CN112468931B - Sound field reconstruction optimization method and system based on spherical harmonic selection - Google Patents
Sound field reconstruction optimization method and system based on spherical harmonic selection Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R1/00—Details of transducers, loudspeakers or microphones
- H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
- H04R1/32—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only
- H04R1/40—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by combining a number of identical transducers
- H04R1/403—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by combining a number of identical transducers loud-speakers
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R5/00—Stereophonic arrangements
- H04R5/02—Spatial or constructional arrangements of loudspeakers
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R2430/00—Signal processing covered by H04R, not provided for in its groups
- H04R2430/20—Processing of the output signals of the acoustic transducers of an array for obtaining a desired directivity characteristic
Abstract
The invention discloses a sound field reconstruction optimization method and system based on spherical harmonic selection, wherein the method is a method capable of optimizing sound field reconstruction errors on the premise of not changing loudspeaker arrangement. When the sound field reconstruction error is optimized, a user provides spherical harmonic coefficients corresponding to a target sound field to be reconstructed, and then partial target spherical harmonic coefficients are optimized and selected for preferential reconstruction, so that the reconstruction error of the sound field (for example, sound waves in a certain direction) is reduced. The method has the performance advantage that the target reconstruction sound field and the reconstruction global sound field (sound pressure) error are considered at the same time, and the error of sound field reconstruction by utilizing spherical harmonic expression can be further reduced. The expression capability of the current reconstruction loudspeaker set to the sound field is considered during sound field reconstruction, and the sound field reconstruction performance of the current loudspeaker set is utilized to the maximum extent.
Description
Technical Field
The invention relates to the technical field of digital audio signal processing, in particular to a sound field reconstruction optimization method and system based on spherical harmonic selection.
Background
The development of information technology has led to a variety of new media, and network media are on the rise worldwide. The network media provides information and entertainment contents to users through channels such as internet, wireless communication network, cable television network and the like and digital terminals such as computers, mobile phones, smart televisions and the like by using digital technology, network technology and mobile communication technology. Although the visual elements in the existing video system have been expanded to three-dimensional space, the currently mainstream video sound system is mainly a traditional 2.1 stereo or 5.1/7.1 surround sound system with a single horizontal layer. According to the definition of three-dimensional audio proposed in the MPEG conference in 2012, the three-dimensional audio system can reconstruct three-dimensional surround sound images with three degrees of freedom including horizontal direction, vertical direction and distance, and the sound images can be located at any spatial position in a three-dimensional space, so as to realize the realistic sound effect of surrounding sense of the full three-dimensional space.
Sound field reconstruction techniques are important techniques for realizing three-dimensional audio. The sound field refers to a region in which sound waves exist in a medium, and physical quantities describing the sound field may be sound pressure, particle vibration velocity, displacement, medium density, or the like. Sound field reconstruction techniques achieve the reproduction of the listening experience by reconstructing the original sound field in a new environment. Many internationally studied sound field reconstruction by scholars and scientific research institutes have been proposed, and many methods for sound field reconstruction have been proposed, among which the most representative hoa (high Orders of ambisonics) technology. The technology decomposes a sound field into a group of linear combinations of spherical harmonic functions which are orthogonal with each other, and solves a driving signal of a loudspeaker according to the spherical harmonic coefficient (the coefficient of each spherical harmonic function in the linear combination) of a target sound field, thereby realizing approximate reconstruction of the sound field. However, the HOA adopts a least square method to solve the spherical harmonic coefficient, and the global sound field error is not optimally solved, so that the further reduction of the sound field reconstruction error is limited.
Therefore, the method in the prior art has the technical problem of large sound field reconstruction errors.
Disclosure of Invention
The invention provides a sound field reconstruction optimization method and system based on spherical harmonic selection, which are used for solving or at least partially solving the technical problem of larger sound field reconstruction errors in the method in the prior art.
In order to solve the above technical problem, a first aspect of the present invention provides a sound field reconstruction optimization method based on spherical harmonic selection, including:
s1: acquiring sound field data acquired by a reconstructed loudspeaker group at a target position under the excitation of a unit signal according to the arrangement of the reconstructed loudspeaker group in the current environment, and acquiring unit signal spherical harmonic coefficients of the loudspeaker group based on the acquired sound field data;
s2: acquiring sound field data to be reconstructed, taking the sound field data to be reconstructed as target sound field data, and performing spherical harmonic decomposition on the target sound field data to acquire corresponding spherical harmonic coefficients;
s3: reconstructing a loudspeaker driving signal of a target sound field according to the obtained unit signal spherical harmonic coefficient of the loudspeaker group and a target spherical harmonic coefficient selected from the spherical harmonic coefficients corresponding to the target sound field data, and calculating a global error between the reconstructed sound field and the target sound field based on the reconstructed loudspeaker driving signal of the target sound field;
s4: and selecting a target reconstruction scheme according to the global error between the reconstructed sound field and the target sound field.
