Quantitative test method and system for transmission loss of shock absorbing material based on moving coil earphone

Abstract

Specifically, this invention relates to a method and system for quantifying the transmission loss of vibration damping materials based on a moving-coil microphone, comprising: Step S1, fixing the moving-coil microphone to an exciter using a rigid clamp, using its coil as the vibration pickup unit, and making the damping coil under test the only transmission path; Step S2, removing the damping coil, outputting a burst random signal for frequency sweep to obtain a reference voltage; inserting the damping coil, and sweeping the frequency again to obtain the response voltage; Step S3, calculating the transmission loss TL(f); Step S4, extracting the resonant frequency f0 and half-power bandwidth Δf from the TL curve to obtain the damping ratio ζ, and inverting the stiffness k by combining the equivalent mass m of the microphone. This simplifies the damping coil into a single-degree-of-freedom forced vibration system. The advantages of this invention are: by utilizing the moving-coil microphone's own coil as the vibration pickup unit to eliminate the mass load effect of external sensors, and calculating the transmission loss curve based on the voltage ratio under dual-state frequency sweep, the objective quantification of the vibration attenuation characteristics of the vibration damping material and the inversion extraction of physical parameters such as stiffness and damping are achieved.

Description

Technical Field

[0001] This invention relates to the field of acoustic device testing technology, specifically to a method and system for quantifying the transmission loss of vibration damping materials based on dynamic microphone capsules. Background Technology

[0002] Dynamic microphones are widely used in performances, broadcasting, and recording due to their durability and lack of power consumption. However, because their transduction principle is based on electromagnetic induction, the relative motion between the voice coil and the magnetic circuit system not only generates sound signals but also induces noise caused by mechanical vibrations (i.e., structure-transmitted sound). When the microphone is subjected to hand-held friction, bracket conduction, or drop impact, the vibrational energy is transmitted through the outer shell to the internal dynamic microphone capsule. Without effective isolation, the diaphragm or voice coil inside the capsule will undergo unexpected displacement, resulting in a severe low-frequency "rumbling" sound in the output signal, seriously affecting audio quality. Vibration-damping coils and internal damping materials are key components for blocking such vibrations.

[0003] Current technologies for evaluating vibration damping coil performance have significant shortcomings. First, the industry generally relies on manual "tapping tests" or "handheld listening tests," the evaluation results of which are heavily influenced by the experience of the testers, cannot be quantified, and make it difficult to standardize quality control. Second, traditional vibration tests focus primarily on the frequency response of the dynamic microphone or the entire system, lacking independent analysis of the specific transmission link of "vibration source - damping material - sensitive element (dynamic microphone)." Furthermore, existing methods struggle to accurately isolate the physical parameters of the damping material itself (such as resonant frequency, damping coefficient, and attenuation slope), forcing designers to rely on experience and repeatedly test molds, resulting in long development cycles and high costs.

[0004] If an external vibration sensor (such as a piezoelectric accelerometer) is attached to the microphone housing to measure the vibration isolation effect, an additional sensor mass load will be introduced. A typical sensor mass of 3g-20g will alter the equivalent mass of the system, resulting in a lower measured resonant frequency and data distortion. Furthermore, the coupling interface between the sensor and the housing itself will introduce additional high-frequency damping peaks, causing significant installation artifacts in the measured attenuation curve. Another approach is to perform acoustic output spectrum analysis after hand-tapping the entire device; however, this method overlays the acoustic response of the damping coil, the housing structure, the internal air ducts, and even the diaphragm, making it impossible to isolate the resonant frequency and damping ratio of the damping coil itself.

[0005] Therefore, there is an urgent need for an objective, quantitative, and reproducible testing method to address the aforementioned technical bottlenecks. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method and system for quantitative testing of transmission loss of vibration damping materials based on a moving coil microphone. This method utilizes the moving coil microphone itself as a vibration pickup unit to eliminate the mass load effect of external sensors and calculates the transmission loss curve based on the voltage ratio under dual-state frequency sweep, thereby achieving objective quantification of the vibration attenuation characteristics of vibration damping materials and inversion extraction of physical parameters such as stiffness and damping.

