Patent Translate Powered by EPO and Google Notice This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate, complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or financial decisions, should not be based on machine-translation output. DESCRIPTION JP2017055156 Abstract: To provide a sound field measurement technique for measuring a sound field with high accuracy using spherical wave spectra of a plurality of spherical microphone arrays. SOLUTION: The nearest microphone determination unit which determines the spherical microphone array closest to the origin of the coordinate system O using the arrangement position of the spherical microphone array, and the layout position of the spherical microphone array closest to the origin of the coordinate system O A relative power error calculation unit that calculates a relative power error, and a spherical microphone array that determines a spherical microphone array that uses a predetermined range that indicates that the relative power error is small as the spherical microphone array that is used to calculate the mutual conversion matrix T (k) An identifier selection unit is included. [Selected figure] Figure 7 Sound field measurement device, sound field measurement method, program [0001] The present invention relates to sound field measurement technology, and in particular to measuring a wide range of sound field using a plurality of spherical microphone arrays. [0002] In recent years, audio reproduction technology has been expanded from 2-channel stereo to 5.1channel reproduction, and further, research and development of 22.2 channel reproduction and wavefront synthesis have been advanced. 03-05-2019 1 The purpose is to greatly improve the realism of the reproduction itself and to expand the reproduction area with high realism as much as possible. [0003] In order to evaluate and verify such a multi-channel audio reproduction method, it is important to measure the reproduced sound field. For example, in the wave-field synthesis method, it is necessary to compare the actually recorded sound field with the reproduced sound field to grasp the difference. The reason is that various factors such as signal processing for converting the recorded sound field into reproduced signals, encoding and decoding of the recorded signals, and acoustic characteristics of the room in which the reproducing apparatus is installed affect the reproduction accuracy of the sound field. . In order to establish a method with high reproduction accuracy of the sound field, it is important to measure the sound field accurately first. [0004] There are several conventional methods for measuring the sound field. Hereinafter, conventional methods will be described. (Prior Art 1) The first method is a method of closely arranging microphones at regular intervals in an area to be measured and measuring a sound field. In this method, for example, 400 microphones are required to arrange the microphones in a twodimensional grid of 20 points in length and width. At the same time as the number of microphones and associated cables is large, the area also occupies a considerable volume. From the viewpoint of the sound field, a large amount of microphones and cables themselves become disturbance factors of the sound field, and the difference between the measured sound field and the originally desired sound field, that is, the sound field without the measurement system can not be ignored. I will. (Conventional Technique 2) The following method is a method of locally arranging a microphone locally on a part of a target measurement area, and estimating the sound field of the entire measurement area from the measurement results. As such a method, a sound field measurement method using a spherical microphone array has been proposed (Non-Patent Document 1). The spherical microphone array is a microphone array configured by arranging several tens or more of microphone elements on a spherical surface with a radius of several cm to several tens of cm. [0005] 03-05-2019 2 Hereinafter, the method described in Non-Patent Document 1 will be described. The method described in Non-Patent Document 1 measures the sound field generated by a sound source located outside the measurement area, that is, deals with an internal problem. A coordinate system whose origin is the arrangement position of the spherical microphone array (the center of the spherical microphone array) is O 0, and the coordinates of the point x are represented by polar coordinates (r, θ, φ). At this time, the sound field at frequency f at point x of polar coordinates (r, θ, φ), that is, the sound field S (x, k) at the corresponding wave number k = 2πf / c (where c is the speed of sound) Is [0006] [0007] It can be expressed as Here, j n (·) is a spherical Bessel function of n-th order, and