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 JP2003075245 [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for correcting a sound wave selectively picked up from a moving sound source using a microphone array. [0002] 2. Description of the Related Art A sound collecting device is known which obtains directivity by weighted averaging of signal outputs of sound waves collected by microphones using a microphone array. In the conventional sound pickup apparatus, a plane wave was assumed as the incident wave. Assuming that the distance | x | from the sound source to the measurement position is 20 m, the size l of the sound source is sufficiently small, and the wavelength of the sound wave is λ, acoustic far-field conditions | x | >> λ and the acoustic compact condition λ >> l are satisfied. Therefore, it relies on the fact that the incident wave to the microphone can be regarded as a plane wave. Such a sound collecting device is described, for example, in Japanese Patent No. 1134369. Further, a correction method in the case where the sound source is positioned in a direction other than the direction perpendicular to the axis of the microphone array is disclosed in JP-A-5-91588. [0003] 04-05-2019 1 However, in the case of low-frequency sound (where λ is relatively large), the acoustic compact condition is considered to hold, but the acoustic far-field condition does not hold. . Therefore, when collecting low frequency sound, it can not be considered as a plane wave. Also, even when the distance from the sound source to the measurement position is small compared to the frequency of the sound wave to be collected, the acoustic far-field condition does not hold similarly, so it can not be regarded as a plane wave as well. Under such conditions, when a sound wave is measured as a plane wave, there is a problem that the directivity characteristic is degraded. The present invention is a device having an appropriate directivity characteristic even when the sound wave can not be considered as a plane wave, such as when the wavelength is relatively long or when the distance between the sound source and the measurement position is relatively short. Intended to provide. [0004] SUMMARY OF THE INVENTION A sound measurement and analysis apparatus for obtaining directivity by superposing outputs of microphones of a microphone array in which a plurality of microphones are arranged on a substantially straight line, which comprises: A band pass filter for filtering each output with a filter having predetermined characteristics including a center frequency to be acquired, a sound source as a nonpolarity monopole point sound source, and a sound wave incident on a microphone as a spherical wave Under the assumption that the correction means for correcting the amplitude and phase of the filtered output based on the relative position of each of the microphones to the sound source, and the superimposed waveform by superimposing the waveform corrected by the correction means And waveform weighting means for obtaining .mu. [0005] In a preferred embodiment, of the outputs from the microphone, further, at equal intervals along a straight line, the (n) th such interval is 1⁄2 of the wavelength λ c of the sound wave of the center frequency. No. 0 No.... An acquiring means for acquiring an output from the (n + 1) th (2n + 1) microphones, wherein the correcting means relates to each of the outputs acquired by the acquiring means 1) The amplitude of the sound pressure pj observed by the j-th microphone is multiplied by qj, and (2) the acquisition time of the sound pressure pj observed by the j-th microphone is s (qj-1) / Delay by c0 (where q j = (1 + (j λ c / 2 s) 2) 1/2, s is the position of the 0th microphone and the 0th microphone on a straight line along the microphone array Extend from the position of The distance between the intersection of the straight line and parallel to the straight line passing through the line and the sound source, c0 is the sound velocity) manner, is configured so as to correct the amplitude and phase. 