[0007] To achieve the above objectives, a quantitative testing method for the transmission loss of vibration damping materials with a self-inductive moving coil microphone head is designed, including the following steps: S1. Constructing a zero-mass load test link: The moving coil microphone head is fixed to the driving exciter using a rigid clamp, and the coil of the moving coil microphone head itself is used as the vibration pickup unit, making the path through the vibration damping coil under test on the moving coil microphone head the only vibration transmission path; S2. Dual-state calibration: With the vibration damping coil under test removed, a burst random signal is output to the driving exciter using a signal acquisition and analysis module as excitation, and a full-band frequency sweep is performed to obtain the reference voltage curve Vref(f); with the vibration damping coil under test installed, the same full-band frequency sweep is performed to obtain the response voltage curve Vmic(f); S3. Calculating dimensionless transmission loss: The vibration attenuation characteristics of the vibration damping coil under test at each frequency point are calculated using the following formula: TL(f) = 20log 10 (Vref(f) / Vmic(f)), where TL(f) represents the vibration damping characteristic curve; S4. Physical parameter inversion: Based on the vibration damping characteristic curve, extract the resonant frequency f0 and half-power bandwidth Δf, calculate the damping ratio ζ using the formula ζ=Δf / (2f0), and invert the stiffness parameter k=m(2πf0) of the shock absorber to be tested by combining the equivalent mass m of the moving coil advance. 2 By simplifying the vibration damper under test into a single element with stiffness k and damping ζ, the vibration damper under test and the mass m of the moving coil's mouthpiece together form a single-degree-of-freedom forced vibration system, thereby establishing the mechanical model of the vibration damper under test.

[0008] Preferably, the present invention further includes: the parameters of the burst random signal in step S2 are: frequency range 20Hz~1000Hz, burst length 0.5s, burst period 1.0s, averaging number of times not less than 20, and window function is Hanning window; the signal acquisition and analysis module performs coherent averaging on the frequency response function acquired from multiple bursts, and calculates the coherent function γ 2 (f) Frequency points with a value of less than 0.9 were removed.

[0009] Preferably, the present invention further includes: step S2 further includes anisotropy testing: by rotating a rigid clamp, sweeping vibrations are applied to the axial and radial directions of the moving coil microphone head to obtain the attenuation difference of the damping coil under test in different directions.

[0010] Preferably, the present invention further includes: the rigid fixture and the test fixture are made of non-magnetic metal material, and an insulating gasket is provided between the fixture and the exciter table to avoid interference with the magnetic field of the moving coil microphone and to ensure the connection rigidity; the rigid fixture is provided with multiple detachable and replaceable adapter rings, the inner diameter of which is configured to match the outer diameter of different specifications of moving coil microphones, so as to realize the compatibility test of multiple microphone models.

[0011] Preferably, the present invention further includes: the resonant frequency f0 is obtained by directly reading the frequency coordinate corresponding to the peak amplitude in the vibration attenuation characteristic curve TL(f); the half-power bandwidth Δf is obtained by finding two frequency points on the TL(f) curve where the amplitude drops by 3dB on both sides of the peak (i.e., the square root of the peak amplitude) and calculating the difference between the two.

[0012] Preferably, the present invention further includes: in step S4, the equivalent mass m of the moving coil advance is a preset known parameter; based on the TL(f) curve, the resonant frequency f0 and the half-power bandwidth Δf are automatically extracted using the half-power bandwidth method to invert and obtain the stiffness parameter k and damping ratio ζ of the vibration isolator to be tested. The inversion is performed by directly substituting the extracted resonant frequency f0, half-power bandwidth Δf, and the known equivalent mass m of the moving coil advance into the classical vibration formulas ζ=Δf / (2f0) and k=m(2πf0). 2 It is obtained through computation, rather than through additional iterative algorithms or simulation fitting.

[0013] Preferably, the present invention further includes: the signal acquisition and analysis module uses a differential balanced input method to acquire the response voltage signal of the moving coil microphone head in order to suppress common-mode interference.

[0014] A quantitative testing system for the transmission loss of vibration damping material in a dynamic coil microphone head, employing the aforementioned testing method, includes: a driving exciter for providing controllable mechanical vibration and receiving a burst random signal as input excitation; a rigid fixture including a microphone head support for fixing the dynamic coil microphone head and a damping ring mounting interface for mounting the damping ring, forming a vibration transmission path through the displacement of the damping ring under test, and the rigid fixture is provided with multiple detachable and replaceable adapter rings, the inner diameter of which is configured to match the outer diameter of dynamic coil microphone heads of different specifications; and a signal acquisition and analysis module for outputting a burst random sweep frequency signal to the driving exciter, acquiring the response voltage of the dynamic coil microphone head to calculate the TL(f) curve, and inverting the resonant frequency f0, damping ratio ζ, and stiffness parameter k using the half-power bandwidth method.

