JP2019035628A - Space sound analysis method and system thereof - Google Patents

Abstract

To provide a sound analysis method including a transmission path analysis between a sound source within space and an observation position, and to provide a system of the sound analysis system.SOLUTION: A sound analysis method allows a sound field formed in space to be analyzed. A sound sensor is disposed in an observation position within space, a speaker is moved along a set, virtual sound source surface and a sound particle speed of sound generated from the speaker is measured by a sound particle speed sensor disposed in front of the speaker, and a transfer function acquisition process for acquiring a transfer function between the observation position and its surrounding is included. The sound analysis system includes the sound sensor disposed in an observation position within space, the speaker disposed on a set virtual sound source surface, and the sound particle speed sensor disposed in front of the speaker, the speaker is moved along the virtual sound source surface and a sound particle speed of sound generated by the speaker is measured by the sound particle speed sensor, and the transfer function acquisition part for acquiring a transfer function between an observation position and its surrounding is included.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an acoustic analysis method and system therefor, and more particularly to an acoustic analysis method and system including an analysis of a transmission path between a sound source and an observation position in the space.

  What kind of noise (vibration sound) is felt by passengers inside automobiles, railway cars, aircraft, and other spaces, and how noise propagates in the space, and the acoustics about the space Analysis is required. As one method of such acoustic analysis, transfer path analysis (TPA) for evaluating an energy transfer path via air between a sound source and an observation position corresponding to the head of a passenger is performed. For example, the sound pressure by the air propagation path is obtained by multiplying the volume acceleration from the surface of the sound source such as a wall by a transfer function.

  For example, in Non-Patent Document 1, in the transmission path analysis for grasping the contribution degree of each noise / vibration propagation path in a vehicle from a sound source such as a railway vehicle carriage, data of the railway vehicle actually running is used. Describes the method. Using vibration acceleration sensors attached to multiple locations, observe vibration acceleration in three directions at each location, and perform analysis using a transfer function defined between the input point (sound source) and the evaluation point (observation position) ing.

  By the way, the intensity of sound waves is expressed by sound pressure and particle velocity. This sound pressure can be observed as acceleration by a microphone, but it is necessary to consider the particle velocity in order to obtain various information such as force acting on the field.

  For example, in Patent Document 1, “acoustic particles” as air particles that transmit sound instead of sound pressure are taken into consideration, and this velocity observation is performed at the observation position, and transmission from the sound source to the observation position (sound receiving side). It discloses disclosing the function. In the sound path consisting of the structure propagation path from the sound source to the observation position and the air propagation path, the structure propagation path measures the force applied to the structure support by the force sensor and acceleration sensor, and the air propagation path emits the sound source. Volume acceleration is measured by a volume acceleration sensor attached near the surface. An acoustic particle velocity sensor is arranged at the observation position to determine a particle velocity vector, and the contribution of each path from the sound source to the particle velocity vector can be analyzed by a three-dimensional vector method.

  In Non-Patent Document 2, an observation device such as a microphone is not arranged at the observation position, but conversely, a simulated sound source is arranged at the observation position and a microphone is arranged at the sound source side, and the transfer function is used. It describes the method of conducting transmission path analysis from the reciprocity of. According to the acoustic excitation method using the reciprocity theorem, a small microphone can be arranged on the sound source side, and the generation source of noise (vibration sound) of about 300 Hz or less can be locally narrowed down and analyzed in detail. It is said.

JP 2013-79953 A

M. Asahina, T. Tomioka, S. Matsuo, T. Yoshimura: “Application of transfer path analysis to the vibration and noise of a railway vehicle”, The International Symposium on Speed-up and Sustainable Technology for Railway and Maglev System (STECH2015 ), 2015 Shinichi Maruyama dissertation, “Research on Vehicle Noise Reduction Technology Utilizing the Structure-Acoustic Reciprocity Theorem”, published on March 16, 1998

  As described above, according to the acoustic excitation method using the reciprocity theorem, it is possible to observe the source of noise (vibration sound) locally, and analyze the transmission path between the sound source and the observation position in the space. It becomes possible to perform the acoustic analysis including it in detail. On the other hand, an omnidirectional sound source is required as a simulated sound source, and in particular, the simulated sound source becomes large in the low frequency range, so the acoustic effect on the observation position cannot be ignored and can be regarded as a point sound source. It becomes a cause of reducing the analysis accuracy.