In one embodiment, step S1 includes:
collecting a certain number of sound pressures p in a target range by using a microphone array with Q microphones, and acquiring corresponding spherical harmonic coefficients according to the following formula
Wherein n is the order of the spherical harmonic coefficient, m is the subscript of m coefficients under the spherical harmonic coefficient of n order, x is the sound field radius corresponding to the target range,
for the position acquired by the microphone array at frequency f
Acoustic pressure of (a) < omega >qWeights corresponding to spherical integrals, jn(. is) a spherical Bessel function of order n, c is the speed of sound, Ynm(. cndot.) is a spherical harmonic, conjugate,
Pnm(. DEG) is Legendre function, and theta, phi is corresponding position
I is an imaginary number unit; converting the spherical harmonic coefficients obtained from the loudspeaker signals into a matrix form:
wherein the content of the first and second substances,
corresponding to the spherical harmonic coefficients collected by the loudspeakers numbered 1 to L
In one embodiment, S2 includes:
according to the sound pressure p of a target sound field at a specific position, acquiring a corresponding spherical harmonic coefficient according to a formula:
n is the order of the spherical harmonic coefficient, m is m coefficient subscripts under the spherical harmonic coefficient of the n order, x is the radius of the sound field corresponding to the target range,
for the position acquired by the microphone array at frequency f
Acoustic pressure of (a) < omega >qWeights corresponding to spherical integrals, jn(. cndot.) is a spherical Bessel function of order n, c is the speed of sound,Ynm(. cndot.) is the spherical harmonic, conjugate:
forming spherical harmonic coefficients of a target sound field into a vector:
β＝{β0,0(f),β1,-1(f),...,βn,n(f)},
wherein, betan,mCorresponding to the collected spherical harmonic coefficient Cnm(f)。
In one embodiment, S3 specifically includes:
step S3.1: calculating a speaker driving signal for reconstructing a target sound field based on a unit signal spherical harmonic coefficient of the speaker group and a target spherical harmonic coefficient selected from spherical harmonic coefficients corresponding to target sound field data:
wherein S isLRepresenting loudspeaker drive signals for reconstructing a target sound field, HKRepresents a matrix formed by target spherical harmonic coefficients selected from spherical harmonic coefficients corresponding to target sound field data, betaKRepresenting a vector of selected k target coefficients,
is the pseudo-inverse of the matrix, and T is the vector transposition;
step S3.2: calculating spherical harmonic coefficients of the reconstructed sound field according to the loudspeaker driving signals of the reconstructed target sound field:
β′T＝HL×SL
wherein HLA matrix formed by spherical harmonic coefficients of unit signals is expressed;
step S3.3: calculating the global error between the reconstructed sound field and the target sound field according to the spherical harmonic coefficient of the reconstructed sound field,
wherein R is the radius of the target reconstruction sound fieldThe error function will integrate over the whole sphere of the target area,
is the sound pressure of the reconstructed sound field, and p (-) is the sound pressure of the target sound field, | | | is a1 norm, the spherical harmonic function is in place
The corresponding sound pressure can be calculated by the following formula:
x is
N is the order of the spherical harmonic coefficient.
In one embodiment, in step S3, the different reconstruction schemes are corresponding to each other based on the number and combination of the selected target spherical harmonic coefficients, and each reconstruction scheme corresponds to one reconstruction error, where the reconstruction error is a global error between the reconstructed sound field and the target sound field.
In one embodiment, step S4 specifically includes:
according to the reconstruction errors corresponding to all the reconstruction schemes obtained in step S3, the scheme with the lowest global error is selected as the optimal reconstruction scheme:
wherein phi isKAll the spherical harmonic coefficients of the reconstructed sound field calculated for preferentially reconstructing K spherical harmonic coefficients, N being the highest spherical harmonic order to be reconstructed, and beta' being the number phiKIn any scheme selected from (1), epsilon (beta ') is the sound field reconstruction error corresponding to the selected reconstruction scheme beta ', and the final optimal reconstruction scheme is beta 'minThe corresponding loudspeaker drive signal.