[0015] Preferably, the present invention further includes: the parameters of the burst random signal output by the signal acquisition and analysis module are: frequency range 20Hz~1000Hz, burst length 0.5s, burst period 1.0s, averaging number not less than 20, and window function is Hanning window; the signal acquisition and analysis module performs coherent averaging on the frequency response function of multiple burst acquisitions, and sets the coherent function γ 2 (f) Frequency points with a value of less than 0.9 were removed.

[0016] Preferably, the present invention further includes: the rigid fixture and the testing fixture are made of non-magnetic metal material, and an insulating gasket is provided between the fixture and the exciter table; the rigid fixture applies sweep frequency vibration to the axial and radial directions of the moving coil head by rotational installation to obtain the attenuation difference of the test damping coil in different directions.

[0017] Compared with the prior art, the advantages of this invention are: By constructing a zero-mass-load test link and utilizing the dynamic coil's own coil as the vibration pickup unit, replacing traditional external accelerometers or laser vibrometers, this fundamentally eliminates the alteration of the equivalent mass of the tested system by the added sensor mass. It avoids the resonant frequency test value deviation caused by mass load and the high-frequency vibration attenuation artifacts introduced by the sensor-shell coupling interface, ensuring that the measured transmission loss curve truly reflects the vibration attenuation characteristics of the damper itself. Through a dual-state calibration process involving the removal and installation of the damper, reference voltage curves and response voltage curves are obtained under the same excitation energy. The dimensionless transmission loss curve is then calculated using formulas, transforming the traditional subjective evaluation relying on manual tapping or handheld listening into an objective, quantifiable data curve. This eliminates the influence of human experience on the test results, allowing for unified data benchmarking of damper performance from different batches and manufacturers, significantly improving quality control consistency. Based on the transmission loss curve, the resonant frequency and half-power bandwidth are automatically extracted using the half-power bandwidth method, and the damping ratio is then calculated. Combined with the equivalent mass inversion of the dynamic microphone head, the stiffness parameters of the damping coil are obtained. This achieves precise extraction and quantification of key physical parameters of the damping material, allowing engineers to determine whether the damping coil's stiffness matches the microphone head mass without relying on repeated trial moldings. Furthermore, the required material hardness and structural dimensions can be derived in reverse, significantly shortening the R&D cycle. By applying sweeping vibrations to the axial and radial directions of the dynamic microphone head using a rotating rigid fixture, the attenuation and stiffness differences of the damping coil in different directions can be obtained, providing a quantitative means for evaluating the performance of anisotropic materials. The rigid fixture uses non-magnetic metal materials and incorporates insulating gaskets to avoid interference from electromagnetic eddy currents on the microphone head's magnetic field. Simultaneously, multiple detachable and replaceable adapter rings on the fixture can accommodate different sizes of dynamic microphone head outer diameters, giving the testing system broad versatility and covering the testing needs of various microphone head models, from miniature lavalier microphones to large stage microphones. The coherent averaging mechanism of burst random signals effectively suppresses nonlinear distortion products, ensuring that the testing process satisfies the linear system assumption and guaranteeing the mathematical basis for subsequent parameter inversion calculations. The stiffness and damping parameters obtained from the inversion can be directly imported into finite element simulation software for virtual iterative design of the shock absorber ring, further improving R&D efficiency and reducing trial and error costs. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the signal acquisition and analysis module of the present invention; Figure 2 This is a schematic diagram of the power amplifier of the present invention; Figure 3 This is a schematic diagram of the vibrator of the present invention; Figure 4 These are before-and-after comparison curves of quantitative testing of the vibration damping material for a moving-coil microphone. A represents the reference voltage curve without a vibration damper, and B represents the response voltage curve with a vibration damper. In the diagram: 1 Signal acquisition and analysis module, 2 Power amplifier, 3 Exciter, 4 Fixture, 5 Vibration damper, 6 Voice capsule. Detailed Implementation

[0019] To make the purpose, principle and structure of the present invention clearer, the following description is provided in conjunction with the accompanying drawings and specific embodiments.

