38 results about "Free field" patented technology

The invention belongs to the technical field of acoustics, and particularly relates to an index type open-pore rigid plate internal vector sound field calculation method, program and equipment and a storage medium. According to a Webster equation satisfied by a simple harmonic plane sound source excitation sound pressure field, circular piston radiation acoustic impedance on an infinite baffle plate is adopted to represent radiation impedance at an opening of an exponential open pore, a sound field analytical solution of any depth in the open pore of the exponential open pore rigid plate is constructed, system calculation is carried out in combination with sound source conditions, and a sound field of any depth in the open pore of the exponential open pore rigid plate is obtained. Therefore, sound field quantities such as internal accurate sound pressure and vibration velocity of the exponential type open-pore rigid plate under the vertical incidence condition can be quickly solved, and sound field distribution conditions under different section change rules and different open-pore rigid plate sizes can be calculated. According to the method, the calculation complexity is low, the influence problem caused by sound field changes under the non-free field condition can be solved, and the calculation stability and reliability under the complex boundary condition are ensured.

The invention discloses a reservoir water fluctuation propagation direct numerical simulation method and device in gravity dam anti-seismic analysis, a medium and equipment. According to the method, fluctuation propagation in reservoir water under combined incidence of P waves and SV waves is considered, a reservoir water-foundation site free field is analyzed and calculated on the basis of the fluctuation theory and the potential function theory, then the site free field is converted into node counterforce on fluid and solid boundaries on the basis of a fluid and solid power artificial boundary substructure model, and the reservoir water-foundation site free field is obtained. Applying node counterforce on the reservoir water-foundation artificial boundary, and directly performing numerical simulation on reservoir water-foundation site free field response; based on a static-dynamic artificial boundary conversion method, considering the influence of the static effect of the gravity dam-reservoir water-foundation system on the dynamic effect of the system, and constructing a gravity dam seismic oscillation input model for directly simulating reservoir water fluctuation propagation; according to the method, the anti-seismic analysis precision of the gravity dam is improved, and the limitations of single-wave incidence during reservoir water fluctuation propagation simulation, failure to consider the static effect and the like are overcome.

The invention provides a near-fault site multi-seismic-phase free field inversion method based on sphere / cylindrical diffusion characteristics, and a research system in the field of near-fault inversion is perfected. On the basis of spherical diffusion characteristics of body waves and cylindrical diffusion characteristics of surface waves, a near-fault site multi-seismic-phase free field inversion framework is constructed by adopting a dynamic stiffness matrix method, and an inversion problem is converted into a multi-target optimization problem for solving an epicentral distance and a seismic source depth; on the basis, the space-time difference of the free field displacement waveform is quantified by adopting a dynamic regular path distance, and a target function is constructed by taking the minimization of the three-dimensional displacement waveform difference of two similar points as a criterion; meanwhile, constraint conditions are set in combination with propagation attenuation characteristics of seismic waves, so that a near-fault inversion multi-objective optimization model is established; and then, a rapid non-dominated multi-objective genetic algorithm is introduced to solve a Pareto optimal solution of an optimization variable, and the optimal solution is substituted into an inversion framework to complete multi-seismic-phase free field inversion of the near-fault site.

The invention relates to the technical field of geotechnical engineering, in particular to a sandy soil liquefaction discrimination method which comprises the following steps: collecting geological survey data, seismic parameters and soil test and in-situ test results of a target area, and determining parameters required by numerical simulation; a three-dimensional calculation model is constructed, grids are subdivided, a constitutive model is set, static balance and an initial pore pressure field are established, and the accuracy of the model is verified through mechanical balance and fluid balance; dynamic waves are processed and applied, a free field boundary, a seepage mode and mechanical damping are set, a coupling constitutive model is constructed, and monitoring points are arranged on the liquefiable stratum; determining liquefaction according to the effective stress, the pore water pressure time history curve and the excess pore pressure ratio; according to the invention, vertical and lateral deformation after liquefaction can be predicted, quantitative deformation data can be provided, errors of a standard penetration test are reduced, and the problems of small application range and strong regionality are solved; and the judgment result is more accurate through the verification of the excess pore pressure ratio, and a reliable basis is provided for the design of engineering anti-liquefaction measures.

