41 results about "Acoustical holography" patented technology

A method of performing near- field acoustic holography comprises the following steps. Establishing (102) acoustic data representing a set of near-field acoustic holography measurements at a first set of positions. Extrapolating (204) acoustic data using a model-based extrapolation to obtain extrapolated acoustic data relating to a plurality of positions outside the aperture. Applying a spatial frequency transform to the padded acoustic data to obtain data in a spatial frequency domain. Propagating (110) the Fourier transformed acoustic data. Applying (112) a regularization in a wavenumber domain. Performing (114) an inverse spatial frequency transform.

The invention provides statistically optimal near-field acoustical holography used for visual recognition of air-conditioner noise sources and an operation method thereof. The operation method comprises the followings: determining the positions, frequency characteristics and distribution ranges of the noise sources, and distance between microphones on microphone arrays, number, sample rates and number of sampling points of microphones; calibrating arrayed microphones; collecting data; recording sound pressure data; processing the sound pressure data; reading the processed data and finally entering noise source recognition procedures. By the invention, complex sound pressure on reconstructive surfaces and vibration velocity of surface particles can be calculated directly via linear superposition of the complex sound pressure on a holographic plane in a spatial domain, thus essentially overcoming window effects and wraparound errors existing in near-field acoustical holography and avoiding the problems brought about by the demand of a large number of microphones by near-field acoustical holography, such as low reconstruction efficiency of sound fields and costly cost of measuring systems, etc. The invention is characterized by small number of demanded microphones, low measuring cost and high reconstruction efficiency of the sound fields.

A method for re-establishing a moving sound source by adopting a moving equivalent source method is characterized in that the method comprises the following steps of measuring Doppler effect-contained sound pressure data in a moving sound source radiation sound field; establishing a transmission relationship between vibration speed and radiation sound pressure under Doppler effect-contained measured sound pressure and sound source static situation by the moving equivalent source; removing the influence of the Doppler effect according to the transmission relationship; and realizing the positioning identification and sound field re-establishment of the moving sound source. The moving sound source applicable to the method can be any shapes including plane, cylindrical surface or spherical surface; and the method is developed on the basis of a near-field acoustical holography reconstruction algorithm based on the equivalent source, has good computation stability, high computation precision and simple execution.

The invention relates to the field of noise, in particular to a sound field separation and reconstruction method applicable to sound field separation and reconstruction of large sound sources. The sound field separation and reconstruction method comprises the following steps of: acquiring sound pressure and normal particle vibration velocity on a measuring surface; performing zero filling extension on the measuring surface positioned between two sound sources; acquiring transfer matrixes between the extended measuring surface and surfaces of the two sound sources, namely sound source faces; building a transitive relation between the sound pressure and the normal particle vibration velocity on the measuring surface; and acquiring the sound pressure and the normal particle vibration velocity of the first sound source face and the sound pressure and the normal particle vibration velocity of the second sound source face. A sound field is separated and reconstructed by using the single-measurement-surface and local near-field acoustical holography method. The sound field separation and reconstruction method has the characteristics of simplicity, short calculation time and high calculation efficiency, and can be widely applied to the measurement of near-field acoustical holography, the measurement of material reflecting coefficients, the separation of scattering sound fields and the like of large-size sound-source sound fields.

The invention provides a piezoelectric underwater sound transducer acoustic radiation mode measurement method and system based on combination near-field acoustical holography. In the method, the combination near-field acoustical holography is utilized to reestablish sound field, sound pressure and radiation surface vibration velocity; on the basis of an acoustic radiation operator matrix obtained based on measurement data and with the sound field radiation theory being combined, the acoustic radiation power of a piezoelectric underwater sound transducer is expressed to be a positive definite quadric form; and positive definite and conjugate performance of the matrix are utilized to obtained an acoustic radiation mode of the structure. The system comprises a glass water tank, an industrial control computer with PXI bus, a transducer excitation module based on the PXI bus, a sound pressure and vibration velocity acquisition module and a three-dimensional motion platform. The method and system in the invention break the limitation that acoustic radiation mode in the current complex underwater structure can only be solved numerically, provide a new idea for research on the piezoelectric underwater sound transducer, and also provide basis for structure optimization of the piezoelectric underwater sound transducer.