[0020] like Figures 1 to 4 As shown, this embodiment provides a method and system for quantitative testing of vibration damping material transmission loss based on a moving-coil microphone. Figure 1 A schematic diagram of signal acquisition and analysis module 1 is shown. This module is used to output a sweep frequency excitation signal and acquire the response voltage signal. Figure 2 A schematic diagram of power amplifier 2 is shown, which is used to amplify the electrical signal output by signal acquisition and analysis module 1 to drive the exciter; Figure 3 A schematic diagram of the exciter 3 is shown, which serves as a vibration excitation source to provide controllable mechanical vibration for the entire test system; Figure 4 The curves before and after quantitative testing of the dynamic microphone head damping material are shown. Curve A represents the reference voltage curve Vref(f) measured without the damping coil, and curve B represents the response voltage curve Vmic(f) measured with the damping coil.

[0021] In practical implementation, step S1 is performed first, which involves constructing a zero-mass-load test link. The core of this step is to fix the moving-coil microphone 6 to the drive exciter 3 using a rigid clamp 4, completely eliminating the need for external accelerometers or laser vibrometers commonly used in traditional testing. Instead, the coil inherent in the moving-coil microphone 6 is used as the vibration pickup unit. Its working principle is based on Faraday's law of electromagnetic induction. When the coil of the moving-coil microphone 6 vibrates along with the microphone housing, the coil moves within the magnetic field of the microphone's internal magnetic circuit, cutting magnetic lines of force. This generates an induced electromotive force E=B·l·v at the ends of the coil, where B is the magnetic induction intensity, l is the effective length of the coil, and v is the vibration velocity of the coil relative to the magnetic field. Therefore, the induced electromotive force output by the coil is proportional to the vibration velocity. Thus, by measuring the voltage signal across the microphone coil, the vibration state of the microphone housing can be accurately reflected. Since the coil itself is an inherent component of the moving-coil microphone 6, using it as a vibration pickup sensor does not add any additional mass load to the system under test, fundamentally eliminating the mass load effect brought about by traditional external sensors. Based on this, this step also needs to ensure the uniqueness of the vibration transmission path. That is, after the vibration energy is output from the exciter 3, it is transmitted sequentially through the rigid clamp 4, the test damping ring 5, and finally to the moving coil tone head 6. There are no other bypass transmission paths. The rigid clamp 4 is designed to have sufficient structural rigidity and does not undergo significant structural resonance or deformation within the test frequency band, thereby ensuring the fidelity of vibration transmission. In the above way, step S1 constructs a closed-loop "electric-mechanical-electric" test link. That is, the signal acquisition and analysis module 1 outputs an electrical signal, which is converted into mechanical vibration by the exciter 3 driven by the power amplifier 2. The mechanical vibration is transmitted to the moving coil tone head 6 through the test damping ring 5. The moving coil tone head 6 then converts the vibration signal back into an electrical signal and sends it back to the signal acquisition and analysis module 1, thus forming a complete signal closed loop.

[0022] Then, step S2, the dual-state calibration process, is executed. This step is divided into two stages: the first stage is the baseline calibration with the damper 5 removed, and the second stage is the response test with the damper 5 installed. In both stages, the signal acquisition and analysis module 1 outputs a burst random signal with the same energy parameters to the drive exciter 3 as excitation, performing a full-band frequency sweep. The burst random signal is chosen because it combines the wideband characteristics of a random signal with the transient characteristics of a burst mode, enabling the system to excite all modes across the entire frequency band in a short time. Simultaneously, the burst mode allows sufficient decay time between two bursts, preventing residual vibrations from the previous excitation from affecting the subsequent measurement. Specifically, the parameters for the burst random signal in this step are preferably set as follows: frequency range of 20Hz to 1000Hz, which covers the low-frequency vibration region of greatest concern for dynamic microphone damping coils, as structural noise such as handheld friction and bracket conduction is usually concentrated in the low-frequency band below several hundred hertz; burst length is set to 0.5s, meaning each burst signal lasts for 0.5 seconds before being interrupted; burst period is set to 1.0s, meaning every 1.0 second contains a 0.5-second burst and a 0.5-second silence period; averaging is no less than 20 times, meaning at least 20 burst excitations and corresponding response acquisitions are performed for each test state, using multiple averaging to suppress the influence of random noise and nonlinear distortion products; a Hanning window is used to window the acquired time-domain signal to reduce spectral leakage. Signal acquisition and analysis module 1 performs a fast Fourier transform on the time-domain response signals acquired from multiple bursts to obtain the frequency response function of each burst, then performs coherent averaging on these frequency response functions, and simultaneously calculates the coherence function γ at each frequency point. 2 (f) The coherence function is an indicator that measures the degree of linear correlation between the input and output signals. Its value ranges between 0 and 1. When the coherence function value is close to 1, it indicates a good linear causal relationship between the input and output at that frequency point. Conversely, when the coherence function value is low, it indicates strong nonlinear interference or noise pollution at that frequency point. In this embodiment, the coherence function γ... 2 (f) Frequency data with a value of less than 0.9 were removed to ensure that all frequency data used in subsequent calculations met the linear system assumption, thus guaranteeing the mathematical basis for parameter inversion calculations.