Y nm (·) is a spherical harmonic function of order n and m. Further, a <(0)> nm (k) is called a spherical wave spectrum, and is a coefficient representing a sound field in the coordinate system O 0 for each frequency (for each wave number). a <(0)> nm (k) is also called a sound field coefficient. [0008] Therefore, if a <(0)> nm (k) is known, the sound field is determined in a fixed range near the origin of the coordinate system O 0 (that is, the arrangement position of the spherical microphone array) by using (Equation 1) be able to. [0009] Hereinafter, the outline of the sound field measurement device 800 of Non-Patent Document 1 will be described with reference to FIGS. FIG. 1 is a block diagram showing the configuration of the sound field measurement device 800 of Non-Patent Document 1. As shown in FIG. FIG. 2 is a flowchart showing the operation of the 03-05-2019 3 sound field measurement apparatus 800 of Non-Patent Document 1. As shown in FIG. 1, the sound field measurement apparatus 800 of Non-Patent Document 1 includes a short time Fourier transform unit 810 and a spherical wave spectrum calculation unit 820. Also, the spherical microphone array 850 for recording the sound field is outside the sound field measurement device 800. The sound field measurement device 800 of Non-Patent Document 1 obtains a spherical wave spectrum a <(0)> nm (k) from a collected sound signal recorded using a spherical microphone array 850. [0010] The short-time Fourier transform unit 810 performs a short-time Fourier transform from the collected sound signal recorded using the spherical microphone array 850, that is, the signal collected by each microphone element arranged on the spherical surface of the spherical microphone array 850. An area signal is calculated (S810). The spherical wave spectrum calculation unit 820 calculates a spherical wave spectrum a <(0)> nm (k) from the frequency domain signal (S820). [0011] Hereinafter, the process in the spherical wave spectrum calculation unit 820 will be described in detail. Assuming that the radius of the spherical microphone array 850 is r 0, the sound field S (x, k) at a point x (r 0, θ, φ) on the sphere of radius r 0 is given by (Equation 1) [0012] [0013] It is written as Here, about spherical harmonics Y nm (·) [0014] 03-05-2019 4 [0015] The orthogonal relationship of From (Equation 2) and (Equation 3) [0016] [0017] Is obtained. Theoretically, the spherical wave spectrum a <(0)> nm (k) can be determined by calculating the integral, but in reality, the microphone elements arranged on the spherical surface of the spherical microphone array 850 The spherical wave spectrum a <(0)> nm (k) must be determined from the collected signal. Therefore, assuming that the number of the microphone elements is D, and the polar coordinates of the position x d of the microphone elements are (r 0, θ d, φ d) (1 ≦ d ≦ D), the integration is replaced with the product sum to obtain the spherical wave spectrum a Calculate <(0)> nm (k). [0018] [0019] Where w d is a properly set weight. [0020] As described above, the process of calculating the spherical wave spectrum a <(0)> nm (k) using (Equation 4) is the process performed by the spherical wave spectrum calculation unit 820. 03-05-2019 5 (Conventional Technique 3) As described above, spherical microphone arrays are mostly in the case of a few cm to a few dozen cm in radius, and the range of the sound field that can be measured often stays within several tens cm. Therefore, in order to measure a wider range of sound field, a method has been proposed in which a plurality of spherical microphone arrays are dispersively arranged and the sound field is estimated therefrom (Non-patent Document 2). According to this method, it is also possible to measure the sound field at an intermediate position between the spherical microphone array and the spherical microphone array, and it becomes possible to measure a wide range of sound field while keeping the number of spherical microphone arrays installed small. . [0021] Hereinafter, the method described in Non-Patent Document 2 will be described. Similar to the method described in Non-Patent Document 1, the method described in Non-Patent Document 2 measures the sound field generated by a sound source located outside the measurement area, that is, deals with an internal problem. [0022] Hereinafter, the outline of the sound field measurement apparatus 900 of Non-Patent Document 2 will be described with reference to FIGS. 3 to 4. Note that components having the same function will be assigned the same reference numerals and redundant description will be omitted. FIG. 3 is a block diagram showing the configuration of the sound field measurement device 900 of Non-Patent Document 2. As shown in FIG. FIG. 4 is a flowchart showing the operation of the