anonymity in all scenes is realized on the premise of reserving voice intelligibility, the preparation process is simple, and the device has strong universality.

Description

Technical Field

[0001] This invention belongs to the fields of acoustic metamaterials and voice physical privacy security technology, and relates to voiceprint protection devices and their preparation methods, specifically to a real-time voiceprint protection device based on acoustic metamaterials and its preparation method. Background Technology

[0002] Voiceprints, determined by the unique physiological structure of the human vocal cords and vocal tract, possess a high degree of uniqueness and are widely used as a stable biometric identifier in scenarios such as financial verification, access control login, judicial evidence collection, and real-name registration for meetings. Various mobile phones, meeting gooseneck microphones, and handheld recording devices pose significant audio acquisition security risks. Recording software and underlying firmware are easily hijacked by malicious programs, and external miniature eavesdropping devices can also intercept raw human voice waveforms. Once the pure, original audio is illegally obtained, it can be used to train voice cloning models and reverse engineer a user's original voiceprint using spectral algorithms, enabling identity theft, telecommunications fraud, forgery of evidence, and other acts that result in serious privacy breaches and financial losses.

[0003] Existing voiceprint protection solutions fall into two categories: software post-processing and active hardware modification with built-in microphones. Software perturbation schemes add perturbations or transformations to the voice signal after the microphone has completed audio acquisition and signal digitization to hide voiceprint characteristics. These schemes assume the microphone, firmware, and recording software are trusted devices; once the acquisition device is compromised, attackers can intercept the original audio before software processing, rendering the protection mechanism completely ineffective. Furthermore, software computation incurs additional latency and device resource overhead. Real-time computation generates latency and consumes processor power, making it difficult to deploy on mobile devices and low-cost audio pickup devices.

[0004] The built-in hardware modification solution integrates the voiceprint interference module into the microphone cavity, which improves security. However, this type of solution relies on a specific voice encoding format, has poor universality, and is only compatible with dedicated microphone devices. It cannot be deployed in public places or third-party shared microphone scenarios.

[0005] Traditional acoustic metamaterials-related devices can control the amplitude and phase of sound waves through microcavities, but existing products are only used for noise reduction and ultrasonic interception, and there is no acoustic isolation design for the pickup front end. Traditional single-cavity structures are also only effective for sound waves at fixed angles, indicating a significant technological gap.

[0006] Existing technologies suffer from several drawbacks: First, they suffer from frequency band conflicts. Identification features are concentrated in the low-frequency range of 300-700Hz, while dialogue semantics are stored in the mid-to-high frequencies. Interference across the entire spectrum will simultaneously destroy the voice content, making it impossible to balance protection and normal communication. Second, they have poor angular robustness. The single-cavity structure is only effective when directly facing the microphone. When the user turns their head or moves, a blind spot is created, making it easy for voiceprints to be leaked. Third, the interference spectrum is fixed. After attackers collect a sufficient amount of noisy frequencies, they can use machine learning and filtering algorithms to remove the interference and restore the original voiceprint, resulting in insufficient long-term protection reliability. Fourth, they have weak versatility. Software, built-in hardware, and traditional metamaterials cannot be directly connected to various microphones, making deployment in public and temporary interview scenarios difficult. Summary of the Invention

[0007] The purpose of this invention is to provide a passive external real-time voiceprint protection device based on acoustic metamaterials and its preparation method. It requires no power supply, no microphone modification, and does not rely on software calculation. With the help of three core designs, including narrowband frequency selection perturbation, multi-unit surround full coverage, and passive mechanical random frequency tuning, it achieves voiceprint anonymity in all scenarios while preserving speech intelligibility, filling the technical gap of passive physical layer voiceprint protection at the microphone acquisition end.

[0008] This invention is achieved through the following technical solution: A real-time acoustic signature protection device based on acoustic metamaterials includes a central cavity formed by a cylindrical structure that is closed at the top and open at the bottom. Three sets of Mie resonant metamaterial units are evenly distributed along the circumferential direction of the outer periphery of the central cavity. The three sets of Mie resonant metamaterial units are arranged in a staggered manner along the axial direction. The Mie resonance metamaterial unit includes a fan-shaped shell integrally formed with the central cavity. The fan-shaped shell includes a bottom wall and a side wall, and a top cover that is symmetrically disposed with respect to the bottom wall and snapped onto the top of the side wall. The Mie resonance metamaterial unit forms a resonant cavity along the radial central axis through parallel thin walls. A through hole is provided on the side wall of the central cavity corresponding to the first end of the resonant cavity. A vertical groove is provided at the tail end of the resonant cavity through the side wall of the fan-shaped shell. The resonant cavity has side cavities on both sides, and the side cavities are connected to the resonant cavity through a thin-walled narrow slit near the central cavity; A coupled resonant structure is radially arranged near the thin wall inside the side cavity; The bottom end of the central cavity is coaxially connected to a cylindrical microphone limiting slot with open upper and lower ends.