Based on the same inventive concept, the second aspect of the present invention provides a sound field reconstruction optimization system based on spherical harmonic selection, comprising:
the device comprises a reconstruction loudspeaker group data acquisition module, a reconstruction loudspeaker group data acquisition module and a reconstruction loudspeaker group data acquisition module, wherein the reconstruction loudspeaker group data acquisition module is used for acquiring sound field data acquired by a target position of a reconstruction loudspeaker group under the excitation of a unit signal according to the arrangement of the reconstruction loudspeaker group under the current environment, and acquiring the unit signal spherical harmonic coefficient of the loudspeaker group based on the acquired sound field data;
the target sound field data acquisition module is used for acquiring sound field data to be reconstructed, taking the sound field data to be reconstructed as target sound field data, and performing spherical harmonic decomposition on the target sound field data to acquire corresponding spherical harmonic coefficients;
the sound field reconstruction error calculation module is used for reconstructing a loudspeaker driving signal of a target sound field according to the acquired unit signal spherical harmonic coefficient of the loudspeaker group and a target spherical harmonic coefficient selected from the spherical harmonic coefficients corresponding to the target sound field data, and calculating a global error between the reconstructed sound field and the target sound field based on the loudspeaker driving signal of the reconstructed target sound field;
and the optimal sound field reconstruction scheme selection module is used for selecting a target reconstruction scheme according to the global error between the reconstructed sound field and the target sound field.
One or more technical solutions in the embodiments of the present application have at least one or more of the following technical effects:
the method provided by the invention can optimize the sound field reconstruction error on the premise of not changing the arrangement of the loudspeakers, when the sound field reconstruction error is optimized, the loudspeaker driving signal of the target sound field can be reconstructed according to the acquired unit signal spherical harmonic coefficient of the loudspeaker group and the target spherical harmonic coefficient selected from the spherical harmonic coefficients corresponding to the target sound field data, namely, the spherical harmonic coefficient corresponding to the target sound field needing to be reconstructed can be provided by a user, and then, the preferential reconstruction is carried out by optimizing and selecting part of the target spherical harmonic coefficients, so that the reconstruction error of the sound field (such as sound wave in a certain direction) when the sound field is reconstructed is reduced. The method has the performance advantage that the target reconstruction sound field and the reconstruction global sound field (sound pressure) error are considered at the same time, and the error of sound field reconstruction by utilizing spherical harmonic expression can be further reduced.
Furthermore, the expression capability of the current reconstructed loudspeaker group to the sound field is considered during sound field reconstruction, and the sound field reconstruction performance of the current loudspeaker group is utilized to the maximum extent.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a flowchart of a sound field reconstruction optimization method based on spherical harmonic selection according to the present invention.
Detailed Description
In order to solve the technical problems of the existing sound field reconstruction method, the invention provides a method for optimizing the sound field reconstruction error on the premise of not changing the arrangement of speakers. The technology carries out preferential reconstruction by optimally selecting partial target spherical harmonic coefficients, thereby reducing the reconstruction error when reconstructing a specific sound field (such as sound waves in a certain direction).
The main inventive concept of the present invention is as follows:
a method is proposed that allows to optimize the sound field reconstruction errors without changing the loudspeaker arrangement. When the sound field reconstruction error is optimized, a user provides spherical harmonic coefficients corresponding to a target sound field to be reconstructed, and then partial target spherical harmonic coefficients are optimized and selected for preferential reconstruction, so that the reconstruction error of the sound field (for example, sound waves in a certain direction) is reduced. The method has the advantages that the target reconstruction sound field and the reconstruction global sound field (sound pressure) error are considered at the same time, and the error of sound field reconstruction by utilizing spherical harmonic expression can be further reduced. The expression capability of the current reconstruction loudspeaker set to the sound field is considered during sound field reconstruction, and the sound field reconstruction performance of the current loudspeaker set is utilized to the maximum extent.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In specific implementation, the technical scheme provided by the invention can be implemented by a person skilled in the art by adopting a computer software technology to realize an automatic operation process. The technical scheme of the invention is explained in detail in the following by combining the drawings and the embodiment.