The invention belongs to the field of noise like sound field reconstruction and visualization, and particularly relates to a movable noise source recognizing method based on a local near field acoustical holography method. The movable noise source recognizing method includes the steps that sound pressure on a measuring plane H is measured; Doppler effect removal is carried out on the sound pressure obtained through measuring to obtain sound pressure, not containing the Doppler effect, on the measuring plane H; zero padding expansion is performed on the sound pressure on the measuring plane H to obtain sound pressure on a measuring plane H+; a transmission matrix between the sound pressure on the measuring plane H+ and the sound pressure on a reconstruction plane S is calculated; the sound pressure on the reconstruction plane S is solved. Based on the local near field acoustical holography method, the movable noise source recognizing method has the advantages of being simple in calculation, short in calculation time, high in calculation efficiency and the like compared with a traditional method.

The invention provides a method for recognizing three-dimensional coordinates of sound sources via planar arrays. The method comprises the steps of carrying out planar sound field reconstruction at different distances by taking meshed mesh points of a three-dimensional space as reconstruction points via a beam forming method on the basis of a spherical wave sound field model, comparing the output values of beam formers on different reconstruction surfaces along the distance direction (Z direction), and determining the Z-axis coordinate corresponding to the maximum output value as the distance of the sound sources. The method provided by the invention has the advantages of being applied to the two-dimensional arrays, recognizing the three-dimensional coordinates of the sound sources and being directly applied to the existing planar array acoustical holography equipment which is only capable of recognizing the two-dimensional coordinates of the sound sources; and the effectiveness and the reliability of the method are proved by tests.

A system for analyzing noise sources correlates the sound pressure level value at any field point to the acoustic energy directly flowing out of any individual panel of a vibrating structure. This acoustic energy flow or acoustic intensity depicts how sound radiates and in which direction a sound wave propagates in the field. Therefore, the result represents a true contribution of an individual panel to an acoustic field. The acoustic intensity on the surface of a vibrating object is reconstructed by the Helmholtz equation least squares (HELS) based nearfield acoustical holography (NAH). The acoustic intensity is utilized to establish correlations between user-designated panels and the SPL value at any field point. With this information users can rank the order of contributions from individual panels of any vibrating structure to an acoustic field. These order ranking and panel contribution analyses help engineers to come up the best strategy to tackle various noise issues in the most cost-effective manner. The method is applicable to both interior and exterior regions.

A three-dimensional array (10) of microphones (M) is used to determine the three-dimensional sound field above a surface element (ΔS) of a sound emitting surface (S), and the air-particle velocity (un) at the surface element (ΔS) is determined using Near-Field Acoustical Holography (NAH). A volume velocity sound source (11) is used to emit a volume velocity (Qv) in a listening position, and the array (10) of microphones (M) is used to determine the resulting three-dimensional sound field above the surface element (ΔS), and using NAH the resulting sound pressure at the surface element (ΔS) is determined. The acoustic transfer function (H) between the surface element (ΔS) and the listening position is assumed to be reciprocal and is determined as the ratio of the resulting sound pressure at the surface element (ΔS) to the volume velocity (Qv). The sound pressure in the listening position resulting from the surface element (ΔS) is determined as Δp=H.(un. ΔS).

The invention belongs to the technical field of engine pedestal test, and in particular relates to a near field acoustical holography test bracket structure used in engine pedestal test environment. The bracket comprises fixing members and connecting members, the adjacent fixing members are connected by the connecting members, and the fixing members are provided with supported holes. As known fromthe above technical scheme, in the invention, microphones can be put into the supported holes of the fixing members which are connected by the connecting members, and the number and structure of thefixing members and the connecting members can be determined according to the concrete requirement of the test, thus, the invention has simple structure and changeable test structure, therefore, the test effect is better.

