JP2017191980A - Sound field information parameter group generation device, method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sound source information parameter group generation technique capable of fixing the number of elements and the number of channels required for microphone array, or reducing the error of sound field information parameter groups generated.MEANS FOR SOLVING THE PROBLEM: A sound field information parameter group generation device includes a sound field information parameter group calculation unit 1 for calculating a sound field information parameter group on the basis of a signal obtained by collecting sounds generated from a sound source whose location is known with a microphone array, a movement action element calculation unit 2 calculating a movement action element for moving the origin of sound field information parameter, from the location of the sound source and the location of a microphone array, and an origin movement unit 3 for generating the calculated sound field information parameter group and a sound field information parameter group whose origin is moved from the calculated movement action element.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sound field recording technique for acquiring sound space information for sound field reproduction using a plurality of microphones.

  In the conventional sound field information parameter group generation apparatus, in order to acquire a sound field information parameter group at a position different from the installation position of the microphone array, the sound field information parameter group generation apparatus performs sound-space Fourier transform on the multichannel signal acquired by the microphone array. The field information parameter group is calculated, and the origin of the sound field information parameter group is moved by applying a method based on the addition theorem to the calculated sound field information parameter group (for example, non-patent) References 1 and 2).

Samarasinghe, P. N., et al., "3d spatial sound eld recording over large regions", Acoustic Signal Enhancement, Proceedings of IWAENC 2012, International Workshop on.VDE, pp. 1-4, 2012. Samarasinghe, PN, et al., "Spatial sound eld recording over a large area using distributed higher order microphones", Applications of Signal Processing to Audio and Acoustics (WASPAA), 2011 IEEE Workshop on.IEEE, pp. 221-224, 2011 .

  In the conventional sound field information parameter group generation device, when it is desired to acquire sound field information with a certain accuracy, the amount of information to be acquired by the microphone array increases as the estimated position moves away from the installation position, and the number of elements required for the microphone array In addition, the number of channels may increase.

  An object of the present invention is to provide a sound field information parameter group generation apparatus, method, and program capable of making the number of elements and the number of channels necessary for a microphone array constant or generating a small error in the generated sound field information parameter group. Is to provide.

  In order to solve the above-described problem, the sound field information parameter group generation device generates a sound field information parameter group based on a signal obtained by collecting sounds generated from a sound source whose position is known by a microphone array. A sound field information parameter group calculating unit to calculate, a moving operator calculating unit for calculating a moving operator for moving the origin of the sound field information parameter from the position of the sound source and the position of the microphone array, and the calculated sound field information parameter And an origin moving unit that generates a sound field information parameter group in which the origin is moved from the group and the calculated moving operator.

  The number of elements and the number of channels required for the microphone array can be made constant, or the error of the generated sound field information parameter group is reduced.

The functional block diagram which shows the example of a sound field information parameter group production | generation apparatus. The flowchart which shows the example of the sound field information parameter group production | generation method. The figure for demonstrating the coordinate system of 1st embodiment. The figure for demonstrating the coordinate system of 2nd embodiment.

  Embodiments of the present invention will be described below with reference to the drawings. In the following explanation, the symbols “^”, “→”, etc. used in the text should be written immediately above the character just before, but are written just before the character due to restrictions on the text notation. . In the formula, these symbols are written in their original positions. Further, the processing performed for each element of a vector or matrix is applied to all elements of the vector or matrix unless otherwise specified.

[Summary of Invention]
The sound field information parameter group generation apparatus and method acquire a sound field parameter group that is not a sound field around a recording location by using a sound field parameter group recorded at a certain point.

  Therefore, the sound field information parameter group generation apparatus and method assume that the position of the sound source existing in the actual space is known, and the moving operator necessary for moving the origin by using the sound source position information is obtained from the microphone array. The final sound field information parameter group is calculated from the calculated sound field information parameter group and the moving operator.

  That is, the sound field information parameter group calculation unit 1 calculates a sound field information parameter group based on a signal obtained by collecting sounds generated from a sound source whose position is known by a microphone array (step S1). . The moving operator calculation unit 2 calculates a moving operator for moving the origin of the sound field information parameter from the position of the sound source and the position of the microphone array (step S2). The origin moving unit 3 generates a sound field information parameter group in which the origin is moved from the calculated sound field information parameter group and the calculated moving operator (step S3).