sound field measurement apparatus 900 of Non-Patent Document 2. As shown in FIG. 3, the sound field measurement apparatus 900 of Non-Patent Document 2 includes a short time Fourier transform unit 810, a spherical wave spectrum calculation unit 820, a position measurement unit 910, a T calculation unit 920, and an integration unit 930. Including. A spherical microphone array 850 for recording the sound field is outside the sound field measurement device 900. Further, the short-time Fourier transform unit 810 and the spherical wave spectrum calculation unit 820 have the same number as that of the spherical microphone array 850 in a form corresponding to the spherical microphone array 850. There are Q spherical microphone arrays 850, and an identifier q is given to identify each of them (Q is an integer of 1 or more, 1 ≦ q ≦ 03-05-2019 6 Q). [0023] Let O 0 be a coordinate system whose origin is the center of the sound field to be estimated. Further, a coordinate system having an arrangement position of the spherical microphone array 850 of the identifier q (the center of the spherical microphone array 850 of the identifier q) as an origin is set to O q. The postures of the respective coordinate systems, that is, the directions of the xyz axes coincide with each other, and can be superimposed only by translational movement. Also, polar coordinates are used for all coordinate systems. [0024] Sound field measurement apparatus 900 of Non-Patent Document 2 is a spherical wave spectral vector in coordinate system O 0 whose origin is the center of the sound field to be estimated from a collected sound signal recorded using Q spherical microphone arrays 850. It is to obtain B (k). [0025] The position measurement unit 910 measures the position in the coordinate system O 0 of the arrangement position (center) of the Q spherical microphone arrays 850 arranged in the space (S 910). For example, a method of estimating the position from a plurality of camera images may be used based on the principle of triangulation. The arrangement position of the spherical microphone array 850 of the identifier q, that is, polar coordinates in the coordinate system O 0 of the origin of the coordinate system O q is (R q, Θ q, q q) (1 ≦ q ≦ Q). [0026] The T calculation unit 920 calculates a spherical wave from a spherical wave spectral vector A <(q)> (k) (where 1 q q Q Q) calculated from a collected sound signal recorded using Q spherical microphone arrays 850. The mutual conversion matrix T (k) used to calculate the spectral vector 03-05-2019 7 B (k) is calculated using polar coordinates (R q, Θ q, q q) in the coordinate system O 0 of the origin of the coordinate system O q ( S920). The spherical wave spectral vector A <(q)> (k) is obtained from the spherical wave spectrum when polar coordinate display in the coordinate system O q is used, and the spherical wave spectrum is calculated by the method described in Non-Patent Document 1 do it. The integration unit 930 calculates a spherical wave spectral vector B (k) from the spherical wave spectral vector A <(q)> (k) (where 1 ≦ q ≦ Q) and the mutual conversion matrix T (k) (S930) ). [0027] Hereinafter, processing in the T calculation unit 920 and the integration unit 930 will be described in detail. (Processing in T calculation unit 920) Let polar coordinates of point x in coordinate system O 0 be (R, Θ, Φ), polar coordinates in coordinate system O q be (r, θ, φ), and consider a sound field at point x . Let S (x, k) be a sound field at wave number k of point x in coordinate system O 0, and S q (x, k) be a sound field at wave number k of point x in coordinate system O q. Since the polar coordinate display in the coordinate system O 0 of the point x is (R, Θ,)), [0028] [0029] It is expressed as On the other hand, the polar coordinate display of the point x in the coordinate system O q is (r, θ, φ), [0030] [0031] It is expressed as 03-05-2019 8 (Equation 5) and (Equation 6) represent the same sound field except that the coordinate system is different. Therefore, the relationship between the spherical wave spectrum a <(0)> nm (k) and a <(q)> νμ (k) is examined. [0032] From the addition theory of spherical Bessel functions and spherical harmonics, [0033] [0034] Is established (r = R−Rq). ここで、 [0035] [0036] である。 Also, W 1 and W 2 are Wigner's 3j symbols, respectively [0037] [0038] 03-05-2019 9 である。 The values of W 1 and W 2 can be calculated by the method described in (Reference Non-Patent Document 3). (Reference non-patent document 3: A. Messiah, "Messiah Quantum Mechanics 2", Tokyo Books Co., Ltd., 1972, Appendix C, pp. 269-275. ) (Eq. 5), (Eq. 6) and (Eq. 7), [0039] となる。 [0040] Spherical wave spectrum a <(0)> nm (k) in the coordinate system O 0, spherical wave spectrum a <(q)> μμ in the coordinate system O q, where N is the expansion order of (Equation 5) and (Equation 6) The spherical wave spectral vector B (k) determined from (k) and the spherical wave spectral vector A <(q)> (k) [0041] [0042] Then, the relationship between B (k) and A <(q)> (k) is described as follows using T <(q)> (k). [0043] [0044] さらに、１≦ｑ≦Ｑであることから、 [0045] [0046] Is established. 03-05-2019 10 [0047] From the above, the process of calculating the matrix T (k) using (Equation 8), (Equation 9-1), and (Equation 9-2) is the process performed by the T calculation unit 920. (Processing in Integration Unit 930) The integration unit 930 calculates B (k) using the following (Expression 10). [0048] [0049] However, T (k) <H> is an adjoint matrix of T (k). [0050] Thushara D. Abhayapala and Darren B. Ward, "Theory and design of high order sound field microphones using spherical microphone array", in Proc. Acoustics, Speech, and Signal Processing (ICASSP), IEEE International Conference on, IEEE, 2002, vol. II, pp. II-1949. Prasanga N. Samarasinghe, Thushara D. Abhayapala and M.A. Poletti, "3D spatial soundfield recording over large regions", International Workshop on Acoustics Signal Enhancement 2012, IEEE, 4-6 Sep. 2012, pp. 1-4. 03-05-2019 11 [0051] The prior art 3 deals with an ideal state in which there is no error in spherical wave spectral vectors A <(0)> (k) to A <(Q)> (k). However, in reality, the microphone elements of the spherical microphone array 850 have an error derived from noise, and the influence is exerted on A <(0)> (k) to A <(Q)> (k). This effect is amplified according to T (k) and transmitted to B (k) when B (k) is calculated from A (k), as understood from (Equation 10). It becomes an error factor of sound field estimation. That is, the estimation accuracy of B (k) is reduced. [0052] Therefore, the present invention provides a sound field measurement device that estimates a sound field using a spherical wave spectrum vector B (k) whose estimation accuracy is improved by suppressing an error derived from noise of a microphone element of a spherical microphone array. The purpose is to [0053] In one aspect of the present invention, Q is an integer of 1 or more, q is an integer of 1 or more and Q or less, j n (·) is a spherical Bessel function of order n, Y nm (·) is a spherical harmonic function of order n, m , O q is a polar coordinate system whose origin is the arrangement position of the spherical microphone array of the identifier q, S q (x, k) [0054] [0055] Sound field at wave number k of point x = (r, θ, φ) in polar coordinate system O q expressed as a, a <(q)> spherical wave in polar coordinate system O q that determines μμ (k) for each wave number k By restricting the spectrum A <(q)> (k) to the expansion order of S q (x, k) as N 03-05-2019 12 [0056] [0057] S (x, k) is a spherical wave spectral vector which is determined as follows, and a polar coordinate system with O 0 as the origin of the sound field to be estimated. [0058] [0059] Sound field at wave number k of point x = (R, Θ,)) in polar coordinate system O 0 expressed as, a <(0)> nm (k) spherical wave in polar coordinate system O 0 which is determined for every wave number k By restricting the spectrum, B (k), to the expansion order of S (x, k) as N [0060] [0061] It is a sound field measuring device which calculates B (k) from A <(q)> (k) by setting it as a spherical wave spectral vector which becomes settled in て, and the arrangement position of the spherical microphone array of the origin in the polar coordinate system O 0 and the identifier q. (R q, Θ q, q q) distance is determined, and the closest microphone determining unit that determines the identifier q ′ of the spherical microphone array with the minimum distance determined, and the spherical wave of the spherical microphone array of the identifier q ′ From the spectrum a <(q ')> μμ (k), the sound pressure at the arrangement position (R q', Θ q ', ス ペ ク ト ル q') of the spherical microphone array of the identifier q 'is calculated as the first sound pressure For each of the spherical microphone arrays of identifiers 1 to Q excluding the identifier q 'using the spherical wave spectrum a <(q)> νμ (k) at the arrangement position (R q', Θ q ', q q') Sound pressure A relative power error calculation unit which calculates the relative power error of the second sound pressure relative to the first sound pressure as a relative power error, and a predetermined value indicating that the relative power error is small A spherical microphone array identifier selection unit for selecting an identifier of a spherical microphone array to be a range, and the number of spherical microphone array identifiers for which S is selected by the spherical microphone array identifier selection unit (where S ≦ Q), s is 1 or more The parameter is an integer less than or equal to Q and indicates the identifier