The invention provides a simple and effective measuring method of a ground reflection noise source, which has low measuring cost. The measuring method comprises the following steps: A, supporting a finished automobile by hoisting equipment; B, stabilizing the operation working condition of the automobile at the state to be tested; C, horizontally placing a baffle board below an automobile body, wherein a gap between the baffle board and a chassis is same with a gap between a baseboard and the finished automobile when the finished automobile is naturally placed on the ground; translating the baffle board along the length direction of the automobile body; meanwhile, utilizing noise measuring equipment arranged in an automobile chamber to measure noise in the automobile chamber; according to the acoustic pressure level characteristic of attention noise in the automobile when the baffle board is on different positions, determining the main noise resource of noise reflected into the automobile by the baffle board. The measuring method of the ground reflection noise source of the invention can quickly measure the main noise resource of noise reflected into the automobile from ground by simple equipment. Compared with the traditional phonometry or acoustical holography method which is used for determining acoustic source, the measuring method of the invention has simple operation and low measuring cost.

The invention discloses a near-field acoustical holography method based on a combinatorial optimization regularization method. The sound pressure at each point measured on a holographic surface is used, based on a statistical optimal cylinder near-field acoustical holography method, the truncated singular value and standard Tikhonov combinatorial optimization regularization method are used for selected wave number vectors to suppress measurement errors of the wave number vectors caused by the noise and random errors, and that is the combinatorial optimization regularization method; by using the combinatorial optimization regularization method and a GCV method, a superposition coefficient matrix and the sound pressure at each point measured on the holographic surface are obtained, and a sound field on the surface of shell structure equipment can be obtained by expressing the sound pressure at each point on the surface of the shell structure equipment as linear superposition of the conformal measurement surface sound pressure; and effectiveness of the near-field acoustical holography method in shell radiation noise analysis is fully demonstrated, the near-field acoustical holographymethod is suitable for the cylindrical shell structure, a sound field of a cylindrical underwater vehicle is displayed visually, and thus the magnitude and distribution of a radiated sound field can be seen intuitively, so that important theoretical significance and engineering application values are achieved.

The invention discloses a global active noise reduction method for a rotor craft. The method comprises the steps of collection of noise sound pressure signals at rotor measuring points, rotor noise acoustical hologram sound field prediction, rotor noise reverse sound field reconstruction and adaptive sound field adjustment based on optimal phase search. Compared with an existing passive and active noise reduction method, the global active noise reduction method based on acoustical holography and sound field reconstruction does not need to change a rotor wing type or introduce a complex mechanical structure, and only needs to arrange a plurality of measuring devices and secondary sound sources around a machine body, so that the increase of system complexity and cost is avoided, and the method has higher practical value and a better noise reduction effect. In addition, compared with traditional rotor wing noise finite point local noise reduction based on a self-adaptive filtering algorithm, the noise reduction method based on acoustical holography and sound field reconstruction is better in consistency, and can realize real rotor wing global noise reduction.

The invention discloses a transformer vibration noise source positioning system and method, and relates to a vibration noise source positioning method. The transformer vibration noise source positioning system includes a spiral array sensor, a guide rail, a signal processor, a computer and a traction motor, wherein the spiral array sensor utilizes a wave beam shaping algorithm and a near field acoustical holography algorithm to identify the transformer vibration noise source, and at the same time an optical camera shoots the real-time images of a transformer; a classical transfer function database of each voltage class transformer is arranged in a path transfer analysis module, and the path transfer analysis module also includes a crosstalk elimination module, and can solve coupling of thetransfer path; and the final result is stored in a computer in a data form and an ultrasonogram mode. The transformer vibration noise source positioning system and method can be applied to a transformer in each voltage class and each operation condition.

The invention relates to a porous acoustical holography method for sound field identification. The porous acoustical holography method comprises the following steps: 1) designing and processing single microphone arrays, and seeking an optimal arrangement form of the porous microphone arrays in a restricted space through simulating calculation; 2) arranging n single microphone arrays in the actual testing space according to the optimal arrangement form of the porous microphone arrays obtained in the step 1); 3) utilizing the spatial porous microphone arrays to acquire sound pressure signals of a target sound source, selecting a sound field reestablishing surface between the target sound source and the porous microphone arrays, performing porous sound holographic sound field reestablishing on the target sound source, and obtaining the sound field pattern of the target sound source, wherein the main lobe center position in the sound field pattern is the estimated position of the target sound source. The porous acoustical holography method disclosed by the invention can be particularly widely applied to noise control of large construction machinery, and automobiles, trains and airplanes moving rapidly.