  More specifically, in the sound field information parameter group generation apparatus and method, in order to acquire a sound field information parameter group at a position different from the installation position of the microphone array, a spatio-temporal Fourier transform is performed on the multichannel signal acquired by the microphone array. Then, the sound field information parameter group is calculated, and the origin of the sound field information parameter group is moved by applying a moving operator to the calculated sound field information parameter group. Assuming that the position of the sound source existing in the actual space is known, the moving operator necessary for moving the origin is the sound field information parameter group (“No. 1” generated when the omnidirectional sound source is assumed. A sound field information parameter (also referred to as a “second sound field information parameter group”) expressed based on the plane wave expansion and the phase conversion of the plane wave accompanying the movement of the origin. It is calculated based on a ratio with a sound field information parameter group generated when a sex sound source is assumed.

  That is, the sound field information parameter group calculation unit 1 calculates a sound field information parameter group by performing space-time Fourier transform on the signal (step S1). The moving operator calculation unit 2 includes the sound field information parameter group expressed based on the plane wave expansion of the sound field information parameter group generated when the omnidirectional sound source is assumed and the phase conversion of the plane wave accompanying the movement of the origin, The moving operator is calculated based on a ratio with a sound field information parameter group generated when a directional sound source is assumed (step S2). The origin moving unit 3 generates the sound field information parameter group in which the origin is moved by applying the calculated moving operator to the calculated sound field information parameter group (step S3).

  The first sound field information parameter group and the second sound field information parameter group may be calculated from signals recorded by the microphone array.

[function]
The functions used in the following description will be described.

N is the first real Hankel function H _n ⁽¹⁾ (•) and n-order Bessel function J _n (•) are defined as follows. Γ (z) is a gamma function, and Y _n (z) is a Neumann function. i is an imaginary unit.

The nth-order first-type sphere Hankel function h ⁽¹⁾ _n (•) and the nth-order sphere Bessel function j _n (•) are defined as follows. Note that the n-th order first-order sphere Hankel function h ⁽¹⁾ _n (•) may be simply abbreviated as an n-order sphere Hankel function h _n .

Is an arbitrary real number, and the second kind Hankel function H _n ⁽²⁾ (・) is expressed as follows using the first kind Bessel function J _n (x) ^# and the second kind Bessel function Y _n (x) Is defined as

Legendre 陪 function P ^m _n (•), defined as follows: P _n (·) represents a Legendre polynomial.

The spherical harmonic function Y _n ^m (·) is defined as follows.

[First embodiment]
The sound field information parameter group generation apparatus and method according to the first embodiment generate a sound field information parameter group based on a signal obtained by collecting sound with a spherical microphone array.

It is assumed that the sound space information is expressed in the spherical coordinate system illustrated in FIG. As illustrated in FIG. 3, the position of the sound field ^→ r = (r, θ, φ) is represented by a distance r from the origin O, an azimuth angle θ, and an elevation angle φ. ^→ r _s = (r _s , θ _s , φ _s ) is the position of the sound source. 0 ′ is the origin of the movement destination. ^→ T _{1 → 2} is ^→ T _{1 → 2} = O'-O, which is the movement vector of the origin. The origin O is also referred to as point (1), and the destination origin O ′ is also referred to as point (2).

  The sound field information parameter group generation apparatus and method of the first embodiment uses a spherical harmonic expansion coefficient of a sound field recorded at a certain point, and a spherical harmonic expansion coefficient of a sound field that is not a sound field around the recording location. In other words, the spherical harmonic expansion coefficient of the sound field at a position different from the installation position of the spherical microphone array is acquired. In the first embodiment, the sound field information parameter group is a spherical harmonic expansion coefficient.

  As shown in FIG. 1, the sound field information parameter group generation device includes, for example, a sound field information parameter group calculation unit 1, a movement operator calculation unit 2, and an origin movement unit 3. The sound field information parameter group generation method is realized by each part of the sound field information parameter group generation device executing, for example, the processing of step S1 to step S3 described below with reference to FIG.

<Sound field information parameter group calculation unit 1>
A signal obtained by collecting sound by the spherical microphone array is input to the sound field information parameter group calculation unit 1.