[0023] In the first stage, with the damper 5 removed, the moving coil advance 6 is directly fixed to the platform of the exciter 3 via the rigid clamp 4. At this time, there are no damping or vibration isolation elements in the vibration transmission path, and the vibration energy generated by the exciter 3 is transmitted to the moving coil advance 6 almost without loss. Therefore, the voltage signal output by the moving coil advance 6 represents the reference level of the input vibration, denoted as Vref(f). In the second stage, with the damper 5 installed, the damper 5 to be tested is installed between the rigid clamp 4 and the moving coil advance 6. At this time, the damper 5 to be tested is added to the vibration transmission path. The vibration energy generated by the exciter 3 is attenuated by the damper 5 before being transmitted to the moving coil advance 6. Therefore, the voltage signal output by the moving coil advance 6 represents the vibration level after attenuation by the damper 5, denoted as Vmic(f). The input excitation energy of the exciter 3 is kept completely consistent in both stages, so the only difference between Vref(f) and Vmic(f) comes from the vibration transmission characteristics of the damper 5. Furthermore, to comprehensively evaluate the vibration damping performance of the damping ring 5 in different directions, this step also includes an anisotropic test. Specifically, by rotating the rigid clamp 4, sweep vibrations are applied to the axial (Z-axis) and radial (X / Y-axis) directions of the moving coil head 6. After completing the axial test, the rigid clamp 4, along with the moving coil head 6 and the damping ring 5 fixed to it, is rotated 90 degrees and refixed to the exciter 3 platform, aligning the original radial direction with the vibration output direction of the exciter 3. This allows the damping characteristic curve of the damping ring 5 in the radial direction to be obtained. For damping rings 5 ​​made of anisotropic materials, their stiffness and damping characteristics in the axial and radial directions often differ significantly. This step quantifies these differences as data curves, providing a technical means for evaluating the performance of anisotropic damping materials. The rigid fixture 4 and the testing fixture are both made of non-magnetic metal materials such as aluminum alloy or stainless steel to avoid interference from ferromagnetic materials on the magnetic field distribution of the internal magnetic circuit of the dynamic microphone 6. Insulating gaskets are placed between the rigid fixture 4 and the exciter 3 platform to cut off any potential ground loops and prevent eddy currents induced on the exciter 3 platform from being conducted to the dynamic microphone 6 through the fixture 4, thus preventing electromagnetic interference. Furthermore, the rigid fixture 4 is equipped with multiple detachable and replaceable adapter rings. The inner diameter of these adapter rings is configured to match the outer diameter of dynamic microphones 6 of different sizes, allowing the same testing system to be compatible with the testing needs of dynamic microphones 6 of various shapes and sizes, from miniature lavalier microphones to large stage microphones.

[0024] After completing the two-state calibration and obtaining the reference voltage curve Vref(f) and the response voltage curve Vmic(f), step S3 is executed, which calculates the dimensionless transmission loss. This step calculates the vibration attenuation characteristics of the tested shock absorber 5 at various frequencies using the following formula: TL(f) = 20log 10(Vref(f) / Vmic(f)). The physical meaning of this formula is that the reference voltage Vref(f) without the damper is used as the reference, and the response voltage Vmic(f) with the damper is used as the measured response. The ratio of the two is taken as the common logarithm and multiplied by 20 to obtain the transmission loss value in decibels. According to Faraday's law of electromagnetic induction, the voltage output of the moving coil advance 6 is proportional to the vibration velocity, and the square of the vibration velocity is proportional to the vibration energy. Therefore, the logarithmic form of the voltage ratio directly maps the attenuation of vibration energy. When Vref(f) is greater than Vmic(f) at a certain frequency, TL(f) is positive, indicating that the damping coil 5 has a damping effect on the vibration at that frequency. The larger the positive value, the more significant the damping effect. Conversely, if Vref(f) is less than Vmic(f) at a certain frequency, that is, TL(f) is negative, it means that the damping coil 5 actually amplifies the vibration transmission at that frequency. This usually occurs near the resonance frequency of the system formed by the damping coil 5 and the moving coil advance 6. At this time, the elastic element of the damping coil 5 and the inertial mass of the moving coil advance 6 resonate and couple, and the vibration energy is enhanced rather than attenuated at the resonance point. The TL(f) curve obtained in this way fully reflects the vibration damping characteristics of the tested damping coil 5 across the entire frequency range. The transmission loss curve is dimensionless, meaning it does not depend on the specific excitation amplitude, but only on the matching relationship between the physical characteristics of the damper coil 5 and the quality of the moving coil advance 6. Therefore, it has good repeatability and comparability. Damper coils 5 produced by different batches and different manufacturers can be directly quantified and benchmarked using the TL(f) curve obtained by this method.