Example one
Referring to fig. 1, an embodiment of the present invention provides a sound field reconstruction optimization method based on spherical harmonic selection, including:
s1: acquiring sound field data acquired by a reconstructed loudspeaker group at a target position under the excitation of a unit signal according to the arrangement of the reconstructed loudspeaker group in the current environment, and acquiring unit signal spherical harmonic coefficients of the loudspeaker group based on the acquired sound field data;
s2: acquiring sound field data to be reconstructed, taking the sound field data to be reconstructed as target sound field data, and performing spherical harmonic decomposition on the target sound field data to acquire corresponding spherical harmonic coefficients;
s3: reconstructing a loudspeaker driving signal of a target sound field according to the obtained unit signal spherical harmonic coefficient of the loudspeaker group and a target spherical harmonic coefficient selected from the spherical harmonic coefficients corresponding to the target sound field data, and calculating a global error between the reconstructed sound field and the target sound field based on the reconstructed loudspeaker driving signal of the target sound field;
s4: and selecting a target reconstruction scheme according to the global error between the reconstructed sound field and the target sound field.
Specifically, step S1 is to mainly acquire the unit signal spherical harmonic coefficient of the speaker group. In particular applications, the data may be acquired at multiple target reconstruction locations. The unit signal spherical harmonic coefficient of the loudspeaker set can be used for calculating a sound field generated under the drive of any signal.
Step S2 is configured to preprocess the target sound field data, and convert the discrete sound pressure value obtained after the time-frequency transform into a spherical harmonic coefficient form required by the calculation.
The sound field data acquired at the target position in step S1 is the result of the signal reproduced by the acquired speaker being affected by the effect such as spatial environment reflection, and is expressed in the form of the sound field acquired at the target position by the speaker excited by the unit signal.
The target sound field data in step S2 is for acquiring sound field data to be reconstructed, and can be acquired in any environment at any position (without defining a sound source and an acquisition position). Which will eventually be reconstructed by the loudspeaker array at the target reconstruction location. That is, the "sound field data collected at the target position" refers to sound field data collected by the speaker array (sound source) at the target position (collection position). "target sound field data" refers to sound field data to be reconstructed at a target position, and can be collected at an arbitrary position in an arbitrary environment (without defining a sound source and a collection position).
The step S3 selects the target spherical harmonic coefficients from the spherical harmonic coefficients corresponding to the target sound field data according to actual conditions, for example, randomly selecting K target spherical harmonic coefficients from N target spherical harmonic coefficients. There are various options according to the number of choices and the combination. Different target spherical harmonic coefficients correspond to one reconstruction scheme, and one reconstruction scheme corresponds to one global error.
Step S4 is to select a target reconstruction scheme, i.e., a scheme with the minimum global error, from the multiple reconstruction schemes according to the global errors between the reconstructed sound field and the target sound field.
In one embodiment, step S1 includes:
collecting a certain number of sound pressures p in a target range by using a microphone array with Q microphones, and acquiring corresponding spherical harmonic coefficients according to the following formula
Wherein n is the order of the spherical harmonic coefficient, m is the subscript of m coefficients under the spherical harmonic coefficient of n order, x is the sound field radius corresponding to the target range,
for the position acquired by the microphone array at frequency f
Acoustic pressure of (a) < omega >qWeights corresponding to spherical integrals, jn(. cndot.) is a spherical Bessel function of order n, c is the speed of sound, Ynm(. cndot.) is a spherical harmonic, conjugate,
Pnm(. DEG) is Legendre function, and theta, phi is corresponding position
I is an imaginary number unit; converting the spherical harmonic coefficients obtained from the loudspeaker signals into a matrix form:
wherein, the first and the second end of the pipe are connected with each other,
corresponding to the spherical harmonic coefficients collected by the loudspeakers numbered 1 to L
Specifically, the purpose of step S1 is to acquire the sound field (data) formed at the target position by the loudspeaker group driven by the unit signal under the current environment and arrangement after the emitted sound wave is reflected, diffracted, etc. by the environment. The spherical harmonic coefficient of the unit signal of the loudspeaker set can be calculated according to the formula and then converted into a matrix form.
The calculation of the spherical harmonic coefficient generated at the target position with the loudspeaker-unit driving signal is only for illustrating the specific implementation flow of the present invention, and is not limited to the present invention.