  The sound field information parameter group calculation unit 1 calculates a spherical harmonic expansion coefficient as a sound field information parameter group by performing spherical harmonic function conversion on the input signal (step S1). The calculated spherical harmonic expansion coefficient is output to the movement operator calculation unit 2 and the origin movement unit 3.

It is assumed that the sound field ψ _s ( ^→ r) recorded at a certain point is expressed by equation (1) using the spherical harmonic expansion coefficient B _nm .

  Here, N is a predetermined integer of 0 or more, and k is a wave number.

For example, for the multi-channel signal S acquired by the spherical microphone array, the spherical harmonic expansion coefficient B _nm of the sound field can be calculated using Equation (2) used in Reference Document 1.

Where i is the imaginary unit, a is the radius of the spherical microphone array, h ' _n is the derivative of the nth-order spherical Hankel function h _n , and p (a, θ, φ, ω) is the spherical microphone The sound pressure at the position (θ, φ, ω) of the wave with the angular frequency ω where the radius of the array is a, Y ^* _n ^m is the complex conjugate of the spherical harmonic function Y _n ^m .

Is an area and is defined by the following equation, for example.

  [Reference 1] M.A. Poletti, "Three-dimensional surround sound systems based on spherical harmonics", J. Audio Eng. Soc., Vol. 53, no. 11, pp. 1004-1025, 2005.

<Moving operator calculation unit 2>
The moving operator calculation unit 2 generates a spherical surface of a sound field expressed based on a plane wave expansion of a spherical harmonic expansion coefficient generated when a point sound source that is an omnidirectional sound source is assumed and a phase conversion of the plane wave accompanying the movement of the origin. The moving operator is calculated based on the ratio between the harmonic function expansion coefficient and the spherical harmonic function expansion coefficient generated when the omnidirectional sound source is assumed (step S2). The calculated moving operator is output to the origin moving unit 3.

For example, the moving operator calculation unit 3 is defined by the following equation (2 ′) of the spherical harmonic expansion coefficient _An ⁽²⁾ generated when a point sound source represented by the following equation (3) is assumed. Assuming that the point sound source is a spherical harmonic expansion coefficient _An ^{(1) of the} sound field expressed based on the plane wave expansion P _n (^ r · ^ r _s ) and the phase transformation of the plane wave accompanying the movement of the origin On the basis of the ratio with the spherical harmonic expansion coefficient A _n ⁽²⁾ generated in (5), O _nm is calculated for the above moving operator defined by the following equation (4).

Where Ψ _s ( ^→ r) is the sound field at position ^→ r = (r, θ, φ), ^ r is the ^→ r unit vector, and ^ r _s is the ^→ r _s unit vector , ^ K is the wave vector ^→ k unit vector, j ' _n is the derivative of the nth-order first-order spherical Bessel function, T _{1 → 2} is the size of the origin moving vector ^→ T _{1 → 2} Yes, ^ T _{1 → 2} is the unit vector of ^→ T _{1 → 2} , and π is the circumference.

The spherical harmonic expansion coefficient _An ⁽¹⁾ and the spherical harmonic expansion coefficient _An ⁽²⁾ can be defined by, for example, expressions (20) and (21) described later.

The moving operator calculation unit 3 calculates a spherical harmonic expansion coefficient A _nm ⁽¹⁾ and a spherical harmonic expansion coefficient A _nm ⁽²⁾ from signals recorded by a plurality of spherical microphone arrays, and these are calculated. Based on the spherical harmonic expansion coefficient A _nm ⁽¹⁾ and the spherical harmonic expansion coefficient A _nm ⁽²⁾ , the transfer operator O _nm = A _nm ⁽²⁾ / A _nm ⁽¹⁾ may be obtained. Note that sound fields derived from the same sound source at the same position may be separately recorded with one spherical microphone array and used in synchronization with each other.

<Origin mover 3>
Origin movement unit 3, the sound field to the information parameter groups 1 sound field information parameter group that has been calculated, the sound field origin is moved by applying a moving operator O _nm calculated by the mobile operator calculating unit 2 An information parameter group is generated (step S3).