[0025] The next step is step S4, which involves physical parameter inversion. This step is based on the TL(f) curve obtained in step S3, extracting two key characteristic parameters: the resonant frequency f0 and the half-power bandwidth Δf. Then, the damping ratio ζ and stiffness k of the damper coil 5 are calculated using classical vibration formulas. Specifically, the resonant frequency f0 is the frequency coordinate corresponding to the peak amplitude on the TL(f) curve. This frequency point is where the entire vibration system responds most intensely; it is the frequency at which the single-degree-of-freedom system composed of the damper coil 5 and the moving coil advance 6 resonates. In the TL(f) curve, the resonant frequency f0 often presents a significant peak because the damper coil 5 has the worst vibration damping effect, even exhibiting negative damping, at this frequency point. The half-power bandwidth Δf is defined as the difference between the two frequency points corresponding to a 3dB drop in amplitude on either side of the peak on the TL(f) curve. This 3dB drop refers to a 3dB decrease from the peak amplitude, i.e., the amplitude decreases to the square root of the peak amplitude, corresponding to a decrease in vibration energy to half of the peak energy; hence, it is called the half-power point. The damping ratio ζ is calculated using the half-power bandwidth method as ζ = Δf / (2f0). This formula is based on the frequency response function theory of a single-degree-of-freedom forced vibration system. When the system damping ratio is much less than 1, the above-mentioned linear relationship exists between the half-power bandwidth and the damping ratio. The damping ratio ζ reflects the ability of the damper coil 5 to dissipate vibration energy. A larger damping ratio indicates that the damper coil 5 can more quickly convert vibration energy into heat energy and dissipate it, thereby suppressing the continuous transmission of vibration more quickly. Based on this, combined with the equivalent mass m of the moving coil advance 6, the formula k = m(2πf0) is used. 2 The stiffness parameter k of the damper coil 5 under test is obtained through inversion. The equivalent mass m of the moving coil advance 6 is an inherent parameter of the moving coil advance 6 itself, which can be obtained directly through high-precision weighing or the manufacturer's specifications. The stiffness parameter k reflects the hardness of the damper coil 5; the larger the k value, the harder the damper coil 5 is, and the greater the elastic restoring force it can generate under the same vibration displacement. Through the above inversion calculation, the damper coil 5 under test is simplified into a single elastic damping element with stiffness k and damping ratio ζ, which, together with the equivalent mass m of the moving coil advance 6, forms a classic single-degree-of-freedom forced vibration system. The establishment of this mechanical model reduces the originally complex problem of damper coil performance evaluation to a vibration system problem that can be fully described by only two parameters, namely stiffness k and damping ratio ζ. Engineers can directly determine whether the stiffness and damping characteristics of the damper coil 5 match the current advance mass based on these two parameters, and deduce the required material hardness and structural dimensions accordingly, enabling targeted design and optimization without repeated trial molding.

[0026] In the implementation of the above method, the signal acquisition and analysis module 1 uses differential balanced input to acquire the response voltage signal of the moving coil tone head 6. Differential balanced input can effectively suppress common-mode interference. That is, when external electromagnetic interference acts on both ends of the signal line with the same amplitude and phase, the differential amplifier only amplifies the difference signal at both ends and suppresses the common-mode signal, thereby ensuring that the acquired response voltage signal has a high signal-to-noise ratio and avoiding the influence of electromagnetic noise in the test environment on the measurement accuracy.