04-05-2019 2 In the present specification, “acquisition time” does not mean the time for actually acquiring the emitted sound wave, but changes the time axis in the data as if the acquisition time is delayed, for example. It means that. [0006] In the above embodiment, the sound wave of the microphone is acquired such that the distance between the microphones to be used is a half wavelength of the sound wave of the center frequency to be analyzed. According to the above embodiment, when the sound source is fixed, it is possible to obtain a good superimposed waveform of the directional characteristics. [0007] In another preferred embodiment of the present invention, the output from the microphones is equally spaced on a straight line such that the interval is 1⁄2 of the wavelength λ c of the sound wave of the center frequency. n) No. 0: No. 0: obtaining means for obtaining an output from (n + 1) th (2n + 1) microphones, the correction means relates to each of the outputs obtained by the obtaining means , (1) The amplitude of the sound pressure pj observed by the j-th microphone is multiplied by qj, and (2) the acquisition time of the sound pressure pj observed by the j-th microphone is s (qj-1 ) / C 0 (where q j is the equation shown in Equation 5 below, s is the position of the 0th microphone and the 0th microphone on a straight line along the microphone array) Hanging from the position The distance between the line and the point of intersection of the straight line passing through the sound source and the straight line parallel to it, c0 is the speed of sound, U is the moving speed of the sound source, M = U / c0), so as to correct its amplitude and phase. It is configured. According to this embodiment, when the sound source moves, by installing the microphone array so as to be parallel to the moving direction, it is possible to obtain a superimposed waveform with a good directional characteristic. . [0008] In another preferred embodiment, of the outputs from the microphones, the intervals are a half of the wavelength λc of the sound wave of the center frequency at equal intervals on a straight line. (-N) No.... No. 0... An acquisition means for acquiring an output from (n) th (2n + 1) microphones, wherein the correction means is an output of the output means acquired by the 04-05-2019 3 acquisition means For each, (1) the amplitude of the sound pressure pj observed by the j-th microphone is multiplied by qj (1-M cos Θ oj) 2 and (2) acquisition of the sound pressure pj observed by the j-th microphone The time is delayed by s (qj-1) / c0 and its frequency is multiplied by (1-M cos Θ oj), where q j is a formula shown in the following equation 6, and s is the 0th microphone. Position and the The distance between the vertical line extending from the position of the 0th microphone and the straight line parallel to the straight line passing through the sound source, c0 is the speed of sound, and U is the movement of the sound source The velocity, M = U / c0, Θoj, where t = 0 is the time when the sound source passes the perpendicular line of the straight line extending from the 0th microphone, t = s from the time when the sound wave is emitted from the sound source To correct the amplitude and phase so that the direction vector when looking at the jth microphone from the position of the sound source at time t when / c0 has elapsed and the direction vector that coincides with the moving direction of the sound source It is configured. ## EQU6 ## In this embodiment, it is possible to obtain superimposed waveforms with good directional characteristics, taking into consideration the Doppler coefficient. Furthermore, the object of the present invention is also achieved by a sonometry analysis program which causes a computer to function as each means described above. [0009] BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram showing a schematic configuration of a sonic measurement analysis system according to the present invention. As shown in FIG. 1, in this sonic measurement analysis system, (2n + 1) microphones 14-(-n), 14- (n-1), ..., 14-0, ... in the axial direction. , 14-n are connected to the data recorder 16. The microphone array 12 is configured by the (2n + 1) microphones. In the present embodiment, a so-called micro-pressure gauge is used as a microphone so that low-frequency sound can be measured. [0010] Further, in the present embodiment, signals collected by (2n + 1) microphones are applied to the data recorder 16, and signals from the respective microphones 14 are accumulated in the data recorder. Also, a processing device 18 is connected to the data recorder 16. [0011] 04-05-2019 4 The processing unit 18 receives an acoustic signal collected by each microphone 14 from the data recorder 16 and digitizes the acoustic signal, and the A / D converter 20 and the data subjected to the calibration process. And a band pass filter (BPF) 22 which executes band pass filter processing, a correction processing unit 24 which executes necessary correction processing considering that the given waveform is a spherical wave, and And a composite waveform generation unit 26 for converting the superimposed waveform into a physical quantity indicating power. The processing unit 18 further includes an input unit 28 such