  With the above configuration, if the actual sound source is a point sound source and the sound source position is assumed to be the same, if you want to acquire sound field information with a certain degree of accuracy, use the microphone array regardless of the distance between the estimated position and the installation position. The amount of information to be fixed is constant, and the number of elements and channels required for the microphone array are constant. However, the actual sound source is not necessarily a point sound source, and the assumed sound source position may be different from the actual sound source position. Even in such a case, if the actual sound source can be approximated to a point sound source and the position of the sound source is close to the assumed position, the error of the sound field information parameter group can be reduced.

  Note that the sound field information parameter group is used for single-region sound field reproduction (higher-order ambinonics (for example, References 1 to 2)) and various multi-region sound field reproduction (references 3 to 5). Can do.

[Reference 2] EG Williams, "Fourier Acoustics: Sound Radiation and Near eld Acoustical Holography", London UK, Academic Press, 1999.
[Reference 3] Terence B., "Theory and design of sound eld reproduction in reverberant rooms", J. Acoust. Soc. Am., Vol. 117, no. 4, pp. 2100-2111, 2005.
[Reference 4] Wu, YJ, et al., "Spatial Multizone Sound eld Reproduction: Theory and Design", IEEE Trans. Audio, Speech, Lang. Process., Vol. 19, no. 6, pp. 1711-1720 , 2011.
[Reference 5] Zha, M, et al., "3D multizone sound eld reproduction using spherical harmonic analysis", Signal and Information Processing (ChinaSIP), 2015 IEEE China Summit and International Conference on.IEEE, vol. 53, no. 11, pp. 625-629, 2015.

  Note that the prior art does not assume that the position of the sound source is known, but assumes that the position of the sound source is unknown. For this reason, there is no effect in the prior art because the position and orientation characteristics of the sound source deviate from the assumptions of the present invention.

[Second Embodiment]
The sound field information parameter group generation apparatus and method according to the second embodiment generate a sound field information parameter group based on a signal obtained by collecting sound with a cylindrical microphone array.

It is assumed that the sound space information is expressed in the coordinate system illustrated in FIG. As illustrated in FIG. 4, the position of the sound field ^→ r = (r, θ) is represented by a distance r from the origin O and an azimuth angle θ. ^→ r _s = (r _s , θ _s ) is the position of the sound source. 0 ′ is the origin of the movement destination. ^→ T _{1 → 2} is ^→ T _{1 → 2} = O'-O, which is the movement vector of the origin. The origin O is also referred to as point (1), and the destination origin O ′ is also referred to as point (2).

  The sound field information parameter group generation apparatus and method of the second embodiment uses a cylindrical harmonic function expansion coefficient of a sound field recorded at a certain point, and a cylindrical harmonic function expansion coefficient of a sound field that is not a sound field around the recording location. In other words, the cylindrical harmonic function expansion coefficient of the sound field at a position different from the installation position of the cylindrical microphone array is acquired. In the second embodiment, the sound field information parameter group is a cylindrical harmonic function expansion coefficient.

  As shown in FIG. 1, the sound field information parameter group generation device includes, for example, a sound field information parameter group calculation unit 1, a movement operator calculation unit 2, and an origin movement unit 3. The sound field information parameter group generation method is realized by each part of the sound field information parameter group generation device executing, for example, the processing of step S1 to step S3 described below with reference to FIG.

<Sound field information parameter group calculation unit 1>
A signal obtained by collecting sound by the cylindrical microphone array is input to the sound field information parameter group calculation unit 1.

  The sound field information parameter group calculation unit 1 calculates a cylindrical harmonic function expansion coefficient as a sound field information parameter group by performing cylindrical harmonic function conversion on the input signal (step S1). The calculated cylindrical harmonic function expansion coefficient is output to the moving operator calculating unit 2 and the origin moving unit 3.

It is assumed that the sound field ψ _s ( ^→ r) recorded at a certain point is expressed by equation (1) using the cylindrical harmonic function expansion coefficient B _n .

  Here, N is a predetermined integer greater than or equal to 0, k is a wave number, and j is an imaginary unit.

For example, the cylindrical harmonic function expansion coefficient B _n of the sound field can be calculated for the multi-channel signal S acquired by the cylindrical microphone array using the equation (2) used in Reference Document 6.