In one embodiment, S2 includes:
according to the sound pressure p of a target sound field at a specific position, acquiring a corresponding spherical harmonic coefficient according to a formula:
n is the order of the spherical harmonic coefficient, m is m coefficient subscripts under the spherical harmonic coefficient of the n order, x is the radius of the sound field corresponding to the target range,
for the position acquired by the microphone array at frequency f
Acoustic pressure of (f), ωqWeights corresponding to spherical integrals, jn(. is) a spherical Bessel function of order n, c is the speed of sound, Ynm(. cndot.) is the spherical harmonic, conjugate:
forming spherical harmonic coefficients of a target sound field into a vector:
β＝{β0,0(f),β1,-1(f),...,βn,n(f)},
wherein beta isn,mCorresponding to the collected spherical harmonic coefficient Cnm(f)。
Specifically, spherical harmonic decomposition is performed on the target reconstructed sound field, and corresponding spherical harmonic coefficients can be obtained. In a specific implementation, if the target sound field gives spherical harmonic coefficients, the spherical harmonic coefficients can be sequentially cut out as reconstruction targets according to the number of the reconstruction loudspeakers.
In one embodiment, S3 specifically includes:
step S3.1: calculating a speaker driving signal for reconstructing a target sound field based on a unit signal spherical harmonic coefficient of the speaker group and a target spherical harmonic coefficient selected from spherical harmonic coefficients corresponding to target sound field data:
wherein S isLRepresenting loudspeaker drive signals for reconstructing a target sound field, HKRepresents a matrix formed by target spherical harmonic coefficients selected from spherical harmonic coefficients corresponding to target sound field data, betaKRepresenting a vector of selected k target coefficients,
is the pseudo-inverse of the matrix, and T is the vector transposition;
step S3.2: calculating spherical harmonic coefficients of the reconstructed sound field according to the loudspeaker driving signals of the reconstructed target sound field:
β′T＝HL×SL
wherein HLA matrix formed by spherical harmonic coefficients of unit signals is expressed;
step S3.3: calculating the global error between the reconstructed sound field and the target sound field according to the spherical harmonic coefficient of the reconstructed sound field,
wherein R is the radius of the target reconstruction sound field, the error function is integrated in the sphere of the whole target area,
is the sound pressure of the reconstructed sound field, and p (-) is the sound pressure of the target sound field, | | | is a1 norm, the spherical harmonic function is in place
The corresponding sound pressure can be calculated by the following formula:
x is
N is the order of the spherical harmonic coefficient.
In one embodiment, in step S3, the target spherical harmonic coefficients are selected according to the number and combination form thereof, and each reconstruction scheme corresponds to a reconstruction error, which is a global error between the reconstructed sound field and the target sound field.
Specifically, k (1 ≦ k ≦ n) are selected from all the target spherical harmonic coefficients (n) according to a combinatorial enumeration. For example, a scheme for selecting any k spherical harmonic coefficients from 4 spherical harmonic coefficients is as follows: {1}, {2}, {3}, {4}, {1,2}, {1,3}, {1,4}, {2,3}, {2,4}, {3,4}, {1,2,3}, {1,2,4}, {2,3,4}, {1,2,3,4}, and 2 in total4-1 protocol.
And calculating a loudspeaker driving signal for reconstructing a target sound field according to the unit signal spherical harmonic coefficient of the loudspeaker group and the partially selected target spherical harmonic coefficient. In a specific implementation, a typical selection method is combinatorial selection: for a target sound field containing n spherical harmonic coefficients, k coefficients are selected as a priority reconstruction target, and the total number is 2n-1 selection mode. According to the selected k coefficients (subscripts respectively correspond to k)1To kk) Selecting HLThe corresponding k rows:
selecting corresponding k target coefficients from the beta:
calculating corresponding loudspeaker driving signal S according to formulaL：
Wherein
T is the vector transpose, which is the pseudo-inverse of the matrix.
In one embodiment, step S4 specifically includes:
according to the reconstruction errors corresponding to all the reconstruction schemes obtained in step S3, the scheme with the lowest global error is selected as the optimal reconstruction scheme:
wherein phiKAll the spherical harmonic coefficients of the reconstructed sound field calculated for preferentially reconstructing K spherical harmonic coefficients, N being the highest spherical harmonic order to be reconstructed, and beta' being the number phiKIn any scheme selected from (1), epsilon (beta ') is a sound field reconstruction error corresponding to the selected reconstruction scheme beta ', and the final optimal reconstruction scheme is beta 'minThe corresponding loudspeaker drive signal.
Specifically, the reconstruction errors obtained by the plurality of selection schemes can be calculated through the aforementioned steps S1 to S3, and the errors are recorded until all the selection schemes are completed. Step S4 is to select the scheme with the lowest global error as the optimal reconstruction scheme from the obtained reconstruction errors corresponding to all the selection schemes.