as a keyboard and a mouse, a display unit 30 such as a CRT, and a processing control unit 32 for controlling various components in the processing unit and processing thereof. [0012] The processor 18 according to the present embodiment can be realized by a personal computer. By installing the processing program stored in the CD-ROM in the personal computer, it is possible to realize the function. [0013] [Principle of the Invention] Before describing the processing in the acoustic measurement and analysis system configured as described above, the principle of the present invention will be described below. First, assuming that the incident wave is a plane wave, as shown in FIG. 2, the (n) th, the (-n + 1) th,..., The 0th (zero) th,. The (2n + 1) microphones of are disposed at equal intervals d on the axis 200, and it is considered that sound waves are incident from a direction deviated from the direction perpendicular to the axis 200 by an angle θ. Here, the microphone distance d and the wavelength λc of the incident wave are set so as to satisfy the following relationship. In FIG. 2, the distance between the wavefronts 201 and 202 corresponds to the wavelength λ c of the incident wave. d = λc / 2 (1.1) [0014] Since the incident wave is assumed to be a plane wave, the sound pressure pj observed by the jth microphone (see reference numeral 201) is expressed by the following equation. Here, A, ω and ψ j respectively indicate the amplitude of the incident wave, the angular frequency, and the 04-05-2019 5 phase difference at the j-th microphone 14-j. Assuming that the phase difference in the 0th microphone 14-0 is "0 (zero)", the phase difference of the jth microphone is given by ψ j = 0 0 j (λ c / 2) sin θ (1.3). However, it is κ0 = ω / c0 (1.4). However, when ωc is an angular frequency corresponding to λc and the dimensionless angular frequency Ω is defined as Ω = ω / ωc (1.5), the above equation (1.4) becomes κ0 = κcΩ (1.6) Equation (1.2) can be modified as follows using equations (1.3) and (1.6). [Equation 8] [0015] Assuming that the weight of the j-th microphone is w j, a weighted superposition waveform P (θ, Ω) in which the outputs of the respective microphones are superposed can be expressed as follows. [Equation 9] [0016] Taking the square of this absolute value, the following equation is obtained, and the value of equation (1.9) when θ = 0 is: | P (0, Ω) | 2 = A 2 (1.10) ). Thereby, the directivity characteristic K2 (θ, Ω) of the weighted superimposed waveform can be expressed as follows. [Equation 11] [0017] The value obtained by multiplying the common logarithm of the above equation (1.11) by 10 provides the sensitivity characteristic in decibel display. In FIG. 3, to each microphone of the microphone array consisting of five microphones, microphone weights of predetermined weights (for example, both ends (numbers (-2) and 2): weight of 0.125, remainder (number -1) is a graph calculated by setting the weight of the microphone of No. 0, No. 0 and No. 1): 0.25). In FIG. 3, the center frequency corresponds to equation (1.11). [0018] [Fixed Point Sound Source] On the other hand, in the present invention, a spherical wave is assumed as the incident sound wave. First, as shown in FIG. 4, a description will be added on the assumption that the sound source is a monopole point sound source having no directivity. 04-05-2019 6 Assuming a spherical wave, the sound pressure pj observed by the j-th microphone in FIG. 4 can be expressed as follows. Where x j and y are the position of the observation point, ie, the j-th microphone, and the position of the sound source S, respectively, and are given as follows. xj = (j (λc / 2), 0,0) (2.2) y = (s * tan θ, s, 0) (2.3) where s is the position of the 0th microphone, The distance between the vertical line extending from the position of the zeroth microphone and the intersection point of the sound source S and a line parallel to the axis of the microphone, and θ is the position of the normal line and the position of the zeroth microphone It is an angle formed by a straight line extending to the sound source S. [0019] The distance | xj−y | between the observation point and the sound source can be expressed by the following equation (13) using the equations (2.1) and (2.2). Here, when equation (2.4) is transformed, | xj−y | becomes as follows. Using equation (2.5), equation (2.1) is expressed as follows: [Equation 15] [0020] Therefore, a weighted superposition waveform P (θ, Ω) in which the outputs pj of the respective microphones are superposed is expressed as follows. The square of the absolute value of P (θ, Ω) expressed by equation (2.9) is: ## EQU17 ## and when θ = 0 in