A multi-mode surface-wave free-field inversion method based on dispersion properties of layered media addresses the inaccuracy in existing methods that ignore higher modes. A novel approach for characterizing the participation quantity of each mode is proposed based on an energy flux density, which is applied to calculate a modal participation factor through dispersion curves and the frequency-domain dynamic stiffness matrix. Next, the ground surface-wave components with dispersion properties are transferred from the time domain to the frequency domain and decomposed into harmonic components composed of individual frequencies by the Fast Fourier Transform technology. These harmonic components continue to be decoupled as multiple modes by the modal participation factors, with each single-mode component being inverted to construct single-mode surface-wave free fields. Finally, all single-mode surface-wave free fields are superimposed following the mode superposition principle to form the multi-mode surface-wave free fields.

In the present invention, an earthquake detection system based on the combination configuration of a free field and remote signal source is provided. The earthquake detection system includes: a host; a main sensor arranged in a free field and connected to the host; and a plurality of backup sensors, which are remotely arranged with respect to the main sensor, wherein each of the backup is connected to the host via the internet and transmits a remote signal to the host so as to avoid misjudging the occurrence of earthquakes because of unnatural factors, and prevent the vibration caused by human activities from interfering with the detector. The earthquake detection system achieves the effect of verification through a plurality of sensors installed in different positions. Only when all the sensors confirm that there is an earthquake, an earthquake warning will be issued to the protected place, and two sensors set in different environments can be used to avoid the deficiency that the two sensors misjudge at the same time due to the same kind of interference that the two sensors may receive in the same environment.

The invention discloses a method and system for calculating a seismic oscillation amplification coefficient of a river valley field under SV wave incidence, and belongs to the technical field of rock-soil seismic engineering, and the method comprises the steps: building a model; analyzing an infinitesimal body; establishing a free field; establishing a scattering field; substituting boundary conditions; solving a matrix equation; and calculating an amplification coefficient. According to the method, a wave field caused by an irregular terrain of the earth surface is constructed by an interval decomposition strategy taking a terrain cuspidal point as a demarcation point, a method for calculating the seismic oscillation amplification coefficient of the river valley field under SV wave incidence is provided, and the influence of factors such as river valley geometric parameters, material parameters, the frequency and incident angle of incident waves and the like on the river valley seismic oscillation amplification coefficient is revealed; a theoretical basis is provided for aseismic design of major projects of river valleys; the calculation method is a semi-analytical method, reveals the physical nature of irregular terrains on seismic wave propagation and scattering, improves the calculation precision and efficiency, and can be used as a reference for verification of a numerical method.

The present application belongs to the field of sound field reconstruction and sound source identification technology, and discloses an equivalent source sound field positioning method and system based on sparse sound intensity measurement, which acquires the complex sound pressure and complex particle velocity at the measurement point on the holographic surface through a vector sensor array, and calculates the measured sound intensity vector; constructs a sound intensity transfer matrix based on the equivalent source method, establishes a linear measurement equation between the measured sound intensity vector and the equivalent source intensity vector; by using the spatial sparsity of the equivalent source intensity, the solving of the equivalent source intensity vector is converted into an L1 norm sparse optimization problem, and a convex optimization algorithm is used to solve it to obtain the optimal equivalent source intensity vector; based on the optimal equivalent source intensity vector, the acoustic quantity at any point in the target sound field is reconstructed by combining the free field Green function. The present application uses the active component of the sound intensity vector to suppress non-related noise, improves the ill-conditioned inversion by combining the compressive sensing theory, and can realize high robustness and high precision sound source positioning and sound field reconstruction without reference microphones.