[0027] The following is a complete description of the above test process through a specific embodiment. First, the test system is set up. The signal output terminal of the signal acquisition and analysis module 1 is connected to the input terminal of the power amplifier 2, and the output terminal of the power amplifier 2 is connected to the drive coil of the drive exciter 3. The rigid fixture 4 is fixed to the platform of the drive exciter 3. The moving coil microphone 6 to be tested is installed in the rigid fixture 4 through the matching adapter ring, and the signal output terminal of the moving coil microphone 6 is connected to the differential balanced input terminal of the signal acquisition and analysis module 1. At the start of the test, the vibration damper 5 was not installed. In the signal acquisition and analysis module 1, the parameters for the burst random signal were set as follows: frequency range 20Hz to 1000Hz, burst length 0.5s, burst period 1.0s, averaging count 20, and Hanning window function. Then, frequency sweep was initiated. The signal acquisition and analysis module 1 output the aforementioned burst random signal, which was amplified by the power amplifier 2 and used to drive the exciter 3 to generate mechanical vibration. The response voltage signal output by the moving coil tone head 6 was fed back to the signal acquisition and analysis module 1 via differential balanced input. The signal acquisition and analysis module 1 performed coherent averaging on the frequency response function acquired from the 20 bursts, discarding the coherent function γ. 2 After obtaining frequency data where (f) < 0.9, the reference voltage curve Vref(f) is obtained. Then, the shock absorber 5 to be tested is installed, and the parameter settings of the signal acquisition and analysis module 1 are kept completely unchanged. A burst random frequency sweep with the same energy is performed again to obtain the response voltage curve Vmic(f). The signal acquisition and analysis module 1 calculates the response voltage curve Vmic(f) according to the formula TL(f) = 20log 10 The TL(f) curve is automatically calculated using (Vref(f) / Vmic(f)). On the TL(f) curve, the system automatically finds the peak amplitude and its corresponding frequency coordinate as the resonant frequency f0. Then, it searches for two frequency points on both sides of the peak where the amplitude drops by 3dB and calculates the difference between them as the half-power bandwidth Δf. This completes the quantitative extraction of all key physical parameters of the damper coil 5. If the entire device is rotated 90 degrees and tested again, the resonant frequency, damping ratio, and stiffness parameters in the radial direction can be obtained. By comparing the differences between the axial and radial parameters, it can be determined whether the damper coil 5 has anisotropic vibration isolation characteristics.

[0028] Through the above specific implementation methods, the method and system provided in this application can transform the traditional performance evaluation process of the shock absorber ring, which relies on subjective listening and human experience, into an objective, quantitative, and automated testing process. The obtained TL(f) curve and the inverted physical parameters such as stiffness k and damping ratio ζ can be used for quality control inspection of the shock absorber ring 5, or directly imported into finite element simulation software for virtual iterative design and optimization of the shock absorber ring 5.

[0029] The above description is merely a specific embodiment of the invention, but the scope of protection of the invention is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the invention, based on the technical solution and concept of the invention, should be covered within the scope of protection of the invention.

Claims

1. A method for quantitatively testing the transmission loss of vibration damping materials based on moving-coil advance, characterized in that, Includes the following steps: S1. Construct a zero-mass load test link: Fix the moving coil microphone to the drive exciter with a rigid clamp, use the moving coil microphone's own coil as the vibration pickup unit, and make the path through the test damping coil on the moving coil microphone the only vibration transmission path; S2. Dual-state calibration: With the shock absorber removed, a burst random signal is output to the drive exciter using the signal acquisition and analysis module as excitation, and a full-band frequency sweep is performed to obtain the reference voltage curve Vref(f); with the shock absorber installed, the same full-band frequency sweep is performed to obtain the response voltage curve Vmic(f). S3. Calculate dimensionless transmission loss: Obtain the vibration attenuation characteristics of the shock absorber at various frequencies using the following formula: TL(f) = 20log 10 (Vref(f) / Vmic(f)), where TL(f) represents the vibration damping characteristic curve; S4. Physical parameter inversion: Based on the vibration attenuation characteristic curve, the resonant frequency f0 and half-power bandwidth Δf are extracted. The damping ratio ζ is calculated using the formula ζ=Δf / (2f0). Combined with the equivalent mass m of the moving coil advance, the stiffness parameter k=m(2πf0) of the shock absorber under test is obtained. 2 ; By simplifying the vibration damper under test into a single element with stiffness k and damping ζ, the vibration damper under test and the mass m of the moving coil's mouthpiece together form a single-degree-of-freedom forced vibration system, thereby establishing the mechanical model of the vibration damper under test.