equation (2.10) above, α j Since (0) = 1, the following equation is obtained. Therefore, the directivity characteristic K2 (θ, Ω) of the weighted superimposed waveform can be expressed as follows. [Equation 19] [0021] FIG. 5 and FIG. 6 are graphs showing directivity specification Koct2 of the octave band calculated based on the directivity characteristic shown by the above equation (2.12). In FIGS. 5 (a) and 5 (b) and FIGS. 6 (a) and 6 (b), "s = ** m" described at the lower right of the graph indicates the distance from the sound source. It will be understood from these graphs that as the distance s from the sound source becomes shorter, and as the frequency of the sound source becomes lower, the directivity characteristic of the microphone array gets worse. [0022] 04-05-2019 7 In the case of a plane wave, when the incident angle of the sound wave is 0 °, the amplitudes (distance attenuation) and phases of the sound waves measured by the respective microphones are aligned. On the other hand, in the case of a spherical wave, as shown in FIG. 7, since the wavefront 702 is spherical (circular in FIG. 7) even if the incident angle is 0.degree. Because the phase is different, the directivity characteristic is degraded. Therefore, for example, when the incident angle is 0 °, that is, when the sound source is located in front, it is possible to suppress the deterioration of the directional characteristic by correcting so that the amplitude and phase in each microphone are aligned. In the present specification, this is referred to as "spherical wave correction". [0023] First, consider the amount of correction to the amplitude. In FIG. 7, assuming that the distance between the 0th microphone and the sound source S is s, the distance R0j between the jth microphone and the sound source S can be expressed by the following equation (3.1) . Therefore, the correction amount q j for making the amplitudes of the sound waves arriving at the 0th microphone and the sound waves arriving at the jth microphone can be determined as follows. [Equation 21] [0024] Next, consider the phase correction amount. The distance R0j between the j-th microphone and the sound source S and the difference ΔRj between the zero-th microphone and the sound source S can be expressed by the following equation. Therefore, when the sound wave having the same phase as the sound wave reaching the 0th microphone reaches the jth microphone, assuming that the sound velocity is c0, Δt = (s / c0) (qj-1) The time is delayed by (3.4). Therefore, in order to align the phases of the sound waves reaching the microphones, the acquisition time of the sound pressure of the j-th microphone may be delayed by Δt. [0025] Therefore, in the present invention, (1) the amplitude of the sound pressure pj observed by the jth microphone is multiplied by qj, and (2) the sound pressure pj observed by the j-th microphone 04-05-2019 8 The acquisition time is delayed by s (qj-1) / c0. When corrected as described above in equation (2.1), the corrected sound pressure pj 'is as follows. [Equation 23] [0026] Substituting the equations (1.6) and (2.5) into the equation (3.5) gives the equation (3.6). Further, a weighted superimposed waveform P ′ (θ, Ω) obtained by superposing the outputs of the microphones based on Equation (3.6) is as shown in Equation (3.7). The square of the absolute value of the above equation (3.7) can be obtained as in equation (3.8). In the equation (3.8), the value of θ = 0 is αj (0) = 1 and Σ (j = −n, −n + 1,..., 0,... N) wj = 1 Therefore, | P ′ (0, Ω) | 2 = A2 / s2 (3.9). [0027] Thus, the directivity characteristic (K '(.theta., .OMEGA.)) 2 of the weighted superposition waveform after the spherical wave correction can be obtained as follows. [Equation 26] [0028] FIGS. 8 and 9 are graphs showing directivity characteristics Koct2 of an octave band calculated based on the directivity characteristics shown in equation (3.10). In FIGS. 8A and 8B and FIGS. 9A and 9B, “s = ** m” described at the lower right of the graph indicates the distance from the sound source. By comparing FIGS. 8 and 9 with FIGS. 5 and 6, it can be understood that the spherical wave correction improves the directivity of the microphone array. [0029] Moving Point Sound Source Furthermore, in the present invention, spherical wave correction can be performed in consideration of movement of the point sound source. This principle will be described below. Also for the moving point sound source, (1) the amplitude of the sound pressure pj observed by the j-th microphone is multiplied by qj and (2) the acquisition time of the sound pressure pj observed by the j-th microphone It is based on delaying by s (qj-1) / c0. However, for the amplitude qj, the following equation is used. [Equation 27] 04-05-2019 9 [0030] Here, M is the Mach number of the sound source S. Assuming that the moving speed of the sound source S is U and the sound speed is c0, M is defined as M = U / c0. When the sound source S moves, the angle between the vector connecting the jth microphone and the sound source and the vector in the movement direction of the sound source changes. In equation (4.2), Θ j is a direction vector (see symbol 1001 in FIG. 10) when looking at the observation point of the j-th microphone from the sound source S at time t and a direction vector (in the direction of movement of the sound source The angle with respect to the reference numeral 1002 in FIG. 10 is shown (see FIG. 10). When spherical wave correction is performed on the sound pressure pj (t) of the moving sound source S represented by equation (4.2), the corrected sound pressure pj ′ (t) is represented as equation (4.3) be able to. [Equation 28] [0031] By rearranging the equation (4.3), the corrected sound pressure pj '(t) can be expressed as follows. Therefore, the weighted superposition waveform P '(t, Ω) in which the outputs of the respective microphones are superposed can be expressed as follows. [Equation 30] [0032] The square of the absolute value of the weighted superimposed waveform is expressed by equation (4.8). Here, in equation 4.8, when the value of t = s / c0 is expressed as cos Θ j when cos Θ j at t = s / c 0, α j (s / c 0) = 1, so It becomes like 4.9). [Equation 31] [0033] Thus, the directivity (K '(t, Ω)) 2 of the weighted superposition waveform can be expressed as follows. Even when the moving point sound source moves, basically (1) the amplitude of the sound pressure pj observed by the j-th microphone is multiplied by q j, and (2) the j-th The correction is realized by delaying the acquisition time of the sound pressure pj observed by the microphone of the above by s (qj-1) / c0. However, qj takes into consideration the Mach number 04-05-2019 10 as shown in equation (4.1). FIG. 11 is a graph showing the directivity characteristics of the octave band calculated based on the directivity characteristics shown in equation (4.10). FIG. 11A shows the characteristics at center frequencies of 31.5 Hz, 16 Hz and 8 Hz when the distance s from the sound source is 32.088 m and the velocity of the moving point sound source is set to 100 km. [0034] In FIGS. 11 (b) and 11 (c), the distance from the sound source and the center frequency are the same as in FIG. 11 (a), while the speed of the point sound source is 300 km and 500 km, respectively. It can be seen from FIG. 11 that relatively good characteristics are obtained even if the speed of the point sound source is high. [0035] [Description of Specific Operation of System] In the present embodiment, the following processing is performed using the above principle. Here, sound waves emitted from a sound source moving on a substantially straight line are collected at a predetermined speed. FIG. 12 is a diagram showing the structure of the microphone array used in the present embodiment. Here, a microphone array is arranged to pick up low frequencies emitted from a train traveling on the track. As shown in FIG. 12, the microphone array 1200 is arranged such that its axis is parallel to the line 1210. In the present embodiment, nine microphones 14-1 to 14-9 are arranged in the microphone array 1200. Note that this microphone array is not referred to as the n-th microphone, but is referred to as a 1-ch microphone, a 2-ch microphone,. [0036] In this embodiment, in order to pick up sound waves of 31.5 Hz, 16 Hz and 8 Hz, the microphone spacing is d1 = 5.397 m, 2 ch, 3 ch between 3 ch to 7 ch microphones. Between the 5ch, 7ch and 8ch microphones, d2 = 10.625m, 1ch, 2ch, 5ch, 8ch and 9ch microphones, d3 = 21.250m. These intervals are equal to the half wavelengths λc / 2 of the 31.5 Hz, 16 Hz and 8 Hz sound waves, respectively. In addition, the distance D between the movement vector of the sound source (see reference numeral 1210) and each microphone is 32.088. [0037] 04-05-2019 11 As shown in FIG. 13 which is a flow chart showing the processing procedure, from the train traveling at about 230 km / hr and the train traveling at about 270-280 km / hr using the microphone array 1200 arranged as described above. The sound waves emitted and collected by the microphones 14-1 to 14-9 are recorded in the data recorder 16 (step 1301). [0038] Thereafter, the processing control unit 32 of the processing unit 18 issues an instruction or the like to each component in the processing unit 18 in accordance with an analysis