of the S spherical microphone arrays, and the spherical wave spectral vector A <(s)> (k) of the S spherical microphone arrays is the spherical wave spectral vector B ( The mutual conversion matrix T (k) 03-05-2019 13 used to calculate k) is the arrangement position of the S spherical microphone arrays (R , Θ s, Φ s), and the spherical wave spectral vector B (k (k)) from the spherical wave spectral vector A <(s)> (k) and the mutual conversion matrix T (k). And an integration unit for calculating [0062] According to the present invention, when calculating the spherical wave spectral vector B (k), the sound field measurement accuracy can be obtained by using only the spherical wave spectrum of the spherical microphone array with a small error due to the noise of the microphone element of the spherical microphone array. That is, it is possible to improve the estimation accuracy of B (k). [0063] FIG. 6 is a block diagram showing the configuration of a sound field measurement device 800 of Non-Patent Document 1. 11 is a flowchart showing the operation of the sound field measurement device 800 of NonPatent Document 1. FIG. 10 is a block diagram showing the configuration of a sound field measurement device 900 of Non-Patent Document 2. 10 is a flowchart showing the operation of the sound field measurement device 900 of NonPatent Document 2. FIG. 1 is a block diagram showing the configuration of a sound field measurement apparatus 100 according to a first embodiment. 6 is a flowchart showing the operation of the sound field measurement apparatus 100 according to the first embodiment. FIG. 2 is a block diagram showing the configuration of a spherical microphone array selection 03-05-2019 14 unit 140 according to the first embodiment. 6 is a flowchart showing the operation of the spherical microphone array selection unit 140 according to the first embodiment. 15 is a detailed flowchart of step S142 which is a part of the operation of the spherical microphone array selection unit 140 according to the first embodiment. [0064] Hereinafter, embodiments of the present invention will be described in detail. Note that components having the same function will be assigned the same reference numerals and redundant description will be omitted. Also in the embodiment of the present invention, as in the method described in Non-Patent Document 1 or the method described in Non-Patent Document 2, the one that measures the sound field generated by the sound source located outside the measurement area, Handle internal issues. [0065] Hereinafter, the sound field measurement apparatus 100 according to the first embodiment will be described with reference to FIGS. 5 to 6. FIG. 5 is a block diagram showing the configuration of the sound field measurement apparatus 100 according to the first embodiment. FIG. 6 is a flowchart showing the operation of the sound field measurement apparatus 100 according to the first embodiment. 03-05-2019 15 As shown in FIG. 5, the sound field measurement apparatus 100 according to the first embodiment includes a short time Fourier transform unit 810, a spherical wave spectrum calculation unit 820, a position measurement unit 910, a T calculation unit 920, and a selective integration unit 130. Including. Further, the selection integration unit 130 includes a spherical microphone array selection unit 140 and an integration unit 930. A spherical microphone array 850 and an omnidirectional microphone 180 for recording the sound field are respectively outside the sound field measurement device 900. There are Q spherical microphone arrays 850, and an identifier q is given to identify each of them (Q is an integer of 1 or more, 1 ≦ q ≦ Q). Similarly, it is assumed that there are G omnidirectional microphones 180 and identifiers g are added to identify them (G is an integer of 1 or more, 1 ≦ g ≦ G). There is also a short time Fourier transform unit 810 and a spherical wave spectrum calculation unit 820 in a form corresponding to the spherical microphone array 850. Similarly, there is a short time Fourier transform unit 810 corresponding to the omnidirectional microphone 180. [0066] Let O 0 be a coordinate system whose origin is the center of the sound field to be estimated. Further, a coordinate system having an arrangement position of the spherical microphone array 850 of the identifier q (the center of the spherical microphone array 850 of the identifier q) as an origin is set to O q. The postures of the respective coordinate systems, that is, the directions of the xyz axes coincide with each other, and can be superimposed only by translational movement. Also, polar coordinates are used for all coordinate systems. This point is the same as the method described in Non-Patent Document 2. [0067] Similarly to the method described in Non-Patent Document 