2. The method for quantitatively testing the transmission loss of vibration damping materials based on a moving-coil advance mechanism as described in claim 1, characterized in that, In step S2, the parameters of the burst random signal are: frequency range 20Hz~1000Hz, burst length 0.5s, burst period 1.0s, averaging number of bursts not less than 20, and Hanning window function. The signal acquisition and analysis module performs coherent averaging on the frequency response function acquired from multiple bursts and sets the coherent function γ... 2 (f) Frequency points with a value of less than 0.9 were removed.

3. The method for quantitatively testing the transmission loss of vibration damping materials based on a moving-coil advancer as described in claim 1, characterized in that, Step S2 also includes anisotropy testing: by rotating a rigid clamp, sweep vibrations are applied to the axial and radial directions of the moving coil advance to obtain the attenuation differences of the damping coil under test in different directions.

4. The method for quantitatively testing the transmission loss of vibration damping materials based on a moving-coil advancer as described in claim 1, characterized in that, The rigid fixture and test tooling are made of non-magnetic metal material, and an insulating gasket is provided between the fixture and the exciter table to avoid interference with the magnetic field of the moving coil head and to ensure the connection is rigid. The rigid fixture is equipped with multiple detachable and replaceable adapter rings. The inner diameter of the adapter rings is configured to match the outer diameter of different sizes of moving coil capsules, so as to achieve compatibility testing of multiple capsule models.

5. The method for quantitatively testing the transmission loss of vibration damping materials based on a moving-coil advance mechanism as described in claim 1, characterized in that, The resonant frequency f0 is obtained by directly reading the frequency coordinate corresponding to the peak amplitude in the vibration decay characteristic curve TL(f); The half-power bandwidth Δf is obtained by finding two frequency points on the TL(f) curve where the amplitude drops by 3dB on both sides of the peak (i.e., the square root of the peak amplitude) and calculating the difference between them.

6. The method for quantitatively testing the transmission loss of vibration damping materials based on a moving-coil advancer as described in claim 1, characterized in that, In step S4, the equivalent mass m of the moving coil advance is a preset known parameter. Based on the TL(f) curve, the resonant frequency f0 and half-power bandwidth Δf are automatically extracted using the half-power bandwidth method to invert and obtain the stiffness parameter k and damping ratio ζ of the vibration isolator to be tested. The inversion is performed by directly substituting the extracted resonant frequency f0, half-power bandwidth Δf and the known equivalent mass m of the moving coil advance into the classical vibration formulas ζ=Δf / (2f0) and k=m(2πf0). 2 It is obtained through computation, rather than through additional iterative algorithms or simulation fitting.

7. The method for quantitatively testing the transmission loss of vibration damping materials based on a moving-coil advance mechanism as described in claim 1, characterized in that, The signal acquisition and analysis module uses a differential balanced input method to acquire the response voltage signal of the moving coil microphone head in order to suppress common-mode interference.

8. A quantitative testing system for transmission loss of vibration damping materials based on a moving-coil advance mechanism, characterized in that, The test method described in any one of claims 1-7 includes: A drive exciter is used to provide controllable mechanical vibration and receives burst random signals as input excitation. The rigid fixture includes a head carrier for fixing the moving coil head and a damper mounting interface for mounting the damper, forming a vibration transmission path through the displacement of the damper under test. The rigid fixture is provided with multiple detachable and replaceable adapter rings, the inner diameter of which is configured to match the outer diameter of moving coil heads of different specifications. The signal acquisition and analysis module is used to output a burst random sweep frequency signal to drive the exciter, acquire the response voltage of the moving coil advance to calculate the TL(f) curve, and invert the resonance frequency f0, damping ratio ζ and stiffness parameter k by using the half-power bandwidth method.

9. The vibration damping material transmission loss quantification test system based on a moving-coil microphone as described in claim 8, characterized in that, The parameters of the burst random signal output by the signal acquisition and analysis module are: frequency range 20Hz~1000Hz, burst length 0.5s, burst period 1.0s, averaging number of times not less than 20, and Hanning window function; the signal acquisition and analysis module performs coherent averaging on the frequency response function of multiple burst acquisitions, and calculates the coherence function γ 2 (f) Frequency points with a value of less than 0.9 were removed.

10. The vibration damping material transmission loss quantification test system based on a moving-coil advance pin as described in claim 8, characterized in that, The rigid fixture and testing tooling are made of non-magnetic metal material, and an insulating gasket is provided between the fixture and the exciter table. The rigid fixture applies sweep frequency vibration to the axial and radial directions of the moving coil head by rotating the installation method to obtain the attenuation difference of the test damping coil in different directions.

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