In a specific implementation process, the sound field reconstruction optimization method based on spherical harmonic selection provided by the invention can be subdivided into the following steps:
step A1: and acquiring unit signal spherical harmonic coefficients of the loudspeaker group.
Step A2: and performing spherical harmonic decomposition on the target reconstruction sound field to obtain corresponding spherical harmonic coefficients.
Step A3: according to the mode of combination selection, parts are selected from all spherical harmonic coefficients of the target sound field to be preferentially reconstructed.
Step A4: and calculating a loudspeaker driving signal for reconstructing a target sound field according to the unit signal spherical harmonic coefficient of the loudspeaker group and the partially selected target spherical harmonic coefficient.
Step A5: and calculating spherical harmonic coefficients of the reconstructed sound field according to the driving signals of the reconstructed loudspeaker group.
Step A6: and calculating the global error with the target sound field according to the spherical harmonic coefficient of the reconstructed sound field.
Step A7: repeat steps A2 through A6 until all options are complete.
Step A8: and selecting the scheme with the lowest global error as the optimal reconstruction scheme.
The step A1 corresponds to S1, the step A2 corresponds to S2, the steps A3 to A7 correspond to S3, and the step A8 corresponds to S4.
Compared with the existing HOA-based sound field reconstruction method, the method has the following positive effects and advantages:
1. meanwhile, target reconstruction sound field errors and reconstruction global sound field (sound pressure) errors are considered, and the errors of sound field reconstruction by utilizing spherical harmonic expression can be further reduced.
2. The expression capability of the current reconstruction loudspeaker set to the sound field is considered during sound field reconstruction, and the sound field reconstruction performance of the current loudspeaker set is utilized to the maximum extent.
Example two
Based on the same inventive concept, the present embodiment provides a sound field reconstruction optimization system based on spherical harmonic selection, including:
the device comprises a reconstruction loudspeaker group data acquisition module, a reconstruction loudspeaker group data acquisition module and a reconstruction loudspeaker group data acquisition module, wherein the reconstruction loudspeaker group data acquisition module is used for acquiring sound field data acquired by a target position of a reconstruction loudspeaker group under the excitation of a unit signal according to the arrangement of the reconstruction loudspeaker group under the current environment, and acquiring the unit signal spherical harmonic coefficient of the loudspeaker group based on the acquired sound field data;
the target sound field data acquisition module is used for acquiring sound field data to be reconstructed, taking the sound field data to be reconstructed as target sound field data, and performing spherical harmonic decomposition on the target sound field data to acquire corresponding spherical harmonic coefficients;
the sound field reconstruction error calculation module is used for reconstructing a loudspeaker driving signal of a target sound field according to the acquired unit signal spherical harmonic coefficient of the loudspeaker group and a target spherical harmonic coefficient selected from the spherical harmonic coefficients corresponding to the target sound field data, and calculating a global error between the reconstructed sound field and the target sound field based on the loudspeaker driving signal of the reconstructed target sound field;
and the optimal sound field reconstruction scheme selection module is used for selecting a target reconstruction scheme according to the global error between the reconstructed sound field and the target sound field.
Specifically, referring to fig. 1, the present invention provides an optimization system for sound field reconstruction, which includes a module 1: reestablishment speaker group data acquisition module, module 2: target sound field data acquisition module, module 3: sound field reconstruction error calculation module and module 4: and an optimal sound field reconstruction scheme selection module.
The module 1 is as follows: the module is used for acquiring the reconstructed loudspeaker group data, and aims to acquire a sound field formed at a target position by the sound wave emitted by the loudspeaker group under the driving of a unit signal under the current environment and arrangement after the action of environmental reflection, diffraction and the like. The method can be used for calculating the sound field generated under the drive of any signal. In particular applications, the data may be acquired at multiple target reconstruction locations. In the present example, the playback data of the speakers is collected at 1 position.
The module 2 is: and the target sound field data acquisition module is used for preprocessing the target sound field data, obtaining discrete sound pressure values under specific frequency after time-frequency transformation of the signals acquired at a plurality of discrete positions, and converting the discrete sound pressures into spherical harmonic coefficients under corresponding frequency by using a spherical harmonic conversion formula, so that the target sound field data acquisition module can be used for subsequent calculation. In a specific application, the position of the target sound field needs to be the same as the number of the collected sound field positions of the reconstructed loudspeaker group. In the present example, the target sound field data is sound field data at 1 position.