program stored in a memory or a hard disk drive (not shown). Thus, analysis processing is performed. The processing unit 18 A / D converts the signal acquired by each microphone 14 recorded in the data recorder 16 and temporarily stores it, for example, in a memory (not shown) in the processing unit 18 (step 1302). ). At the time of analysis, the processing unit 18 selects a data set based on a signal acquired from a predetermined microphone according to the frequency to be analyzed (step 1303). For example, when the center frequency is 31.5 Hz, a data set based on signals acquired from 3 to 7 ch microphones is selected. [0039] Next, the data making up the selected data set is filtered by the BPF 22 under the characteristics determined by the center frequency (step 1304). Next, spherical wave correction is performed on each data in the correction processing unit 24 (step 1305). As described above, in the present embodiment, (1) the amplitude of the sound pressure pj observed by the j-th microphone is multiplied by qj and (2) the sound pressure observed by the j-th microphone The acquisition time of pj is delayed by s (qj-1) / c0. Where s is the distance between the position of the zeroth microphone and the point of intersection of a vertical line extending from the position of the zeroth microphone and a line parallel to the axis of the microphone passing through the sound source S, c0 Is the speed of sound. [0040] In the present embodiment, for example, spherical wave correction is possible for each of the fixed point sound source and the moving point sound source, and the operator sets the operation 04-05-2019 12 mode to perform spherical wave correction under any of the modes. It is desirable to configure it to perform Here, in the operation mode of the fixed point sound source, q j based on equation (3.2) is used. In addition, in the operation mode of the moving point sound source, qj based on the equation (4.1) may be used. [0041] Data based on the sound waves acquired from the microphones corrected for spherical waves in this way is given to the waveform generation unit 26. After superimposing the respective data (step 1306), the waveform generation unit 26 evaluates the superimposed waveform according to the following equation (5.1) (here, referred to as "average pointing power waveform") (Step 1307). Where T is a time constant, ρ 0 = 2 × 10 −5 Pa. This takes into consideration that the acquired raw pressure waveform is complicated and difficult to use. The data generated in this manner is stored, for example, in a database (not shown) or displayed on the screen of the display device 30 (step 1308). The average pointing power waveform obtained in step 1308 and the pointing power waveform obtained by squaring after superposition obtained in the previous step are compared or further processed to be analyzed. It can be [0042] According to the present embodiment, the amplitude and phase of the sound wave from the point sound source are corrected in consideration of reaching the microphones arranged on the array as spherical waves. Therefore, it is possible to obtain a superimposed waveform with a good directional characteristic. [0043] FIGS. 14 (a) to 14 (c) show examples of the directivity power waveform without the spherical wave correction according to this embodiment and the directivity power waveform after the spherical wave correction. In FIGS. 14 (a) to 14 (c), the broken line indicates the waveform before the spherical wave correction, and the solid line indicates the waveform after the spherical wave correction. These are obtained by obtaining a pointing power waveform based on a sound wave acquired when a vehicle traveling at a speed of 272 km / hour passes. Fig. 14 (a) shows a power waveform at 31.5 Hz, Fig. 14 (b) at 16 Hz, and Fig. 14 (c) at 8 Hz. It can be understood that the peak value is larger in the spherical wave-corrected one (see the solid line) by comparing the 04-05-2019 13 peak values when the head portion of the train and the portion where the cover of the pantograph is located pass. The present invention is not limited to the above embodiment, and various modifications are possible within the scope of the invention described in the claims, and they are also included in the scope of the present invention. It goes without saying that [0044] For example, in the above embodiment, in the case of the moving point sound source, the amplitude and phase are corrected without considering the Doppler effect. However, correction may be performed in consideration of the Doppler effect. In this case, (1) the amplitude of the sound pressure pj observed by the j-th microphone is multiplied by qj (1-M cos Θ 0 j) 2 and (2) the sound pressure pj observed by the j-th microphone The acquisition time of s may be delayed by s (qj-1) / c0 and its frequency may be multiplied by (1-M cos Θ 0 j). However, here, Θoj, Θoj is a time when the sound source passes through a straight perpendicular line extending from the 0th microphone and the microphone array is extended from t = 0, a sound wave is emitted from the sound source The direction vector when looking at the jth microphone from the position of the sound source at time t when t = s / c 0 has elapsed from the time is the angle between the direction vector that coincides with the moving direction of the sound source. [0045] It goes without saying that the number of microphones constituting the microphone array is not limited to the above embodiment. It is also clear that the spacing of the microphones can also be changed accordingly according to the frequency of the sound waves to be measured and analyzed. [0046] Furthermore, in the above embodiment, the signal from the microphone 14 is recorded in the data recorder 16 at one end, and the signal output from the data recorder 16 is digitized by the A / D converter 20. The configuration is not limited to such a configuration, and the signal from the microphone 14 may be directly given to the A / D converter 20 without passing through a data recorder. In this case, step 1301 is omitted in FIG. 04-05-2019 14 [0047] According to the present invention, the sound wave can not be considered as a plane wave, for example, when the wavelength is relatively long or when the distance between the sound source and the measurement position is relatively short. Also, it is possible to provide a device with appropriate directional characteristics. [0048] Brief description of the drawings [0049] FIG. 1 FIG. 1 is a block diagram showing a schematic configuration of a sonic measurement analysis system according to the present invention. [0050] FIG. 2 is a view schematically showing sound waves incident on the respective microphones when a plane wave is assumed. [0051] FIG. 3 is a diagram showing an example of directivity characteristics based on superimposed waveforms using a microphone array when a plane wave is assumed. [0052] FIG. 4 is a view schematically showing sound waves incident on the microphones when the sound source is considered to be a monopole element point sound source having no directivity. [0053] FIG. 5 is a diagram showing an example of the directivity characteristic based on the superimposed waveform of the waveforms to which the correction according to the present embodiment is not applied when the spherical wave is assumed. [0054] FIG. 6 is a diagram showing an example of the directivity characteristic based on the superimposed waveform of the waveforms not subjected to the correction according to the present embodiment when the spherical wave is assumed. 04-05-2019 15 [0055] FIG. 7 is a view schematically showing a state where a spherical wave from a point sound source is incident on each microphone. [0056] FIG. 8 is a diagram showing an example of the directivity characteristic based on the superimposed waveform of the waveforms subjected to the correction according to the present embodiment when a spherical wave is assumed. [0057] FIG. 9 is a diagram showing an example of the directivity characteristic based on the superimposed waveform of the waveforms subjected to the correction according to the present embodiment when the spherical wave is assumed. [0058] FIG. 10 is a view schematically showing a state where a spherical wave from a point sound source is incident on each microphone when the point sound source moves. [0059] FIG. 11 is a diagram showing an example of the directivity characteristic based on the superimposed waveform of the waveform corrected according to the present embodiment, assuming a spherical wave radiated from the moving point sound source. [0060] FIG. 12 is a diagram showing the structure of the microphone array used in the present embodiment. [0061] FIG. 13 is a flowchart showing the processing procedure executed by the sound wave measurement and analysis system according to the present embodiment. [0062] 04-05-2019 16 FIG. 14 is a diagram showing a power waveform based on the superimposed waveform before and after the correction according to the present embodiment. [0063] Explanation of sign [0064] 12 microphone array 14 microphone 16 data recorder 18 processing device 20 A / D converter 22 BPF 24 correction processing unit 26 waveform generation unit 28 input device 30 display device 32 processing control unit 04-05-2019 17

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