2, the sound field measurement apparatus 100 according to the first embodiment uses the center of the sound field to be estimated as the origin from the collected sound signal recorded using Q spherical microphone arrays 850. The spherical wave spectral vector B (k) in the coordinate system O.sub.0 is determined, but differs in that only the spherical wave spectral vector of the spherical microphone array 850 satisfying the predetermined condition is used to calculate B (k). [0068] The position measurement unit 910 measures the positions of the Q spherical microphone arrays 03-05-2019 16 850 and the G omnidirectional microphones 180 arranged in the space in the coordinate system O 0 (S 910). As described above, for example, a method of estimating the position from a plurality of camera images based on the principle of triangulation may be used. The arrangement position of the spherical microphone array 850 of the identifier q, that is, polar coordinates in the coordinate system O 0 of the origin of the coordinate system O q is (R q, Θ q, q q) (1 ≦ q ≦ Q). Let polar coordinates in the coordinate system O 0 of the arrangement position (center) of the omnidirectional microphone 180 of the identifier g be (R g, Θ g, g g) (1 ≦ g ≦ G). [0069] The spherical microphone array selection unit 140 detects the arrangement position (R q, Θ q, q q) of the spherical microphone array 850 of the identifier q and the arrangement position (R g, Θ g, g g) of the identifier g. The spherical microphone array 850 used to calculate the mutual conversion matrix T (k) is selected (S140) using (1 ≦ q ≦ Q, 1 ≦ g ≦ G). The selected spherical microphone array 850 is identified using an identifier. The process of S140 will be described in detail later. [0070] The T calculation unit 920 calculates a spherical wave spectral vector A <(s)> (k) (where k is a value) calculated from a collected sound signal recorded using the selected S (where S Q Q) spherical microphone arrays 850. , S is an integer of 1 or more and Q or less and is a parameter indicating the identifier of the selected S spherical microphone arrays, and the mutual conversion matrix T (s) used to calculate the spherical wave spectral vector B (k) k) is calculated using polar coordinates (R s, s s, s s) in the coordinate system O 0 of the origin of the coordinate system O s (S 920). The spherical wave spectral vector A <(s)> (k) is obtained from the spherical wave spectrum in the polar coordinate display in the coordinate system O s, and the spherical wave spectrum is calculated by the method described in Non-Patent Document 1 do it. The integration unit 930 calculates a spherical wave spectral vector B (k) from the spherical wave spectral vector A <(s)> (k) and the mutual conversion matrix T (k) (S930). [0071] 03-05-2019 17 The spherical microphone array selection unit 140 will be described below with reference to FIGS. 7 to 9. FIG. 7 is a block diagram showing the configuration of the spherical microphone array selection unit 140. As shown in FIG. FIG. 8 is a flowchart showing the operation of the spherical microphone array selection unit 140. FIG. 9 is a diagram showing a detailed processing flow of S142 which is a part of the operation of the spherical microphone array selection unit 140 shown in FIG. As shown in FIG. 7, the spherical microphone array selection unit 140 includes a closest microphone determination unit 141, a relative power error calculation unit 142, and a spherical microphone array identifier selection unit 143. [0072] The closest microphone determination unit 141 determines the arrangement position (R q, Θ q, q q) of the spherical microphone array 850 of the identifier q and the arrangement position (R g, Θ g, g g) of the omnidirectional microphone 180 of the identifier g. (1 ≦ q ≦ Q, 1 ≦ g ≦ G) to determine the spherical microphone array 850 or omnidirectional microphone 180 closest to the origin of the coordinate system O 0 which is the center of the sound field to be estimated S141). Specifically, the identifier q or g of the smallest one of R q and R g (1 ≦ q ≦ Q, 1 ≦ g ≦ G) may be selected. [0073] The relative power error calculation unit 142 calculates the relative power error by a method according to whether the microphone closest to the origin of the coordinate system O 0 is the spherical microphone array 850 or the omnidirectional microphone 180 (S 142). If the closest one is the spherical microphone array 850 (the identifier is assumed to be q ') (that is, if it is YES in S1421), the arrangement position of the spherical microphone array 850 of the identifier q' (R q ', Θ q) The sound pressure at ', q q') is calculated (S 1422 a). Let this be the first sound pressure. The first sound pressure can be calculated as spherical wave spectrum a <(q ')> 00 (k). Next, for the spherical microphone