The invention provides a workshop floor response spectrum calculation method adopting substructure analysis, and the method comprises the steps: solving a site response problem of a free field through a semi-analytical method based on the modulus and damping of the free field, and obtaining transmission boundary information; respectively calculating foundation impedance matrixes of transmission boundary information through a flexible volume method; calculating an upper structure matrix according to the foundation impedance matrix; the upper structure matrix comprises an upper stiffness matrix, an upper mass matrix and an upper damping matrix; constructing a motion equation according to the foundation impedance matrix and the upper structure matrix, and solving to obtain a frequency domain displacement response transfer function; and performing interpolation calculation on the frequency domain displacement response transfer function to obtain seismic response. According to the method, the calculation of the reaction spectrum is realized through a substructure analysis method for decomposing a linear soil-junction interaction analysis problem into a series of relatively simple subproblems, the calculation efficiency is improved, and the model construction period is shortened.

The invention discloses a weighted error prediction-based long and thin space de-reverberation method, which fully considers the characteristics of an underwater long and thin space, considers the conditions of underwater sound wave attenuation and wall surface sound reflection, and calculates the influence of reverberation generated by sound sources at different positions on measurement points at different positions by using a mirror image method. And then extracting a theoretical part for removing reverberation in the weighted error prediction method, transforming the theoretical part, and processing reverberation signals in a frequency domain by frequency bands to form a set of sound pressure level measurement method suitable for the reverberation environment of the underwater slender space. Through simulation verification, the sound pressure level in a reverberation field is increased by 20dB relative to a free field, and the maximum difference between the sound pressure level of each frequency band of a one-third octave obtained after reverberation removal and the sound pressure level of the free field is within 4dB.

The invention belongs to the technical field of acoustic measurement, and discloses a free space sound field measurement method and system, and the method comprises the steps: constructing a free light path sound field measurement system based on a Michelson interferometer principle; acquiring a reference image, introducing a sound field to be measured, and controlling a loudspeaker or a laser beam to perform translation and rotary scanning through a computer to complete interference pattern data acquisition; preprocessing the acquired interference pattern, identifying the edge of the interference fringes by using an edge detection technology, and carrying out light phase variation calculation; and performing sound field reconstruction by adopting a Radon inverse transformation algorithm, converting sound field integral information carried by a laser beam into a sound pressure value of each point in a real space, and reconstructing a free field sound pressure distribution diagram. The method has the advantages of no damage and low cost, the measurement precision of the sound field and the integrity and reliability of reconstruction are remarkably improved, the nano-scale optical path change caused by the sound field can be effectively captured, and the high precision of sound field measurement and the accuracy of sound source recognition are ensured.

In order to solve the problems of large measurement error of acoustic performance in low frequency range and great difficulty in sample production of the existing pulse sound tube method and free field experiment measurement method for obtaining acoustic performance parameters of viscoelastic materials, the present application provides a prediction method from dynamic mechanical parameters under water pressure to acoustic performance of small samples, comprising the following steps: obtaining the calculation formula of the longitudinal wave speed and attenuation coefficient of viscoelastic materials according to the dynamic mechanical parameters of the viscoelastic materials under different water pressures; establishing an acoustic parameter prediction model of small samples based on a water sound tube and the viscoelastic materials, and solving the acoustic performance parameters of the small samples by the transfer matrix method; combining the calculation formula of the longitudinal wave speed and attenuation coefficient, the acoustic performance parameters of the small samples and the conversion relationship between the dynamic mechanical parameters, to obtain the conversion relationship between the dynamic mechanical parameters and the acoustic performance parameters of the small samples under different water pressures; and based on the conversion relationship, solving the acoustic performance prediction value according to the dynamic mechanical parameters.