  The present invention has been made in view of the situation as described above, and its purpose includes analysis of a transmission path between a sound source and an observation position in an automobile, a railway vehicle, an aircraft, or other space. An acoustic analysis method and system thereof are provided.

  An acoustic analysis method according to the present invention is an acoustic analysis method for analyzing a sound field formed in a space, wherein an acoustic sensor is disposed at an observation position in the space, and a speaker is placed along a set virtual sound source surface. A transfer function acquiring step of measuring a sound particle velocity of sound emitted from the speaker by an acoustic particle velocity sensor disposed in front of the speaker while moving and acquiring a transfer function between the observation position and its surroundings; It is characterized by including.

  According to this invention, since the transfer function between the observation position and its surroundings is acquired by the acoustic sensor at the observation position and the acoustic particle velocity sensor in front of the speaker, the speaker can be moved along the virtual sound source plane. A transfer function between the observation position and each part of the virtual sound source surface can be obtained. These transfer functions enable acoustic analysis including analysis of the transfer path between the sound source and the observation position in the space.

  In the above-described invention, the speaker may be driven so that sound in a predetermined frequency range is measured by the acoustic particle velocity sensor. According to this invention, the transfer function can be acquired with high accuracy.

  In the above-described invention, the speaker may be a surface vibration speaker, and the predetermined frequency range may include a natural frequency of (1, 1) mode vibration of the speaker. According to this invention, the accuracy of the obtained transfer function can be improved.

  In the above-described invention, the acoustic sensor may be a microphone and measure sound pressure. In the above-described invention, the acoustic sensor may be an acoustic particle velocity sensor, and may measure an acoustic particle velocity. Furthermore, in the above-described invention, the acoustic sensor may further measure the intensity of sound. According to this invention, transfer functions for sound pressure, acoustic particle velocity, and sound intensity can be obtained, respectively.

  In the above-described invention, the virtual sound source surface may include a surface of a portion protruding into the space. According to this invention, even if there is a portion protruding in the space, acoustic analysis can be performed using this as a virtual sound source surface.

In the above-described invention, in the transfer function obtaining step, the transfer function G _n ( _n ) from the position x _n (n = 1 to N) to the observation position r for each of the divided surfaces obtained by dividing the virtual sound source surface into N pieces. _xn / r) is determined, and then the acoustic characteristic p (r) at the observation position r is determined from the acoustic particle velocity v ( _xn ) measured at the position _xn.
(Note that ΔS (x _n ) is the area of the divided surface corresponding to the position x _n ). According to this invention, it is possible to perform acoustic analysis for estimating acoustic characteristics such as sound pressure at the observation position from the transfer function.

  An acoustic analysis system according to the present invention is an acoustic analysis system for analyzing a sound field formed in a space, and is disposed on an acoustic sensor disposed at an observation position in the space and a set virtual sound source plane. An acoustic particle velocity sensor disposed in front of the speaker, and the acoustic particle velocity of the sound emitted from the speaker by the acoustic particle velocity sensor while moving the speaker along the virtual sound source surface. It includes a transfer function acquisition unit that measures and acquires a transfer function between the observation position and its surroundings.

  According to this invention, since the transfer function between the observation position and its surroundings is acquired by the acoustic sensor at the observation position and the acoustic particle velocity sensor in front of the speaker, the speaker can be moved along the virtual sound source plane. A transfer function between the observation position and each part of the virtual sound source surface can be obtained. These transfer functions enable acoustic analysis including analysis of the transfer path between the sound source and the observation position in the space.

  In the above-described invention, the speaker may be driven so that sound in a predetermined frequency range is measured by the acoustic particle velocity sensor. According to this invention, the transfer function can be acquired with high accuracy.