The module 3 is: and the sound field reconstruction error calculation module of the optimization system is used for adjusting the spherical harmonic coefficient matrix of the loudspeaker according to the selected spherical harmonic coefficient and preferentially reconstructing the selected spherical harmonic coefficient so as to obtain a corresponding reconstructed effect. In particular implementations, any spherical harmonic coefficient less than the total number of spherical harmonic coefficients may be selected for preferential reconstruction.
The module 4 is: and an optimal sound field reconstruction scheme selection module of the optimization system, wherein the optimal sound field reconstruction scheme selection module is used for selecting the optimal scheme with the lowest reconstruction error from all the possible schemes. The module selects a set of loudspeaker drive signals with the smallest reconstruction error at the target position from all the reconstruction errors obtained by the module 3 and uses the loudspeaker drive signals as an optimal reconstruction scheme for reconstructing the sound field.
Since the system described in the second embodiment of the present invention is a system used for implementing the sound field reconstruction optimization method based on the spherical harmonic selection in the first embodiment of the present invention, those skilled in the art can understand the specific structure and deformation of the system based on the method described in the first embodiment of the present invention, and thus the details are not described herein again. All systems adopted by the method of the first embodiment of the present invention are within the intended protection scope of the present invention.
It should be understood that parts of the specification not set forth in detail are well within the prior art.
It should be understood that the above description of the preferred embodiments is illustrative, and not restrictive, and that various changes and modifications may be made therein by those skilled in the art without departing from the scope of the invention as defined in the appended claims.
Claims (6)
1. A sound field reconstruction optimization method based on spherical harmonic selection is characterized by comprising the following steps:
s1: acquiring sound field data acquired by a reconstructed loudspeaker group at a target position under the excitation of a unit signal according to the arrangement of the reconstructed loudspeaker group in the current environment, and acquiring unit signal spherical harmonic coefficients of the loudspeaker group based on the acquired sound field data;
s2: acquiring sound field data to be reconstructed, taking the sound field data to be reconstructed as target sound field data, and performing spherical harmonic decomposition on the target sound field data to acquire corresponding spherical harmonic coefficients;
s3: reconstructing a loudspeaker driving signal of a target sound field according to the obtained unit signal spherical harmonic coefficient of the loudspeaker group and a target spherical harmonic coefficient selected from the spherical harmonic coefficients corresponding to the target sound field data, and calculating a global error between the reconstructed sound field and the target sound field based on the reconstructed loudspeaker driving signal of the target sound field;
s4: selecting a target reconstruction scheme according to the global error between the reconstructed sound field and the target sound field;
wherein S2 includes:
according to the sound pressure p of a target sound field at a specific position, acquiring a corresponding spherical harmonic coefficient according to a formula:
n is the order of the spherical harmonic coefficient, m is m coefficient subscripts under the spherical harmonic coefficient of the n order, x is the radius of the sound field corresponding to the target range,
for the position acquired by the microphone array at frequency f
Acoustic pressure of (a) < omega >qWeight corresponding to spherical integral, Q is number of microphones, jn(. is) a spherical Bessel function of order n, c is the speed of sound, Ynm(. cndot.) is the spherical harmonic, conjugate:
forming spherical harmonic coefficients of a target sound field into a vector:
β＝{β0,0(f),β1,-1(f),...,βn,n(f)},
wherein beta isn,mCorresponding to the collected spherical harmonic coefficient Cnm(f)。
2. The sound field reconstruction optimization method of claim 1, wherein the step S1 includes:
collecting a certain number of sound pressures p in a target range by using a microphone array with Q microphones, and acquiring corresponding spherical harmonic coefficients according to the following formula
Wherein n is the order of the spherical harmonic coefficient, m is the subscript of m coefficients under the spherical harmonic coefficient of n order, x is the sound field radius corresponding to the target range,
for the position acquired by the microphone array at frequency f
Acoustic pressure of (f), ωqWeights corresponding to spherical integrals, jn(. is) a spherical Bessel function of order n, c is the speed of sound, Ynm(. cndot.) is a spherical harmonic, conjugate,
Pn|m|(. cndot.) is a Legendre function, and θ, φ is a corresponding position
I is an imaginary number unit;
converting the spherical harmonic coefficients obtained from the loudspeaker signals into a matrix form:
wherein, the first and the second end of the pipe are connected with each other,
corresponding to the spherical harmonic coefficients collected by the loudspeakers numbered 1 to L
3. The sound field reconstruction optimization method of claim 2, wherein S3 specifically includes:
step S3.1: calculating a loudspeaker driving signal for reconstructing a target sound field according to a unit signal spherical harmonic coefficient of a loudspeaker group and a target spherical harmonic coefficient selected from spherical harmonic coefficients corresponding to target sound field data:
wherein S isLRepresenting loudspeaker drive signals for reconstructing a target sound field, HKRepresents a matrix formed by target spherical harmonic coefficients selected from spherical harmonic coefficients corresponding to target sound field data, betaKRepresenting a vector of selected k target coefficients,
is the pseudo-inverse of the matrix, and T is the vector transposition;
step S3.2: calculating spherical harmonic coefficients of the reconstructed sound field according to the loudspeaker driving signals of the reconstructed target sound field:
β′T＝HL×SL
wherein HLA matrix formed by spherical harmonic coefficients of the unit signal is represented;
step S3.3: calculating the global error between the reconstructed sound field and the target sound field according to the spherical harmonic coefficient of the reconstructed sound field,
wherein R is the radius of the target reconstruction sound field, the error function is integrated in the sphere of the whole target area,
is the sound pressure of the reconstructed sound field, and p (-) is the sound pressure of the target sound field, | | | is a1 norm, the spherical harmonic function is in place
The corresponding sound pressure can be calculated by the following formula:
x is
N is the order of the spherical harmonic coefficient.