array 850 of the identifiers 1 to Q excluding the identifier q ′, using the spherical wave spectrum a <(q)> nm (k), the arrangement position of the spherical microphone array 850 of the identifier q ′ (R The sound pressure at q ′, Θ q ′, Φ q ′) is estimated and calculated as the second sound pressure (S1423a). In the second sound pressure a ^ <(q ')> q (k), polar coordinates of the arrangement position of the spherical microphone array 850 of the identifier q' in the coordinate system O q are calculated, and It can be calculated by substitution. Finally, the relative power error of a ^ <(q ')> q (k) with respect to a <(q')> 00 (k) is calculated (S1424a). That is, (Q-1) pieces of relative power errors are calculated. The relative 03-05-2019 18 power error can be calculated as | a <(q ')> 00 (k)-a ^ <(q')> q (k) / / a <(q ')> 00 (k) |. [0074] On the other hand, if the closest one is the omnidirectional microphone 180 (the identifier is g ') (that is, NO in S1421), the arrangement position of the omnidirectional microphone 180 of the identifier g' (R g The sound pressure at ', Θ g', g g ') is calculated (S 1422 b). Let this be the third sound pressure. The third sound pressure p g ′ (k) is obtained as the frequency f = kc / 2π from the frequency domain signal obtained by subjecting the collected sound signal recorded by the omnidirectional microphone 180 having the identifier g ′ to short time Fourier transformation It can be calculated. Next, for the spherical microphone array 850 of the identifiers 1 to Q, using the spherical wave spectrum a <(q)> nm (k), the arrangement position (R g ′, Θ g of the omnidirectional microphone 180 of the identifier g ′ The sound pressure at ', g g') is estimated and calculated as a fourth sound pressure (S1423 b). The fourth sound pressure a ^ <(g ')> q (k) can be calculated by the same method as the method in S1423a. Finally, the relative power error of a ^ <(g ')> q (k) with respect to pg' (k) is calculated (S1424b). That is, Q relative power errors are calculated. The relative power error can be calculated by the same method as the method in S1424a. [0075] The processing in the short time Fourier transform unit 810 for calculating the frequency domain signal by the short time Fourier transform from the sound collection signal recorded by the omnidirectional microphone 180 is unnecessary when the closest one is the spherical microphone array 850. The process may be delayed until the determination process of S1421 is performed. [0076] The spherical microphone array identifier selection unit 143 determines the spherical microphone array 850 that is within a predetermined range indicating that the relative power error calculated in S142 is small as a spherical microphone array used for calculating the mutual conversion matrix T (k) (S143). ). The predetermined range may be, for example, equal to or less than a preset threshold, or may be smaller than the preset threshold. Further, the threshold may be 0.2 to 0.3. 03-05-2019 19 [0077] Note that the arrangement positions (R q, Θ q,) q) and (R g, Θ g, g g) (1 Θ q Φ Q, 1 g g G G) of the spherical microphone array 850 and the omnidirectional microphone 180 are used. If known in advance, the sound field measurement apparatus 100 can be configured without the position measurement unit 910. [0078] Also, the sound field measurement apparatus 100 can be configured not to have the omnidirectional microphone 180. In this case, the processing flow of S142 shown in FIG. 9 is such that only the processing of S1422a, S1423a, and S1424a is executed because the determination processing of S1421 is unnecessary. [0079] From the spherical wave spectral vector A <(s)> (k) and the mutual conversion matrix T (k), the spherical wave spectral vector B (k) is calculated using (Equation 10). The estimation of the sound field using B (k) calculated in this manner is basically extrapolation, and the error of the extrapolation is influenced by the relative positional relationship and the like of the spherical microphone array. The present invention checks the validity of this extrapolation and calculates B (k) excluding an invalid spherical microphone array, that is, one whose relative power error is not within a predetermined range. As a result, it becomes possible to finally calculate B (k) better. <Supplement> The device according to the present invention is, for example, an input unit to which a keyboard can be connected, an output unit to which a liquid crystal display etc can be connected as a single hardware entity, a communication device capable of communicating outside the hardware entity Communication unit to which the communication cable can be connected, CPU (Central Processing Unit, may be provided with a cache memory, a register, etc.), RAM or ROM which is a memory, external