  In the above-described invention, the speaker may be a surface vibration speaker, and the predetermined frequency range may include a natural frequency of (1, 1) mode vibration of the speaker. According to this invention, the accuracy of the obtained transfer function can be improved.

  In the above-described invention, the acoustic sensor may be a microphone and measure sound pressure. In the above-described invention, the acoustic sensor may be an acoustic particle velocity sensor, and may measure an acoustic particle velocity. Furthermore, in the above-described invention, the acoustic sensor may further measure the intensity of sound. According to this invention, transfer functions for sound pressure, acoustic particle velocity, and sound intensity can be obtained, respectively.

  In the above-described invention, the virtual sound source surface may include a surface of a portion protruding into the space. According to this invention, even if there is a portion protruding in the space, acoustic analysis can be performed using this as a virtual sound source surface.

In the above-described invention, in the transfer function acquisition unit, the transfer function G _n ( _n ) from the position x _n (n = 1 to N) to the observation position r for each of the divided surfaces obtained by dividing the virtual sound source surface into N pieces. _xn / r) is determined, and then the acoustic characteristic p (r) at the observation position r is determined from the acoustic particle velocity v ( _xn ) measured at the position _xn.
(Note that ΔS (x _n ) is the area of the divided surface corresponding to the position x _n ). According to this invention, it is possible to perform acoustic analysis for estimating acoustic characteristics such as sound pressure at the observation position from the transfer function.

It is a flowchart which shows the acoustic analysis method in the Example of this invention. It is a figure which shows the model of the space explaining the acoustic analysis method. It is a block diagram of the acoustic analysis system in the Example of this invention. It is a perspective view of the apparatus used for the verification test. It is a graph which shows the estimation and the sound pressure level of measurement which show the result of a verification test.

  The acoustic analysis method according to the present invention will be described with reference to FIGS. Here, it mainly includes obtaining a transfer function between the observation position and its surroundings as part of the acoustic analysis, but in order to simplify the explanation, as an example of acoustic analysis, a space with noise around it is used. The case of estimating the sound pressure at the observation position in will be described.

  Referring to FIG. 1 together with FIG. 2, first, a space 1 to be acoustically analyzed is set (S1). As the space 1, for example, a space having a surface serving as a sound source such as a wall surface that propagates sound from the outside to the inside of the space 1 such as the inside of a vehicle such as a train or the interior of a car is assumed.

  Here, the space 1 does not need to be partitioned entirely by physical wall surfaces, and may be, for example, an open space having an opening portion communicating with the outside. In such a case, it is assumed that there is a continuous surface for sound propagation inside the opening. Then, these surfaces that propagate the sound into the space 1 including the wall surface and the opening are set as the virtual sound source surface 2 that becomes the sound source in the space 1. Further, in the case where there is a seat provided in the interior of the vehicle, a fixture such as a console box of an automobile, and the like provided in the room, the virtual sound source surface 2 protrudes along the fixture, that is, inside the space 1. It is good to set so that the surface of a site | part may be included. When there is a sound source in the room, the virtual sound source surface 2 is set on the surface of the sound source, and the sound source is arranged outside the virtual sound source surface 2. Note that it is not necessary to set the virtual sound source plane 2 for a portion where there is clearly no external sound propagation or a portion where sound propagation can be ignored.

Subsequently, a speaker that moves each position x _n (n = 1 to N) on the virtual sound source surface 2 and an acoustic particle velocity sensor that moves along the front in accordance with this are arranged, and acoustic particles at each position x _n are arranged. The velocity and the acoustic characteristic at the observation position r in the space 1 are measured, and the frequency response function representing the ratio and phase difference between the magnitudes of the acoustic characteristics from the position _xn to the observation position r, that is, the transfer function, by these relations (Green function) G _n (x _n / r) is acquired (S2). Here, as the acoustic characteristics, various physical quantities having frequency characteristics related to sound such as sound pressure, acoustic particle velocity, and sound intensity (acoustic intensity, unit: W / m ² ) can be used. Here, it is assumed that a transfer function for sound pressure is obtained. Each position _xn is a position of each divided surface obtained by dividing the entire virtual sound source surface 2 into N pieces. Details of this transfer function acquisition step (S2) will be described later.