Where i is the imaginary unit, a is the radius of the cylindrical microphone array, H ′ _n ⁽²⁾ is the derivative of the nth-order second-class Hankel function H _n ⁽²⁾ , and p (a, θ, z, ω) is the sound pressure at the position (a, θ, z, ω) of the wave of angular frequency ω, where a is the radius of the cylindrical microphone array, and f (z) is the integral in the z direction. Is a weight function.

Is a line integral and is defined by the following equation, for example.

  [Reference 6] Shimizu, T., et al., "A multi-zone approach to sound eld reproduction based on spherical harmonic analysis", Acoustical Science and Technology, vol. 36, no. 5, pp. 441-444, 2015.

<Moving operator calculation unit 2>
The moving operator calculation unit 2 is a cylinder of a sound field expressed based on a plane wave expansion of a cylindrical harmonic function expansion coefficient generated when a line sound source that is an omnidirectional sound source is assumed and a phase conversion of the plane wave accompanying the movement of the origin. The moving operator is calculated based on the ratio between the harmonic function expansion coefficient and the cylindrical harmonic function expansion coefficient generated when the omnidirectional sound source is assumed (step S2). The calculated moving operator is output to the origin moving unit 3.

For example, the moving operator calculation unit 3 is defined by the following equation (6 ′) of the cylindrical harmonic function expansion coefficient _An ⁽²⁾ generated when the line sound source represented by the following equation (7) is assumed. Assuming a plane harmonic expansion D _n (^ r · ^ r _s ) and a cylindrical harmonic function expansion coefficient _An ^{(1) of the} sound field expressed based on the phase transformation of the plane wave accompanying the movement of the origin, and the above line source the mobile operator, which is defined by a cylindrical harmonic expansion coefficients a _n ⁽²⁾ based on the ratio of the following equation is generated (4) to calculate the O _n.

Where Ψ _s ( ^→ r) is the sound field at position ^→ r = (r, θ), ^ r is the ^→ r unit vector, ^ r _s ^→ r _s unit vector, ^ k is the wave vector ^→ unit vector of k, J ' _n is the derivative of the nth-order Bessel function J _n , T _{1 → 2} is the magnitude of the origin moving vector ^→ T _{1 → 2} , and ^ T _{1 → 2} is a unit vector of ^→ T _{1 → 2} and π is a circumference.

The cylindrical harmonic function expansion coefficient _An ⁽¹⁾ and the cylindrical harmonic function expansion coefficient _An ⁽²⁾ can be defined by, for example, expressions (37) and (38) described later.

The moving operator calculation unit 3 calculates the cylindrical harmonic function expansion coefficient A _nm ⁽¹⁾ and the cylindrical harmonic function expansion coefficient A _nm ⁽²⁾ from signals recorded by a plurality of cylindrical microphone arrays, and these are calculated. Based on the cylindrical harmonic expansion coefficient A _nm ⁽¹⁾ and the cylindrical sum function expansion coefficient A _nm ⁽²⁾ , the transfer operator O _nm = A _nm ⁽²⁾ / A _nm ⁽¹⁾ may be obtained. Note that sound fields derived from the same sound source at the same position may be separately recorded with one cylindrical microphone array and used in synchronization with time.

<Origin mover 3>
Origin movement unit 3, the sound field to the information parameter groups 1 sound field information parameter group that has been calculated, the sound field origin is moved by applying a moving operator O _nm calculated by the mobile operator calculating unit 2 An information parameter group is generated (step S3).

  With the above configuration, if the actual sound source is a point sound source and the sound source position is assumed to be the same, if you want to acquire sound field information with a certain degree of accuracy, use the microphone array regardless of the distance between the estimated position and the installation position. The amount of information to be fixed is constant, and the number of elements and channels required for the microphone array are constant. However, the actual sound source is not necessarily a point sound source, and the assumed sound source position may be different from the actual sound source position. Even in such a case, if the actual sound source can be approximated to a point sound source and the position of the sound source is close to the assumed position, the error of the sound field information parameter group can be reduced.

  Note that the sound field information parameter group is used for single-region sound field reproduction (higher-order ambinonics (for example, References 1 to 2)), various multi-region sound field reproduction (references 3 to 5), and the like. Can do.

  The prior art does not assume that the position of the sound source is known, but assumes that the position of the sound source is unknown. For this reason, there is no effect in the prior art because the position and orientation characteristics of the sound source deviate from the assumptions of the present invention.