[0009] The present invention also has the following technical features: Preferably, the coupled resonance structure includes a slide rail and a reciprocating sliding tuning block corresponding to the slide rail.

[0010] Furthermore, there are two slide rails spaced apart from each other, and a limiting block is provided at the middle of one end face of each slide rail.

[0011] Furthermore, the limiting blocks located in the side cavities on both sides of the resonant cavity within the Mie resonance metamaterial unit are respectively set at both ends of the slide rail.

[0012] Preferably, the outer edge of the top cover is provided with a slot corresponding to the resonant cavity.

[0013] Furthermore, the geometric parameters of the Mie resonance metamaterial unit are as follows: central cavity diameter 12~28mm; outer arc length of the fan-shaped outer shell 48~51mm; radial length of the resonant cavity 14~25mm; The slide rail is 8mm thick; the reciprocating sliding tuning block is 4~16mm long, 5mm wide and 5mm high, and has an adjustment range of 4~16mm.

[0014] Furthermore, the geometric parameters of the Mie resonance metamaterial unit are as follows: central cavity diameter 19.5 mm, fan-shaped outer arc length 49.5 mm, resonant cavity radial length 21 mm, thin wall thickness 1.95 mm, slide rail 8 mm, reciprocating sliding tuning block length 8 mm, width and height both 5 mm.

[0015] This invention also protects the preparation method of the above-mentioned real-time acoustic fingerprint protection device based on acoustic metamaterials, which is integrally formed by photosensitive resin 3D printing.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention employs a central cavity and three Mie resonant metamaterial units surrounding the central cavity, combined with an adjustable coupling resonant structure built into the Mie resonant metamaterial units to form a narrowband Mie resonant structure. This structure specifically disturbs low-frequency sound waves (300-700Hz) that carry the physiological characteristics of human voices, while fully preserving mid-to-high-frequency semantic signals, thus balancing voiceprint anonymity protection with voice intelligibility. The symmetrical layout of the three units can cover ±90° of daily speaking angles, eliminating dead zones for voiceprint leakage caused by user head turning or displacement. The passive sliding block inside the Mie resonant metamaterial unit automatically adjusts the effective size of the cavity based on human body vibration, continuously generating time-varying random interference spectra, significantly improving the security strength against filtering modeling and voice cloning attacks. The entire device is a passive external accessory, requiring no power supply or modification of microphone hardware, and is compatible with various pickup devices such as mobile phones, handheld microphones, and gooseneck microphones. It blocks the risk of original voiceprint theft caused by microphone hijacking and covert eavesdropping from the physical source, eliminating audio latency issues caused by software computation. The interference gain is stably maintained in complex scenarios such as noisy and windy conditions, resulting in stronger protection robustness. This invention utilizes a photopolymerization process to fabricate the acoustic metamaterial unit, integrating the complex cavity, sound guiding channel, and guiding and limiting structure of the acoustic metamaterial into a single unit. This reduces assembly gaps between components, prevents sound wave leakage, and ensures the preset Mie resonance response performance of the acoustic metamaterial. This fabrication method can accurately reproduce the fine geometric dimensions of the metamaterial cavity, such as wall thickness, cavity diameter, and coupling slits, ensuring the consistency of the acoustic metamaterial's resonance characteristics in mass production and significantly reducing the workload of acoustic calibration of finished products. Different microphone carriers can be adapted simply by changing the dimensions of the peripheral assembly structure; the core resonant configuration of the acoustic metamaterial does not require redesign and processing, exhibiting excellent versatility. The fabrication process eliminates the need for circuit component assembly, simplifying the process and controlling production costs. The resulting acoustic metamaterial structure is lightweight and robust, facilitating the fabrication of modular units for rapid assembly, disassembly, and portability, making it suitable for deployment in various scenarios. Attached Figure Description