The invention provides a near-field acoustical holography reconstruction method based on an equivalent source method. A radiated sound field of a vibration radiator is considered to be formed by a superposition of sound fields generated by a series of equivalent sources arranged in the radiator. Source intensity of the equivalent sources can be obtained by normal velocity matching of the radiator surface. Thus, sound radiation is calculated. The near-field acoustical holography reconstruction method based on the equivalent source method is suitable for near-field acoustical holography of sound sources of arbitrary shapes and is adopted to raise computational efficiency and computational accuracy.

The invention discloses a method for detecting non-stationary acoustic sources based on a near-field acoustical holography technology. The method includes the following steps that (1), according to the acoustic emission phenomenon of the non-stationary acoustic sources, a cylindrical surface-spherical surface non-conformal surface acoustical holography experimental model is established according to the near-field acoustical holography technology; (2), the number of detection points and the number of reconstructed spherical surface nodes are set for single acoustic sources on the experimental model, simulation experiment analyzing is performed, and parameters are selected; (3), according to the parameter selection result of single acoustic source simulation, double acoustic sources are reconstructed, and the effectiveness of the method is verified; (4), through analyzing experimental data, the selection rule of the distances from a particular solution point source to the nodes on a reconstructed spherical surface and main parameters affecting reconstruction precision are fictional; (5), according to optimal simulation experiment parameters, an acoustical holography experiment system is designed. The non-stationary acoustic source is positioned through the near-field acoustic holography technology, the position and the characteristics of the non-stationary acoustic source can be accurately measured, and therefore convenience is provided for effective control over noise.

The invention provides a near-field acoustical holography reconstruction method based on the Fourier transformation and source strength simulation technology. The near-field acoustical holography reconstruction method based on the Fourier transformation and source strength simulation technology comprises the steps that continuous simple sources are arranged on a rectangular virtual source surface, and a source strength function is a three-dimensional free space Green function; double Fourier series expansion is carried out on an unknown source strength density function, and a sound pressure expression is deduced; expressions of the sound pressure on measuring points on a holographic surface are deduced through quick Fourier transformation and inverse transformation calculation, and a non-homogeneous linear equation set which uses a Fourier series expansion coefficient as an unknown term and the sound pressure as a constant term is formed through arrangement; the Fourier series expansion coefficient is obtained by solving the non-homogeneous linear equation set through a generalized inverse matrix, the Fourier series expansion coefficient is substituted into a reconstruction formula in a back substitution mode, the expression of the sound pressure on any field point in a radiation field is obtained, and reconstruction and prediction of the whole space sound field are achieved. According to the near-field acoustical holography reconstruction method based on the Fourier transformation and source strength simulation technology, implementation is easy, the calculating speed is high, limitation cannot be caused by the limited hole diameter, and the near-field acoustical holography reconstruction method is applicable to sound sources with any shapes.

The invention relates to a near-field acoustical holography testing system in a noise environment and application thereof. The system comprises a rigid acoustical shielding cover, a microphone array,a base, a data collection instrument and an upper computer, wherein the microphone array comprises a plurality of sensors; the rigid acoustical shielding cover comprises a bottom surface and four sides; a plurality of holes are discretely formed in the bottom surface; the number of the holes is consistent with that of the sensors; each hole is in one-to-one correspondence to each sensor; the sensors are embedded in corresponding holes in the bottom surface of the rigid acoustical shielding cover and are in flush with the inner surface of the bottom surface; the microphone array, the data collection instrument and the upper computer are successively connected with each other; and the rigid acoustical shielding cover and the microphone array are fixed and supported by the base. Compared withthe prior art, the near-field acoustical holography testing system has the advantage that the noise source surface vibration velocity can be more conveniently rebuilt in the noise environment.