This invention belongs to the technical field of low-frequency calibration methods for non-free-field hydrophones, and particularly relates to a low-frequency calibration method for non-free-field hydrophones based on multi-frequency measurement and deep learning. The method involves determining the test frequency points for hydrophone calibration, selecting several frequency points within the nearest frequency band of each test frequency point, emitting sinusoidal pulse signals through an underwater acoustic transducer, and receiving the acoustic signal waveforms corresponding to each frequency point at the sound pressure measurement point. The received waveforms at each frequency point are then time-domain aligned and resampled to construct a two-dimensional waveform diagram with time as the horizontal axis and frequency as the vertical axis. In this two-dimensional waveform diagram, the direct sound components are vertically distributed, while the reflected sound components are slopingly distributed with different slopes. A deep learning module based on a U-shaped encoder-decoder network structure is constructed, and this deep learning module is trained and its parameters optimized using a pre-generated two-dimensional waveform dataset.

The invention belongs to the field of rock-soil earthquake engineering, and particularly relates to a method for evaluating the anti-seismic performance of an end bearing pile in stratified soil under the action of earthquake S waves. According to the method, a pile-soil model is established on the basis of a continuous medium theory under a linear elastic frame, and displacement of a free field and a scattered field of a soil body is decoupled through a Helmholtz decomposition method; the soil layer boundary is processed by adopting the orthogonality of a modal function characteristic function, and the motion response of the pile foundation is described by adopting a strict closed form solution. Frequency domain amplitude-frequency characteristic analysis is adopted, a motion corresponding coefficient and a motion amplification coefficient are introduced to quantitatively evaluate the influence of the soil layer thickness and the soil layer rigidity ratio on the anti-seismic performance of the end bearing pile, and theoretical support is provided for pile foundation optimization design.

The invention relates to an air ultrasonic touch fingertip skin mechanical simulation method based on time domain BEM-FEM coupling, and belongs to the technical field of man-machine interaction and touch rendering. The method comprises the steps of constructing a piezoelectric ultrasonic transducer PUT array time domain sound field model, calculating focused ultrasonic waves of a PUT array in a free field and time domain sound field distribution of the focused ultrasonic waves, constructing a rigid body surface sound scattering model based on a time domain boundary element method BEM, and calculating synthetic ultrasonic waves after the focused ultrasonic waves are incident to the rigid body surface and time domain total sound field distribution of the synthetic ultrasonic waves; applying the solved time domain total sound field to sound radiation pressure ARP calculation; a three-dimensional fingertip model with a multilayer anatomical structure is established, and skin deformation of finger skin under air ultrasonic tactile stimulation is solved based on a finite element method FEM. The method has the advantages that mapping from driving waveform design of the air ultrasonic tactile device to finger skin deformation is achieved, and an efficient simulation method is provided for complex air ultrasonic tactile rendering.

The invention discloses a high-precision seismic fluctuation input method and device for SSI analysis of a layered stepped site, and the method comprises the steps: building a two-dimensional stepped layered site model, and introducing a Y-shaped artificial boundary to divide the two-dimensional stepped layered site model into a central finite field, a left half infinite field and a right half infinite field; applying a zigzag-paraxial combined boundary on the Y-shaped artificial boundary to simulate the radiation damping effect of the left half infinite domain and the right half infinite domain; respectively solving the seismic response of the one-dimensional horizontal layering field models of the left half infinite domain and the right half infinite domain, and obtaining the free field response of the left boundary and the right boundary of the Y shape through time delay calculation; respectively decomposing respective total field responses into scattered field responses and free field responses, calculating respective infinite domain equivalent node forces and free field node forces according to the scattered field responses and the free field responses, superposing the infinite domain equivalent node forces and the free field node forces to form two groups of final equivalent node force vectors, and respectively applying the two groups of equivalent node force vectors to the left boundary and the right boundary to obtain a final equivalent node force vector. And high-precision input of far-field vibration in layered stepped field SSI analysis is realized.

A method for predicting a focused ultrasound pressure field based on an MRI image may include the steps of: obtaining input data including MRI image data of a skull shape, position data of a FUS transducer, and input free field sound pressure field data, in which the free field sound pressure field means a sound pressure field formed when ultrasound is propagated in a homogeneous medium; inputting the obtained MRI image data of a skull shape, position data of the FUS transducer, and the input free field sound pressure field data into a sound pressure field prediction module; and driving the sound pressure field prediction module to output in real-time the ultrasound pressure field data formed within the skull by the FUS applied by the FUS transducer.