[0017] Figure 1 This is a top view structural diagram of the present invention with the top end cap of the central cavity and the top cover of the Mie resonance metamaterial unit removed. Figure 2 This is a structural schematic diagram of the invention from a top view. Figure 3 This is a schematic diagram of the axial cross-section of the present invention; Figure 4 The effect of the change in the total length of the coupled resonant structure on the frequency; The labels in the diagram represent the following: 1-Central cavity, 101-Through hole, 2-Mi resonant metamaterial unit, 201-Fan-shaped shell; 20101-Bottom wall, 20102-Side wall, 20103-Top cover, 2010301-Slot, 202-Thin wall, 203-Resonance cavity, 20301-Vertical slot; 204-Side cavity, 205-Thin wall narrow slit; 3-Coupled resonant structure, 301-Slide rail, 302-Reciprocating sliding tuning block, 303-Limiting block; 4-Microphone limiting slot. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0019] refer to Figures 1-3 As shown, this embodiment provides a real-time acoustic signature protection device based on acoustic metamaterials, including a central cavity 1 formed by a cylindrical structure with a closed top and an open bottom. Three sets of Mie resonant metamaterial units 2 are evenly distributed around the outer periphery of the central cavity 1, and the three sets of Mie resonant metamaterial units 2 are staggered along the axial direction. Targeted perturbation is effective when the speaker is stationary and facing the microphone. In practice, speech is often dynamic: speakers naturally turn their heads and adjust their posture, changing the angle of incidence and the propagation path of the sound to the microphone. For direction-sensitive acoustic structures, even small angular deviations can significantly reduce the intensity of the perturbation, leading to inconsistent anonymization results. This angle sensitivity poses a risk of voiceprint leakage because identity-carrying features may escape perturbation in certain directions. Therefore, robust voiceprint protection requires maintaining strong perturbation over a wide range of speaking angles, not just in a fixed, ideal direction.

[0020] This problem is addressed by designing a dynamically stable metamaterial arrangement that maintains strong perturbations at common speaking angles. By simulating realistic speaker motion and microphone geometry, we determined a three-unit Mie resonant metamaterial arrangement whose combined response provides consistent anonymization under natural user motion without active perception or control.

[0021] The Mie resonance metamaterial unit 2 includes a fan-shaped shell 201 integrally formed with the central cavity 1. The fan-shaped shell 201 includes a bottom wall 20101 and a side wall 20102, and a top cover 20103 symmetrically disposed with the bottom wall 20101 and snapped onto the top of the side wall 20102. The side wall 20102 is provided with multiple snap holes at radial intervals, and the top cover 20103 is provided with multiple snap rods corresponding to the snap holes. The snap holes and snap rods are engaged and disengaged to realize the snapping and disassembly of the top cover 20103, and further realize the adjustment of the coupled resonance structure.

[0022] The Mie resonance metamaterial unit 2 forms a resonant cavity 203 along its radial central axis through parallel thin walls 202. A through-hole 101 is provided on the side wall of the central cavity 1 corresponding to the head end of the resonant cavity 203. A vertical groove 20301 is provided at the tail end of the resonant cavity 203, penetrating the side wall 20102 of the fan-shaped outer shell 201. The geometric parameters of the Mie resonance metamaterial unit 2 are: diameter of the central cavity 1 12~28 mm; outer arc length of the fan-shaped outer shell 201 48~51 mm; radial length of the resonant cavity 203 14~25 mm. The slide rail 301 is 8 mm long; the reciprocating sliding tuner block 302 is 4–16 mm long, 5 mm wide and 5 mm high, and the coupling resonant structure 3 has an adjustment range of 4–16 mm. Under these constraints, the interference center frequency remains within the target 50 Hz frequency band, and the interference amplitude changes only slightly. Changing the metamaterial thickness has little effect on the resonant frequency and interference intensity. This is because the thickness primarily provides mechanical support and does not significantly alter the effective cavity size or acoustic boundary conditions of the dominant resonant mode. Therefore, this design maintains stable acoustic performance while allowing flexibility in thickness to accommodate microphones of different sizes, improving practical deployment capabilities. Figure 4 The effect of changes in the total length of the coupled resonant structure on the frequency; such as Figure 4 As shown, the change in the total length of the coupled resonant structure causes the interference center frequency to shift, while the interference gain remains above 72 times.