The invention discloses a near-field acoustical holography measurement method in a limited space based on an equivalent source method, and the method comprises the steps: 1, building a near-field acoustical holography measurement model in the limited space, and obtaining the sound pressure and vibration velocity of a sound source in a measurement surface in the limited space: 2, configuring the number of virtual sources and the positions of the virtual sources; 3, establishing a near-field acoustical holography measurement model of the monopole point sources in the limited space, and obtaining the sound pressure vibration velocity of each monopole point source in a measurement surface in the limited space; 4; solving a Green function in the limited space; 5, solving sound pressure and vibration velocity information on a sound source measurement surface of the known structure through the transfer relation solved in the previous step to obtain the source intensity of the equivalent source in the structure; 6, calculating information such as sound pressure of the structure in the free field through the solved source intensity of the equivalent source. According to the method, a limited space test environment is considered, a traditional equivalent source method is improved, and the influence of an interface in a limited space on sound pressure and a vibration velocity field of a source surface is considered, so that the reconstruction precision is improved.

The invention discloses a cylindrical shell sound field step-by-step combination reconstruction method based on plane testing. The method comprises the following steps: establishing an optimal intermediate conversion surface conformal with a to-be-measured cylindrical shell sound source; on the basis of statistics of an optimal near-field acoustic holography theory, reasonably selecting a conformal conversion surface with the minimum total reconstruction error of primary reconstruction of a plane wave function; converting plane test sound pressure data into a cylindrical conformal conversion surface by utilizing statistical optimal plane near-field acoustic holography; and calculating the sound pressure of the cylindrical sound source by utilizing the statistical optimal cylindrical surface near-field acoustical holography and the sound pressure of the conversion surface. The characteristics that a plane wave function has a relatively simple requirement on a holographic surface test and a cylindrical wave function has higher reconstruction precision on a sound field of a cylindrical shell structure are combined, the limitation that data acquisition is difficult due to the fact thata holographic surface and a sound source surface are required to be conformal in a traditional method is broken through, high-precision reconstruction of the sound field of the cylindrical shell structure is achieved, the reconstruction precision of the cylindrical shell structure is improved, and the problem that the holographic surface conformal with the shell structure is difficult to arrangein actual testing is solved.

The invention discloses a sound field reconstruction system and method based on sound pressure and particle vibration velocity, and the system comprises a multi-sensor scanning module which is used for carrying out the scanning through an array composed of sound vector sensors, and obtaining the sound pressure and particle vibration velocity data of a measurement surface; a multi-channel real-time data acquisition module, used for performing multi-channel real-time acquisition on sound pressure and particle vibration velocity data based on labview; a filtering module, used for filtering data points of which the amplitudes are smaller than a preset value on the measuring surface by using the amplitude filtering coefficient of the sound field measuring surface; and a sound field reconstruction module, used for performing sound field reconstruction by using a near-field acoustical holography method based on an equivalent source method, including sound field reconstruction of sound pressure, sound field reconstruction of mass point vibration velocity and sound field reconstruction of a sound intensity field. The mass point vibration velocity is introduced on the basis of the original equivalent source method near-field acoustical holography based on sound pressure to reconstruct the sound field, so that the sound field reconstruction precision and the sound source positioning precision are effectively improved.

The invention belongs to the technical field of mechanical structure sound radiation signal processing, and discloses a sound field reconstruction method based on planar array scanning, which comprises the following steps of: performing stepping scanning in a spatial two-dimensional direction by using a small planar array to obtain sound pressure data of scanning planar arrays at different positions; overlapping measurement is carried out in adjacent areas of the scanning area arrays, and phase deviation caused by non-simultaneous measurement between sound pressure values of the adjacent scanning area arrays is calculated; and by averaging the sound pressure amplitudes at the overlapping positions, the complex sound pressure data on all the scanning area arrays are combined to the synthetic measurement surface. And the sound pressure value of the synthetic measurement surface is combined with a near-field acoustical holography method based on Fourier transform to realize reconstruction of a space sound field. According to the method, the sound field measurement and reconstruction in a larger range are completed by using fewer measuring points, the number of required acoustic sensors is small, the measurement cost is low, the sound field reconstruction precision is high, the calculation speed is high, the window effect problem in a traditional sound field reconstruction method is effectively avoided, and the size modulation of a synthetic measurement surface is realized.