The invention discloses an effective transmission boundary condition-containing two-dimensional structure-foundation seismic response calculation method, which comprises the following steps of: 1, intercepting a complete structure and a foundation part under the structure, and discretizing the structure-foundation into finite element grids, namely a main grid, a free field grid and a transmission layer boundary grid; 2, establishing a kinetic equation of the main grid, the free field grid and the transmission layer grid; and 3, solving the kinetic equations of the main grid, the free field grid and the transmission layer grid by using a Newmark explicit / implicit mixed integral formula to obtain the displacement, the speed and the acceleration of B and I in the structure-foundation model corresponding to each time step. According to the method, the radiation waves of the structure-foundation interaction finite model can be transmitted, the influence of the false reflection waves of the truncation boundary on the calculation of the structure-foundation finite model is eliminated, and the calculation precision of the two-dimensional structure-foundation seismic response is improved.

The application belongs to the technical field of underwater acoustic detection, and discloses an equivalent source method for predicting underwater acoustic cross-medium propagation in a channel space. For an underwater structure in an actual project, a group of equivalent sources are arranged in the interior of the structure to describe the vibration-acoustic response of the structure. The vibration speed of the structure surface is obtained through simulation calculation or arrangement of an acceleration sensor measurement, so that the equivalent source intensity can be determined, and then an underwater structure acoustic radiation model is constructed. The equivalent source is analytically expressed by using a free field space Green function, which does not meet the boundary conditions and the sound velocity gradient characteristics of the ocean channel, and is not applicable to the calculation of channel underwater acoustic and cross-medium propagation. The equivalent source is constructed by using a displacement potential Green function to be unconditionally stable in the channel space, so as to meet the requirements of the channel boundary, the sound velocity gradient and the like, and to establish the underwater acoustic cross-medium propagation. The application arranges a group of equivalent sources in the interior of the structure, uses the vibration speed of the structure surface to solve the equivalent source intensity, describes the vibration-acoustic response of the structure, and establishes a transfer function equivalent source model of vibration-acoustic radiation.

The application belongs to the technical field of acoustic measurement, and discloses a free space sound field measurement method and system, which constructs a free light path sound field measurement system based on the principle of Michelson interferometer; collects a reference image, introduces a sound field to be measured, performs translation and rotation scanning through a computer to control a loudspeaker or a laser beam, and completes interference pattern data collection; pre-processes the collected interference pattern, identifies the edge of the interference fringe by using edge detection technology, and calculates the light phase change amount; sound field reconstruction is performed by using a Radon inverse transform algorithm, sound field integral information carried by the laser beam is converted into the sound pressure value of each point in the real space, and a free field sound pressure distribution map is reconstructed. The application has the advantages of non-destructive and low cost, and significantly improves the sound field measurement accuracy and the integrity and reliability of reconstruction, can effectively capture the nanometer level optical path change caused by the sound field, and ensures the high accuracy of sound field measurement and the accuracy of sound source identification.

According to the method for widening the sound absorption frequency band of the micro-perforated plate sound absorber array under the excitation of the free field oblique incidence plane wave, the coupling sound absorption rule between units in the array is analyzed and fully utilized according to the excitation condition of the free field oblique incidence plane wave; unit structure parameters in the array are subjected to optimization design, the optimal sound absorption performance is achieved, the effective sound absorption frequency band of the MPPA array is greatly widened, and broadband efficient sound absorption of the MPPA array under free field oblique incidence excitation is achieved. The invested cost is low, the sound absorption frequency band broadening effect of the MPPA array is obvious, and therefore the MPPA array has important engineering application value.