[0023] The resonant cavity 203 has side cavities 204 on both sides, and the side cavities 204 are connected to the resonant cavity 203 through a thin-walled narrow slit 205 near the central cavity 1. A coupling resonance structure 3 is radially arranged inside the side cavity 204 near the thin wall 202; the coupling resonance structure 3 includes a slide rail 301 and a reciprocating sliding tuning block 302 corresponding to the slide rail 301. The coupling resonance structure 3 is located near the middle of the thin wall 202.

[0024] There are two slide rails 301 with relative intervals, and a limit block 303 is provided in the middle of one end face of the two slide rails 301.

[0025] Within a Mie resonant metamaterial unit 2, limiting blocks 303 located in the side cavities 204 on either side of the resonant cavity 203 are respectively disposed at both ends of the slide rail 301. For devices of different sizes, only minor adjustments to the dimensions of the coupled resonant structure 3 are required, and passive randomization effectively enhances safety without reducing acoustic perturbation performance. Since these changes do not alter the core metamaterial structure, interference performance remains unaffected.

[0026] The bottom of the central cavity 1 is coaxially connected to a cylindrical microphone limiting slot 4 with open top and bottom ends.

[0027] The outer edge of the top cover 20103 is provided with a slot 2010301 corresponding to the resonant cavity 203.

[0028] A narrow-band Mie resonance structure is constructed by using a central cavity 1 and three Mie resonance metamaterial units 2 surrounding the central cavity 1, combined with an adjustable coupling resonance structure 3 built into the Mie resonance metamaterial units 2, to specifically perturb the 300-700Hz frequency range. The device carries low-frequency sound waves that retain the physiological characteristics of human voices, while preserving mid-to-high frequency semantic signals. It balances voiceprint anonymity protection with voice intelligibility. The symmetrical layout of the three units can cover ±90° of daily speaking angles, eliminating blind spots for voiceprint leakage caused by user head turning or displacement. The passive sliding block inside the Mie resonant metamaterial unit 2 automatically adjusts the effective size of the cavity based on human body vibration, continuously generating time-varying random interference spectrum, which greatly improves the security strength against filtering modeling and voice cloning attacks. The entire device is a passive external accessory, requiring no power supply or modification of microphone hardware. It can be adapted to various pickup devices such as mobile phones, handheld microphones, and gooseneck microphones, blocking the risk of original voiceprint theft caused by microphone hijacking and covert eavesdropping from the physical source. There is no audio latency problem caused by software calculation. The interference gain is stably maintained in complex scenarios such as noisy and windy conditions, making the protection more robust. The real-time voiceprint protection device based on acoustic metamaterials of this invention achieves full-scene voiceprint anonymity by simply placing the microphone within the microphone limiting slot 4, while preserving speech intelligibility. It requires no power supply, no microphone modification, and no software computation. Through three core design features—narrowband frequency selection perturbation, multi-unit surround full coverage, and passive mechanical random frequency tuning—it fills the technological gap in passive physical layer voiceprint protection at the microphone acquisition end. For devices of different sizes, only minor adjustments to the dimensions of the coupling resonance structure 3 are needed to ensure the preset Mie resonance response performance of the acoustic metamaterial. Adaptation to different microphone carriers can be achieved simply by changing the dimensions of the peripheral assembly structure. The core resonant configuration of the acoustic metamaterial does not require redesign or reprocessing, demonstrating strong versatility.

[0029] The real-time acoustic signature protection device based on acoustic metamaterials of this invention is integrally molded using photosensitive resin SLA 3D printing. The complex cavity, sound guiding channel, and guiding and limiting structure of the acoustic metamaterial are integrally molded, reducing assembly gaps between components, preventing sound wave leakage, and ensuring the preset Mie resonance response performance of the acoustic metamaterial. This fabrication method can accurately reproduce the fine geometric dimensions of the metamaterial cavity, such as wall thickness, cavity diameter, and coupling slits, ensuring the consistency of the acoustic metamaterial's resonance characteristics in mass production and significantly reducing the workload of acoustic calibration of finished products. Different microphone carriers can be adapted simply by changing the dimensions of the peripheral assembly structure; the core resonant configuration of the acoustic metamaterial does not need to be redesigned and processed, exhibiting good versatility. The fabrication process does not require the assembly of circuit components, making the process simple and production costs controllable. The molded acoustic metamaterial structure is lightweight and robust, easy to process into modular units, and allows for rapid assembly, disassembly, and portability, making it suitable for deployment in multiple scenarios.