[Derivation of Equation (4)]
Hereinafter, the reason why the moving operator for the spherical harmonic expansion coefficient of the sound field derived from the point sound source can be described, for example, as in Equation (4) will be described.

(Assumption)
A spherical harmonic function of a plane wave is expressed as follows (for example, see Reference 1).

  A spherical harmonic function expression of a point sound source is expressed as follows (for example, see Reference 1).

  The addition theorem of spherical harmonics is expressed as follows (for example, see Reference 2).

  The orthogonality of the Legendre polynomial is expressed as follows (for example, see Reference 2).

(Sound field representation by Legendre polynomial)
When formula (11) is introduced in formula (9), it becomes as follows.

  When Expression (11) is introduced in Expression (10), the following is obtained.

(Plane wave expansion of Legendre polynomial)
The coordinates of the observation point appear as arguments of the spherical Bessel function and Legendre polynomial in the right side of Equation (13) and Equation (14). The plane wave expansion for the Legendre polynomial (or the Fourier transform in the Cartesian coordinate system) is calculated as follows using equations (12) and (13).

  From equation (15), the following identity for the Legendre polynomial is obtained.

(Movement operator for plane wave sound field)
From Equation (9), the sound field corresponding to the plane wave can be moved by simple phase correction.

(Sound field moving operator by point source)
By introducing the equation (16) into the equation (14), the following equation is obtained.

  The coordinates of the observation point in Equation (18) are plane wave sound fields.

Appears only as part of These can be moved by applying equation (17), and the following equation can be obtained.

  The nth-order term of the spherical harmonic expansion of Equation (19) is as follows.

  These terms are terms for the expansion at the origin in (14).

Can be compared.

  The moving operator between observation points (1) and (2) for the spherical harmonic expansion coefficient of the sound field derived from a point source is defined by the ratio of Eqs. (20) and (21).

  When equation (13) is introduced in equation (22), the equation of the transfer operator related to the expansion coefficients of points (1) and (2) is as follows.

[Derivation of Equation (8)]
Hereinafter, the reason why the moving operator for the cylindrical harmonic function expansion coefficient of the sound field derived from the line sound source can be described, for example, as in Expression (8) will be described.

(Assumption)
The cylindrical harmonic function of a plane wave that propagates horizontally is expressed as follows (for example, see Reference 2).

  The cylindrical harmonic function of a linear sound source parallel to the z-axis is expressed as follows (for example, see Reference 2).

  For the sake of brevity, the partial delta function is defined as follows:

  The exponent format of the Kronecker Delta is expressed as follows:

(Sound field representation by partial delta function)
When formula (28) is introduced in formula (26), it becomes as follows.

  When equation (28) is introduced in equation (27), it becomes as follows.

(Plane wave expansion of partial delta function)
The plane wave expansion (or Fourier transform in the Cartesian coordinate system) for the partial delta function in which the coordinates of the observation point appear as arguments of the Bessel function and the partial delta function on the right side of Equations (30) and (31) is given by Equations (29) and ( 30) can be used to calculate.

  From equation (32), the following identity for the partial delta function is obtained.

(Movement operator for plane wave sound field (2D))
From Equation (26), the sound field corresponding to a plane wave can be moved by basic phase correction.

(Moving operator for a sound field on a horizontal plane by a vertical sound source)
Substituting equation (33) into equation (31) yields:

  The coordinates of the observation point in Equation (35) are plane wave sound fields.

Appears only as part of These can be moved by the equation (34), and the following equation can be obtained.

  In the nth order term in the cylindrical harmonic expansion of Eq. (36),

These terms are terms for the expansion at the origin in (31).

Can be compared.

  The moving operator between observation points (1) and (2) for the cylindrical harmonic expansion coefficient of the sound field on the horizontal plane derived from the vertical line source is the ratio between Eqs. (37) and (38). Defined by

  When equation (30) is introduced in equation (39), the equation of the transfer operator relating to the expansion coefficient for points (1) and (2) is as follows.

[Program and recording medium]
The sound field information parameter group generation device can be realized by a computer. In this case, the processing content of each part of this apparatus is described by a program. Then, by executing this program on a computer, each unit in this apparatus is realized on the computer.