The application discloses a method and system for identifying carbonate reservoirs in a well-free work area, comprising the following steps: determining a target interval according to well logging and seismic data of a conjugate basin of a basin where the well-free work area is located; establishing a model for representing the relationship between acoustic velocity and density according to acoustic velocity and density of a well work area in the conjugate basin; obtaining a layer velocity body according to the depth domain seismic velocity of the well-free work area; establishing a pseudo-well density curve and a density body of the well-free work area by using the model for representing the relationship between acoustic velocity and density, and based on this, performing wave impedance inversion calculation of the well-free work area by using the layer velocity body; and identifying favorable carbonate reservoirs in the target interval based on the wave impedance body of the well-free work area.

The invention relates to an underground explosion free field measurement device and method, in particular to an underground explosion free field measurement sensor directional installation device and method, and solves the problems that an existing free field measurement sensor is tedious in installation process, large in work amount and low in cost. The free field measurement sensor directional installation device and the free field measurement sensor directional installation method solve the technical problems that in the prior art, the installation cost is high, the installation angle of a free field measurement sensor is not accurate, underground explosion is affected, and ground medium motion original data measurement is caused. The free field measurement sensor can be quickly and conveniently mounted at the bottom of a test well, and the mounting angle can be accurately adjusted. According to the device, after directional installation of the directional measurement mechanism is completed, a well descending mechanism and a pressing and throwing mechanism are completely removed, only the directional measurement mechanism is reserved in a test well, and the influence of a traditional huge installation frame on a free field measurement result is overcome.

The invention belongs to the technical field of underwater structure non-free field sound calculation, and relates to a rapid engineering calculation method for radiation noise of an underwater vehicle considering the influence of a lake bottom and a lake surface, which comprises the following steps of: intercepting a limited water area containing the underwater vehicle as a finite element calculation area, endowing impedance boundary conditions to the upper and lower surfaces of the limited water area, a perfect matching layer interface is given to the peripheral surface, a load is applied to carry out acoustic-structure interaction calculation, and the vibration velocity of the surface of the radiation surface of the underwater vehicle is obtained; step 2, establishing a boundary element shell calculation model only containing the radiation surface of the underwater vehicle, applying the vibration velocity obtained in the step 1, setting a series of mirror field points based on a mirror source method, and calculating sound pressure of all the mirror field points under a free field condition; based on the positions of the mirror image field points and the acoustic impedance of the lake bottom and the lake surface, the reflection coefficient of each mirror image sound path is calculated, the sound pressure of all the mirror image field points under the free field condition is superposed according to the corresponding reflection coefficients, and the total sound pressure considering the influence of the lake bottom and the lake surface is obtained through synthesis.

An earthquake detection system is disclosed. The earthquake detection system includes a main sensor, a first backup sensor, a second backup sensor and a third backup sensor. The main sensor is disposed on a free field. The first backup sensor is disposed on a structure. The second backup sensor is disposed below a ground surface at a depth of at least 20 meters. The third backup sensor is disposed at a remote end relative to the main sensor, and outputs a remote signal through a network so as to avoid misjudging the occurrence of earthquakes because of unnatural factors, and prevent the vibration caused by human activities from interfering with the detector. The earthquake detection system achieves the effect of verification through a plurality of sensors installed in different positions. Only when all the sensors confirm that there is an earthquake, an earthquake warning will be issued to the protected place.

The invention relates to the technical field of aerodynamic tests, in particular to a shock tube equipment test control system and method, and the system comprises an interaction submodule which comprises a remote controller for controlling a shock tube system; the detection submodule comprises a non-contact acquisition unit, a schlieren unit, an optical acquisition unit and a free field unit, the non-contact acquisition unit is used for acquiring the dynamic pressure change of the surface of the model, and the schlieren unit is used for observing the flow change of the airflow influenced by impact; the optical acquisition unit is used for measuring physical information of a tested model after being impacted by blast waves, and the free field unit is used for measuring pressure distribution conditions of different positions of a free field; and the control execution submodule is in signal connection with the interaction submodule and the detection submodule. The technical problem that complex sequential logic and accurate synchronous control cannot be realized in a shock tube wind tunnel test in the prior art is solved.