[0030] The geometric dimensions of each structure in this device directly determine the Mie resonance frequency, acoustic interference gain, sound emission angle coverage stability, and resistance to reverse attacks. The resonance satisfies… Acoustic principles: The larger the effective acoustic path length L of the cavity, the lower the resonant center frequency of the device; deviations of the dimensions of each component from the design range will cause the disturbance frequency band to deviate from the characteristic range of the first resonance peak of human voice in the range of 300~700Hz, significantly reducing the anonymity protection effect of the acoustic signature. The overall axial thickness of the cavity only serves a mechanical support function and has no significant impact on the resonance performance. This invention limits the feasible range of dimensions for each key structure: the diameter of the central cavity 1 is 12~28mm; the outer arc length of the fan-shaped outer shell 201 is 48~51mm; the radial length of the resonant cavity 203 is 14~25mm; in the coupled resonance structure 3, the length of the slide rail 301 is fixed at 8mm, the height of the slide rail 301 is 5mm, the length of the reciprocating sliding tuning block 302 is adjustable in the range of 4~16mm, the width and height of the reciprocating sliding tuning block 302 are uniformly 5mm, and the thickness of the thin wall 202 separating the resonant cavity 203 is 1.95mm.

[0031] The present invention preferably uses the following optimal reference geometric parameters: the diameter of the central cavity 1 is 19.5 mm, the height of the central cavity 1 is 23 mm, the outer arc length of the fan-shaped outer shell 201 is 49.5 mm, the width of the resonant cavity 203 is 6.81 mm, the height is 10.1 mm, the thickness of the thin wall 202 is 1.95 mm, the length of the slide rail 301 is 8 mm, and the length of the reciprocating sliding tuning block 302 under static reference is 8 mm. Except for the thin wall 202, all other thicknesses are 36 mm. The width of the through hole 101 and the thin-walled narrow slit 205 is 2 mm, and their height corresponds to the depth of the resonant cavity 203. Using the highest layer Mie resonance metamaterial unit 2 as a reference, the second and third layers of Mie resonance metamaterial units 2 are staggered by 2.81 mm and 3.3 mm, respectively. The optimal size design principle is as follows: the 19.5mm central cavity 1, with a diameter in the middle of the 12~28mm range, ensures uniform acoustic field coupling for the three fan-shaped metamaterial units, with the resonant center precisely falling within the 500Hz human voice characteristic frequency band; the 49.5mm outer arc length of the fan-shaped outer shell 201 matches the effective acoustic path length required for 500Hz, and simulation tests show that the peak gain of acoustic interference can reach 73 times. The ±0.1mm machining tolerance of SLA photosensitive resin 3D printing only results in ±5Hz. The resonance offset and gain fluctuation are less than 0.3 times, and the acoustic performance is stable in batch production. The radial length of the 21mm resonant cavity 203 is the optimal channel size, which can achieve high-intensity low-frequency amplification. If the radial length is less than 14mm, the interference gain will drop below 40 times, and the voiceprint matching failure rate cannot reach the protection standard of more than 90%. The 1.95mm separating thin wall 202 can balance the acoustic coupling strength between the main resonant cavity and the side cavity, which not only ensures the directional amplification of low-frequency voiceprint signals but also avoids the spread of sound wave crosstalk to the mid-to-high frequency semantic band, ensuring speech intelligibility. The coupled resonant structure 3 is matched with a size matching cavity. The internal space features a 5mm wide and high reciprocating tuning block 302 that slides smoothly without jamming. An 8mm slide rail 301 provides stable guidance. The reciprocating tuning block 302 has a full stroke of 4~16mm, which allows the resonant frequency to dynamically drift in the range of 518Hz~540Hz. The total frequency fluctuation range is 22.8Hz, and the interference gain is maintained stably at more than 72 times throughout the entire range. When the 8mm tuning block is selected statically, even slight shaking of the human body can cover the entire frequency range and continuously generate time-varying random interference spectrum, effectively resisting various adaptive attacks such as inverse filtering, fine-tuning voiceprint recognition, and voice cloning.