  The program describing the processing contents can be recorded on a computer-readable recording medium. In this embodiment, these apparatuses are configured by executing a predetermined program on a computer. However, at least a part of these processing contents may be realized by hardware.

[Modification]
The present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit of the present invention.

  For example, the formulas given in the first embodiment and the second embodiment are examples. In the first embodiment and the second embodiment, the same effect can be obtained even if expressions derived by other methods are used.

Claims (9)

A sound field information parameter group calculation unit that calculates a sound field information parameter group based on a signal obtained by collecting sound generated by a sound source having a known position with a microphone array;
A moving operator calculator for calculating a moving operator for moving the origin of the sound field information parameter from the position of the sound source and the position of the microphone array;
An origin moving unit that generates a sound field information parameter group in which the origin is moved from the calculated sound field information parameter group and the calculated moving operator;
A sound field information parameter group generation device including In the sound field information parameter group generation device according to claim 1,
The sound field information parameter group calculation unit calculates a sound field information parameter group by performing a spatio-temporal Fourier transform on the signal,
The moving operator calculation unit includes the sound field information parameter group expressed based on the plane wave expansion of the sound field information parameter group generated when the omnidirectional sound source is assumed and the phase conversion of the plane wave accompanying the movement of the origin, Calculate the moving operator based on the ratio to the sound field information parameter group generated when assuming a directional sound source,
The origin moving unit generates a sound field information parameter group in which the origin is moved by applying the calculated moving operator to the calculated sound field information parameter group.
Sound field information parameter group generation device. The sound field information parameter group generation device according to claim 2,
The sound field information parameter group calculation unit calculates a spherical harmonic function expansion coefficient as a sound field information parameter group by performing spherical harmonic function transformation on the signal,
The moving operator calculation unit includes a plane harmonic expansion of a spherical harmonic expansion coefficient generated when a point sound source is assumed and a spherical harmonic expansion coefficient of the sound field expressed based on a phase conversion of the plane wave accompanying the movement of the origin and the above Calculate the moving operator based on the ratio with the spherical harmonic expansion coefficient generated when assuming a point sound source,
The origin moving unit generates a sound field information parameter group in which the origin is moved by applying the calculated moving operator to the calculated spherical harmonic expansion coefficient.
Sound field information parameter group generation device. The sound field information parameter group generation device according to claim 2,
The sound field information parameter group calculation unit calculates a cylindrical harmonic function expansion coefficient as a sound field information parameter group by performing a cylindrical harmonic function transformation on the signal,
The moving operator calculation unit includes a plane harmonic expansion of a cylindrical harmonic function expansion coefficient generated when a linear sound source is assumed, and a cylindrical harmonic function expansion coefficient of a sound field expressed based on a phase conversion of the plane wave accompanying the movement of the origin and the above Calculate the moving operator based on the ratio with the cylindrical harmonic expansion coefficient generated when a line sound source is assumed,
The origin moving unit generates a sound field information parameter group in which the origin is moved by applying the calculated moving operator to the calculated cylindrical harmonic function expansion coefficient.
Sound field information parameter group generation device. In the sound field information parameter group generation device according to claim 3,
i is an imaginary unit, k is a wave number, the microphone array is a spherical microphone array, a is a radius of the spherical microphone array, θ is an azimuth angle, φ is a levitating angle, ω is a frequency, and h ′ _n Is the derivative of the n-th order spherical Hankel function h _n , p is the sound pressure, Y ^* _n ^m is the complex conjugate of the spherical harmonic function Y _n ^m , and the sound field information parameter group calculation unit The spherical harmonic expansion coefficient B _nm defined by the following equation (2) is calculated as a sound field information parameter group by performing spherical harmonic transformation,