storage device which is a hard disk, and input / output units thereof , A communication unit, a CPU, a RAM, a ROM, and a bus connected so as to enable exchange of data between external storage devices. If necessary, the hardware entity may be provided with a device (drive) capable of reading and writing a recording medium such as a CDROM. Examples of physical entities provided with such hardware resources include general 03-05-2019 20 purpose computers. [0080] The external storage device of the hardware entity stores a program necessary for realizing the above-mentioned function, data required for processing the program, and the like (not limited to the external storage device, for example, the program is read) It may be stored in the ROM which is a dedicated storage device). In addition, data and the like obtained by the processing of these programs are appropriately stored in a RAM, an external storage device, and the like. [0081] In the hardware entity, each program stored in the external storage device (or ROM etc.) and data necessary for processing of each program are read into the memory as necessary, and interpreted and processed appropriately by the CPU . As a result, the CPU realizes predetermined functions (each component requirement expressed as the above-mentioned,... [0082] The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. Further, the processes described in the above embodiment may be performed not only in chronological order according to the order of description but also may be performed in parallel or individually depending on the processing capability of the apparatus executing the process or the necessity. . [0083] As described above, when the processing function in the hardware entity (the apparatus of the present invention) described in the above embodiment is implemented by a computer, the processing content of the function that the hardware entity should have is described by a program. Then, by executing this program on a computer, the processing function of the hardware entity is realized on the computer. 03-05-2019 21 [0084] The program describing the processing content can be recorded in a computer readable recording medium. As the computer readable recording medium, any medium such as a magnetic recording device, an optical disc, a magneto-optical recording medium, a semiconductor memory, etc. may be used. Specifically, for example, as a magnetic recording device, a hard disk device, a flexible disk, a magnetic tape or the like as an optical disk, a DVD (Digital Versatile Disc), a DVDRAM (Random Access Memory), a CD-ROM (Compact Disc Read Only) Memory), CD-R (Recordable) / RW (Rewritable), etc. as magneto-optical recording medium, MO (Magneto-Optical disc) etc., as semiconductor memory EEP-ROM (Electronically Erasable and Programmable Only Read Memory) etc. Can be used. [0085] Further, this program is distributed, for example, by selling, transferring, lending, etc. a portable recording medium such as a DVD, a CD-ROM or the like in which the program is recorded. Furthermore, this program may be stored in a storage device of a server computer, and the program may be distributed by transferring the program from the server computer to another computer via a network. [0086] For example, a computer that executes such a program first temporarily stores a program recorded on a portable recording medium or a program transferred from a server computer in its own storage device. Then, at the time of execution of the process, the computer reads the program stored in its own recording medium and executes the process according to the read program. Further, as another execution form of this program, the computer may read the program directly from the portable recording medium and execute processing according to the program, and further, the program is transferred from the server computer to this computer Each time, processing according to the received program may be executed sequentially. In addition, a configuration in which the above-described processing is executed by a so-called ASP (Application Service Provider) type service that realizes processing functions only by executing instructions and acquiring results from the server computer without transferring the program to the computer It may be Note that the program in the present embodiment includes information provided for processing by a computer that conforms to the program (such as data that is not a 03-05-2019 22 direct command to the computer but has a property that defines the processing of the computer). [0087] Further, in this embodiment, the hardware entity is configured by executing a predetermined program on a computer, but at least a part of the processing content may be realized as hardware. 03-05-2019 23

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