[0032] The optimal-sized prototype was fabricated using SLA photosensitive resin 3D printing, and a soundproof chamber acoustic testing platform was built for physical testing. The prototype was placed over a mobile phone microphone and a gooseneck conference microphone, with the sound source 30cm away from the pickup device. Human voice samples were collected from testers of different ages and genders. The results showed that within a ±90° range of normal vocal radiance, the voiceprint matching failure rate (MMR) remained consistently above 95%, and the voiceprint recognition error rate (EER) was above 40%. The automatic speech word recognition accuracy was above 96%, and the subjective speech MOS score reached 4.6, demonstrating the ability to fully preserve human speech semantic information while destroying the 300-700Hz identity voiceprint characteristics. Adversarial tests were conducted against adaptive attack scenarios such as voice cloning and reverse spectrum reconstruction; even with this device installed, the voiceprint matching failure rate remained at 92%. For manufacturing consistency testing, multiple batches of printed prototypes showed a maximum resonant frequency shift of only ±6Hz and gain fluctuation of no more than 0.4 times within a ±0.1mm manufacturing tolerance. The prototype can fit snugly against various cylindrical and square miniature microphones, requires no additional power supply, and has a stable and reliable passive structure that can provide stable protection in noisy indoor and outdoor light wind environments.

Claims

1. A real-time acoustic signature protection device based on acoustic metamaterials, characterized in that, The central cavity (1) is formed by a cylindrical structure that is closed at the top and open at the bottom. Three sets of Mie resonance metamaterial units (2) are evenly distributed around the outer periphery of the central cavity (1). The three sets of Mie resonance metamaterial units (2) are arranged in staggered layers along the axial direction. The Mie resonance metamaterial unit (2) includes a fan-shaped shell (201) integrally formed with the central cavity (1). The fan-shaped shell (201) includes a bottom wall (20101) and a side wall (20102), and a top cover (20103) symmetrically arranged with the bottom wall (20101) and fastened to the top of the side wall (20102). The Mie resonance metamaterial unit (2) forms a resonant cavity (203) along the radial central axis through parallel thin walls (202). A through hole (101) is provided on the side wall of the central cavity (1) corresponding to the first end of the resonant cavity (203). A vertical groove (20301) is provided at the tail end of the resonant cavity (203) through the side wall (20102) of the fan-shaped shell (201). The resonant cavity (203) is provided with side cavities (204) on both sides, and the side cavities (204) are connected to the resonant cavity (203) through a thin-walled narrow slit (205) near the central cavity (1); A coupled resonance structure (3) is provided radially near the thin wall (202) inside the side cavity (204); The bottom end of the central cavity (1) is coaxially connected to a cylindrical microphone limiting slot (4) with open upper and lower ends.

2. The real-time acoustic signature protection device based on acoustic metamaterials according to claim 1, characterized in that, The coupled resonance structure (3) includes a slide rail (301) and a reciprocating sliding tuning block (302) corresponding to the slide rail (301).

3. The real-time acoustic signature protection device based on acoustic metamaterials according to claim 2, characterized in that, The slide rails (301) are arranged at relative intervals, and a limiting block (303) is provided at the middle of one end face of each of the two slide rails (301).

4. The real-time acoustic signature protection device based on acoustic metamaterials according to claim 3, characterized in that, The limiting blocks (303) located in the side cavities (204) on both sides of the resonant cavity (203) of the Mie resonance metamaterial unit (2) are respectively set at both ends of the slide rail (301).

5. The real-time acoustic signature protection device based on acoustic metamaterials according to claim 1, characterized in that, The outer edge of the top cover (20103) and the resonant cavity (203) are respectively provided with slots (2010301).

6. The real-time acoustic signature protection device based on acoustic metamaterials according to claim 3, characterized in that, The geometric parameters of the Mie resonance metamaterial unit (2) are as follows: central cavity (1) diameter 12~28mm; fan-shaped shell (201) outer arc length 48~51mm; resonance cavity (203) radial length 14~25mm; The slide rail (301) is 8mm long; the reciprocating sliding tuning block (302) is 4~16 mm long, and 5mm wide and high. The coupling resonance structure (3) has an adjustment range of 4~16mm.

7. The real-time acoustic signature protection device based on acoustic metamaterials according to claim 6, characterized in that, The geometric parameters of the Mie resonance metamaterial unit (2) are as follows: the diameter of the central cavity (1) is 19.5 mm, the outer arc length of the fan-shaped shell (201) is 49.5 mm, the radial length of the resonant cavity (203) is 21 mm, the length of the slide rail (301) is 8 mm, and the length of the reciprocating sliding tuning block (302) is 8 mm, and the width and height are both 5 mm.

8. A method for preparing a real-time acoustic signature protection device based on acoustic metamaterials according to any one of claims 1 to 7, characterized in that, It is made into a single piece using photosensitive resin 3D printing.

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