The invention relates to the technical field of acoustic engineering, in particular to an equivalent substitution method and system for sound propagation analysis of a volume sound source in a complex sound field environment. The method comprises the following steps: establishing a finite element model of a volume sound source containing complex boundary conditions by utilizing engineering software, carrying out truncation processing on a computational domain, and calculating and obtaining sound pressure and normal vibration velocity on a closed integral surface surrounding the volume sound source; based on the sound pressure and the normal vibration velocity, performing external sound field solution on the closed integral surface by adopting a free field sound radiation integral mode to obtain sound pressure distribution on at least two layers of enveloping surfaces located on the outer side of the volume sound source; arranging a plurality of equivalent point sound sources in the volume sound source, constructing an equivalent source solution equation by taking the sound pressure on at least two layers of envelope surfaces as a matching target, and calculating the source intensity of each equivalent point sound source; and based on the positions of the equivalent point sound sources and the corresponding source intensities of the equivalent point sound sources, accumulative calculation of the volume sound sources in a complex sound field environment is realized by adopting a channel propagation method based on the point sound sources, so that propagation analysis is carried out.

The utility model discloses a microelectronic microphone free field sensitivity testing device, which belongs to the field of microphones and comprises a testing sound source, a reference microphone and a silencing groove. The silencing groove is in a hollow cuboid shape with an opening in the upper portion, a composite sound absorption component is laid on the inner wall of the silencing groove, and the testing sound source is located in the silencing groove and used for sending out pulse signals; a three-dimensional positioning device is arranged above the silencing groove, the three-dimensional positioning device is connected with a mounting seat, four side walls and the bottom of the lower part of the mounting seat are respectively provided with a mounting position for mounting a reference microphone, and the mounting positions can be detachably connected with the reference microphone. And the reference microphone is driven by the three-dimensional positioning device to move to be aligned with the sound center of the test sound source. According to the utility model, rapid and accurate positioning of the test sound source and the reference microphone can be realized, a full-frequency-band sound absorption effect covering high, medium and low frequency bands can be realized, the sound absorption coefficient at the frequency bands above 500Hz is greater than 0.99, and the test precision of the sensitivity of the microelectronic microphone can be improved.

The present invention discloses a miniature speaker test fixture body for equivalent free field testing, including a fixture body, on which a coupling cavity and a pressure relief through hole for connecting the coupling cavity with the outside air are formed. Among them, due to its small volume, the coupling cavity, during the test, the sound waves emitted by the sound-emitting element are concentrated in the coupling cavity and collected by the sound-receiving element located in the coupling cavity, and its sound insulation effect is good, which is equivalent to an anechoic chamber in a free field. At the same time, the pressure relief through hole connects the coupling cavity with the atmosphere, so that the propagation of the sound waves is close to its propagation in the atmosphere, that is, the test environment of the test fixture is equivalent to the test environment of the free field, which is close to the actual use environment of the speaker. The speaker frequency response curve obtained by the test of the miniature speaker test fixture is basically the same as the trend of the speaker frequency response curve measured by the free field, which can be used as an effective basis for R&D personnel to judge the performance of the speaker, and the miniature speaker test fixture has a simple structure and a cost much lower than that of the free field, which is conducive to its promotion and use in small enterprises.

The invention relates to a standard hydrophone free field sensitivity phase response determination method, which comprises the following steps: step 1, determining the amplitude sensitivity of a hydrophone, during measurement, placing a light-reflecting sound-transmitting diaphragm at a point in a far field of an auxiliary emitter, measuring by using a laser interference method to obtain the displacement at the point in a sound field, further obtaining a sound pressure value, and determining the amplitude sensitivity of the hydrophone; the standard hydrophone is placed at the same position in the sound field, the emission state is kept unchanged, the open-circuit voltage response of the standard hydrophone is measured, and the amplitude sensitivity of the standard hydrophone can be measured through a replacement comparison method. According to the method, the phase response can be accurately determined, the influence of many factors on the phase response in a reciprocity method calibration process is solved, and the method has the characteristics of simplicity, convenience and accuracy.