Subsequently, in a state where the virtual sound source surface 2 is propagating sound such as noise in the space 1, the acoustic particle velocity at the position _xn of the dividing surface is measured (S3). Here, the acoustic particle velocity sensor is moved along the virtual sound source plane 2, and n is changed from 1 to N to measure the acoustic particle velocity at the position _xn . Here, as the acoustic particle velocity sensor, the acoustic particle velocity sensor may be removed and used, or another acoustic particle velocity sensor may be used.

Then, the sound pressure p (r) at the observation position r is estimated from the acoustic particle velocity measured along the virtual sound source surface 2 (S4). Are multiplied to the transfer function described above the acoustic particle velocity v (x _n) measured at each position x _n, it may be further added for every position x _n. That is, the sound pressure p (r) at the observation position r is expressed by the following “Equation 1” as an area of a divided surface obtained by dividing the virtual sound source surface 2 with ΔS (x _n ) corresponding to each position x _n. Can do.

As described above, it has been shown that the sound analysis at the observation position r in the space 1 where the sound propagates can be estimated from the transfer function. Thus, by acquiring the transfer function from each position _xn on the virtual sound source surface 2 to the observation position r, for example, the _order of the contribution from each position _xn to the sound pressure at the observation position r is ordered. It is also possible to perform other acoustic analysis in the space 1 such as estimating the sound pressure distribution in the space 1. Even if a transfer function related to other acoustic characteristics is obtained instead of the sound pressure, the acoustic analysis for estimating the respective acoustic characteristics p (r) can be similarly performed using Equation 1.

  Next, as an acoustic analysis method using the acoustic analysis system according to the present invention, details of the above-described transfer function acquisition step (S2) will be described with reference to FIG.

  As shown in FIG. 3, the acoustic analysis system 10 is a system for analyzing a sound field formed in the space 1, and a speaker 3 arranged along a virtual sound source plane 2 set in the space 1, An observation position acoustic sensor 4 disposed at an observation position r in the space 1 and a speaker front acoustic particle velocity sensor 5 disposed in front of the speaker 3 are included. The speaker 3, the observation position acoustic sensor 4, and the pre-speaker acoustic particle velocity sensor 5 are connected to the arithmetic processing device 12. The arithmetic processing unit 12 is, for example, the ratio of the magnitude of the acoustic particle velocity signal generated by the speaker 3 measured by the pre-speaker acoustic particle velocity sensor 5 and the sound signal received by the observation position acoustic sensor 4. And phase difference can be measured. The arithmetic processing unit 12 includes a transfer function acquisition unit that can acquire a transfer function.

  The speaker 3 can generate a sound having a predetermined frequency by a signal from the arithmetic processing unit 12. That is, the arithmetic processing unit 12 also has at least functions of an oscillator and an amplifier. As the speaker 3, it is preferable to minimize the influence of sound on the space 1 in the absence of output, and it is preferable that the speaker 3 be sufficiently small and thin with respect to the wavelength of sound used for measurement. As such a speaker 3, a surface vibration speaker etc. are suitable, for example. Further, when the speaker 3 is a surface vibration speaker and the sound generated by the speaker 3 is representatively measured by the acoustic particle velocity sensor 5 before the speaker, the diaphragm for generating the surface vibration is uniformly in the 0 to 1st mode. What can vibrate is preferable. As such a surface vibration speaker, for example, a piezoelectric speaker can be used. In addition, a small speaker, a smartphone, or the like can be used as long as it can generate sound of a predetermined frequency bandwidth. In particular, in the case of a smartphone, it is not necessary to separately provide an amplifier or the like, and if an application for generating sound is installed, the functions of the oscillator and amplifier of the arithmetic processing unit 12 can be made unnecessary, which can be advantageous in handling. .