4. The sound field reconstruction optimizing method of claim 1, wherein in step S3, the different reconstruction schemes are corresponding to each other based on the number and combination of the selected target spherical harmonic coefficients, and each reconstruction scheme corresponds to a reconstruction error, and the reconstruction error is a global error between the reconstructed sound field and the target sound field.
5. The sound field reconstruction optimization method according to claim 4, wherein the step S4 specifically includes:
according to the reconstruction errors corresponding to all the reconstruction schemes obtained in step S3, the scheme with the lowest global error is selected as the optimal reconstruction scheme:
wherein phiKAll the spherical harmonic coefficients of the reconstructed sound field calculated for preferentially reconstructing K spherical harmonic coefficients, N being the highest spherical harmonic order to be reconstructed, and beta' being the number phiKIn any scheme selected from (1), epsilon (beta ') is the sound field reconstruction error corresponding to the selected reconstruction scheme beta ', and the final optimal reconstruction scheme is beta 'minThe corresponding loudspeaker drive signal.
6. A system for optimizing sound field reconstruction based on spherical harmonic selection, comprising:
the device comprises a reconstruction loudspeaker group data acquisition module, a reconstruction loudspeaker group data acquisition module and a reconstruction loudspeaker group data acquisition module, wherein the reconstruction loudspeaker group data acquisition module is used for acquiring sound field data acquired by a target position of a reconstruction loudspeaker group under the excitation of a unit signal according to the arrangement of the reconstruction loudspeaker group under the current environment, and acquiring the unit signal spherical harmonic coefficient of the loudspeaker group based on the acquired sound field data;
the target sound field data acquisition module is used for acquiring sound field data to be reconstructed, taking the sound field data to be reconstructed as target sound field data, and performing spherical harmonic decomposition on the target sound field data to acquire corresponding spherical harmonic coefficients;
the sound field reconstruction error calculation module is used for reconstructing a loudspeaker driving signal of a target sound field according to the acquired unit signal spherical harmonic coefficient of the loudspeaker group and a target spherical harmonic coefficient selected from the spherical harmonic coefficients corresponding to the target sound field data, and calculating a global error between the reconstructed sound field and the target sound field based on the loudspeaker driving signal of the reconstructed target sound field;
the optimal sound field reconstruction scheme selection module is used for selecting a target reconstruction scheme according to the overall error between a reconstructed sound field and a target sound field;
the target sound field data acquisition module is specifically configured to:
according to the sound pressure p of a target sound field at a specific position, acquiring a corresponding spherical harmonic coefficient according to a formula:
n is the order of the spherical harmonic coefficient, m is m coefficient subscripts under the spherical harmonic coefficient of the n order, x is the radius of the sound field corresponding to the target range,
for the position acquired by the microphone array at frequency f
Acoustic pressure of (f), ωqWeight corresponding to the spherical integral, Q is the number of microphones, jn(. is) a spherical Bessel function of order n, c is the speed of sound, Ynm(. cndot.) is the spherical harmonic, conjugate:
forming spherical harmonic coefficients of a target sound field into a vector:
β＝{β0,0(f),β1,-1(f),...,βn,n(f)},
wherein beta isn,mCorresponding to the collected spherical harmonic coefficient Cnm(f)。
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