The P _n and Legendre polynomials, Ψ _s ^(→ r) the position ^{→ r = (r, θ,} φ) and the sound field in, the unit vector of ^ the _{^{r → r, → r s =}} (r s, θ s , the φ _s) and position of the sound source, ^ a r _s is a unit vector of ^→ r _s, the j _n as the n-th order spherical Bessel function, h _n a ⁽¹⁾ and the n-th order of the first kind Hankel function, ^ Let k be the wave vector ^→ the unit vector of k, j ' _{n be} the derivative of the first-order spherical Bessel function of the nth order, T _{1 → 2} be the origin movement vector ^→ T _{1 → 2} and ^ T _{1 → 2} as a unit vector in ^→ T _{1 → 2,} the mobile operator calculating unit has the following formula in the spherical harmonic expansion coefficients a _nm generated when assuming a point sound source which is represented by (3) ⁽²⁾ Plane wave expansion P _n (^ r ・ ^ r _s ) defined by the following equation (2 ') and the spherical harmonic expansion coefficient A _nm ^{(1 of the} sound field expressed based on the phase transformation of the plane wave accompanying the movement of the origin ⁾ and the sphere which is generated when assuming the point source The mobile operator, which is defined by the harmonic expansion coefficients A _nm ⁽²⁾ a ratio Based on the following equation (4) to calculate the O _nm,

The origin moving unit generates a sound field information parameter group in which the origin is moved by applying the calculated moving operator O _nm to the calculated spherical harmonic expansion coefficient B _nm .
Sound field information parameter group generation device. In the sound field information parameter group generation device according to claim 4,
where i and j are imaginary units, k is the wave number, the microphone array is a cylindrical microphone array, a is the radius of the cylindrical microphone array, θ is the azimuth angle, φ is the leap angle, and ω is the frequency. , H ′ _n ⁽²⁾ is the derivative of the nth-order second-class Hankel function H _n ⁽²⁾ , p is the sound pressure, and the sound field information parameter group calculation unit converts the harmonic signal into a cylindrical harmonic function To calculate a cylindrical harmonic function expansion coefficient B _n defined by the following equation (6) as a sound field information parameter group,

The sound field in Ψ _s ^(→ r) the position ^{→ r = (r, θ)} , ^ the r ^→ is a unit vector of _{^{r, → r s = (r}} s, θ s) was used as a location of the sound source, ^ k Is a wave vector ^→ k unit vector, ^ r _s ^→ r _s unit vector, H ' _n ⁽¹⁾ is an n-th order Hankel function, J _n is an n-order Bessel function, J 'the _n and derivative of J _n, the size Satoshi of T _{1 → 2} origin motion vector ^→ T _{1 → 2,} the unit vector ^ T _{1 → 2} a ^→ T _{1 → 2,} the mobile operator calculating unit, Plane wave expansion D _n (^ r, which is defined by the following equation (6 ') of the cylindrical harmonic function expansion coefficient A _n ⁽²⁾ generated when the line sound source represented by the following equation (7) is assumed: ^ r _s ) and the cylindrical harmonic function expansion coefficient A _n ^{(1) of the} sound field expressed based on the phase transformation of the plane wave accompanying the movement of the origin and the cylindrical harmonic function expansion coefficient A generated when the above point sound source is assumed defined by equation (8) below on the basis of the ratio of the _n ⁽²⁾ The mobile operator calculates the O _nm to,

The origin movement section, the origin generates movement sound field information parameter group by applying a moving operator O _n which is the calculated to the cylindrical harmonic expansion coefficients B _n, which is the calculated,
Sound field information parameter group generation device. A sound field information parameter group calculation step in which the sound field information parameter group calculation unit calculates a sound field information parameter group based on a signal obtained by collecting sounds generated from a sound source having a known position by a microphone array. When,
A moving operator calculating unit that calculates a moving operator for moving the origin of the sound field information parameter from the position of the sound source and the position of the microphone array;
An origin moving unit that generates a sound field information parameter group in which the origin is moved from the calculated sound field information parameter group and the calculated moving operator;
Sound field information parameter group generation method including The sound field information parameter group generation method according to claim 7,
The sound field information parameter group calculation unit calculates a sound field information parameter group by performing a spatio-temporal Fourier transform on the signal,
The moving operator calculation unit includes the sound field information parameter group expressed based on the plane wave expansion of the sound field information parameter group generated when the omnidirectional sound source is assumed and the phase conversion of the plane wave accompanying the movement of the origin, Calculate the moving operator based on the ratio to the sound field information parameter group generated when assuming a directional sound source,
The origin moving unit generates a sound field information parameter group in which the origin is moved by applying the calculated moving operator to the calculated sound field information parameter group.
Sound field information parameter group generation method.   A sound field information parameter group generation program for causing a computer to function as each part of the sound field information parameter group generation device according to any one of claims 1 to 6.

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