The invention discloses a three-dimensional distribution visualization method for sound quality objective parameters based on a Patch near-field acoustical holography technology. According to the method, frequent scanning measurement is carried out on the surface of a large-scale complex sound source by means of a small microphone array in a sound field formed by large-scale structured sound source radiation, wherein incoming waves and outgoing waves exist in the sound field; the distribution information of acoustic quantities and sound quality objective parameters in the whole space sound field can be obtained through a Patch near-field acoustical holography and sound quality coupling matrix calculation model, and therefore the three-dimensional distribution visualization for the acoustics physical quantities and the sound quality objective parameters can be achieved.

The present invention provides a reflective acoustic holographic imaging method based on a metasurface, including a reflective acoustic holographic imaging device. The method includes: acquiring the working frequency of the reflective acoustic holographic imaging device, determining the initial sound wave at the working frequency; Vertically incident into the reflective acoustic holographic imaging device to obtain the reflected sound wave; input the reflected sound wave to the reflected sound wave correction model to obtain the corrected sound wave; reconstruct the target image on the imaging surface of the reflective acoustic holographic imaging device according to the corrected sound wave; the present invention The beneficial effect is: it is used to solve the problem that the traditional use of acoustic metasurfaces to directly generate a holographic sound field by designing a unit structure will cause deviations in holographic imaging due to acoustic wave interference when applied in special scenes.

The invention discloses a variable norm equivalent source near-field acoustical holography algorithm with sound source sparseness adaptability. The algorithm comprises the following steps: arranging a holographic surface in a sound source near-field radiation area, and measuring to obtain sound pressure PH on the holographic surface; arranging an equivalent source surface on one side, away from the holographic surface, of a target reconstruction surface; establishing a relationship between the sound pressure and an equivalent source by using a sound pressure transfer matrix between the equivalent source and the holographic surface; and solving the source intensity of the equivalent source by adopting an iterative regularization algorithm with a self-adaptive norm constraint penalty term, and calculating by using the obtained source intensity and a transfer matrix between the equivalent source and the target reconstruction surface to obtain sound field data on the target reconstruction surface. According to the method, the p value in an lp norm penalty term in the regularization solving process is adaptively changed, so that the sparseness of the source intensity of the equivalent source obtained through solving is more consistent with the actual sparseness of the sound source, and accurate solving can be achieved for a space sparse sound source, a space continuous sound source or a sound source with the source intensity sparseness between sufficient sparseness and continuity.

The three-dimensional positioning method for the gas leakage position comprises the following steps: establishing a sound field model based on a Kirchhoff diffraction far-field acoustical holography theory; acquiring leakage source sound field information on the measurement plane; processing the obtained sound field information to obtain acoustical holography data of the leakage source sound field; and determining the three-dimensional position information of the leakage source by using the sound field model and the acoustical holography data. According to the three-dimensional positioning method for the gas leakage position, more accurate sound field information can be obtained, and then depth information can be introduced to realize three-dimensional detection effect display of a leakage source; by constructing a far-field acoustical holography model based on the Kirchhoff diffraction theory, sound field positioning of a large-distance leakage source can be realized; and the virtual phased array technology is utilized, the system cost and complexity are reduced in gas leakage detection and positioning, the leakage source detection precision and positioning precision are improved, and the method has huge practical value and industrial application potential in the aspect of accurate positioning of the gas leakage position.

The invention discloses a system for detecting a non-stationary acoustic source based on a near-field acoustical holography technology. The system is characterized by sequentially comprising an acoustic emission sensor array, a broadband acoustic emission pre-amplifier, an AD converter, a DSP, an upper computer and a graphic displayer. Acoustic source recognition algorithm analysis and processing software is operated in the upper computer. The non-stationary acoustic source is positioned through the near-field acoustical holography technology, the position and the characteristics of the non-stationary acoustic source can be accurately measured, and therefore convenience is provided for effective control over noise.