  The observation position acoustic sensor 4 can measure a specific acoustic characteristic used for a transfer function to be obtained, such as a microphone capable of measuring a sound pressure, or can measure an acoustic characteristic that can be converted into the specific acoustic characteristic. It is. The acoustic particle velocity sensor 5 before the speaker is a sensor capable of measuring the acoustic particle velocity, has high sensitivity in a specific direction, and is not easily affected by noise from an unintended direction. Therefore, the particle velocity of the medium (air) that is acoustic particles can be measured with high accuracy.

Here, a sound having a frequency having a bandwidth is generated from the speaker 3 to measure the acoustic particle velocity of the sound generated by the acoustic particle velocity sensor 5 before the speaker, and at the observation position r by the observation position acoustic sensor 4. Measure acoustic characteristics such as sound pressure. In the transfer function acquisition unit of the arithmetic processing unit 12, the phase difference and the magnitude ratio between the acoustic particle velocity measured by the acoustic particle velocity sensor 5 before the speaker and the acoustic characteristics of the sound measured by the observation position acoustic sensor 4 are calculated. Then, a transfer function that is a frequency response function is calculated. Thereby, the transfer function G ₁ (x ₁ / r) when the speaker 3 is arranged at the position x ₁ can be acquired.

  Here, in the measurement of the acoustic characteristics, it is preferable that there is no noise in the surroundings. However, even if noise is generated, transmission is possible if a loud enough sound is generated from the speaker 3. You can get the function.

Further, the position of the speaker 3 is moved along the virtual sound source plane 2, and similarly, the acoustic characteristic at the observation position r when it is arranged at the position _xn is measured, and the transfer function G _n (x _n / r) is obtained. To do. That is, the position of the surface vibration speaker 3 is moved and arranged at each position x _{n where n} is changed from 1 to N, and transfer functions G ₁ (x ₁ / r) to G _N (x _N / r) are set. get. As a result, acoustic analysis using the transfer function as described above becomes possible.

Here, since the acoustic particle velocity sensor 5 before the speaker is moved in accordance with the movement of the speaker 3, the acoustic particle velocity can be measured including the influence of the surrounding wall surface where the sound is reflected at each position _xn. By obtaining a transfer function using this, an accurate transfer function can be obtained, and an accurate acoustic analysis can be performed.

  The observation position acoustic sensor 4 is, for example, a microphone that can measure sound pressure. By using the microphone as an acoustic particle velocity sensor, the acoustic particle velocity at the observation position r can be measured, and various kinds of forces such as a force acting on the field can be measured. You can even get information. For example, this can be converted into a sound pressure or a sound pressure level. Moreover, as described above, other acoustic characteristics such as sound intensity may be measured, and an acoustic sensor suitable for each may be used.

  Further, when acquiring the transfer function, the speaker 3 to be moved along the virtual sound source plane 2 may be photographed with a camera, and the position thereof may be obtained by image analysis. This makes it easy to continuously process the acquisition of transfer functions corresponding to each of a number of positions.

[Verification test]
With respect to the acoustic analysis method described above, a verification test performed with a simple model will be described with reference to FIGS.

  As shown in FIG. 4, a sound source speaker 27 is arranged inside a rectangular parallelepiped box 20 having a hollow inside, and an observation position acoustic sensor 4 is arranged at an observation position r. As the observation position acoustic sensor 4, a microphone capable of measuring sound pressure was used. Further, the surfaces 21 to 25 of the box 20 that are not in contact with the floor surface are each part of the virtual sound source surface 2 and placed in a room without noise so that other virtual sound source surfaces need not be considered. As the box 20, a corrugated cardboard box having a 1.0 mm thick aluminum plate attached from the outside was used. Further, as the sound source speaker 27 inside the box 20, a general speaker having a cone-shaped diaphragm was used.

  First, as shown in FIG. 4A, the speaker 3 is arranged at a position along the surface 21 of the box 20, generates a sound having a frequency having a predetermined bandwidth, and is arranged on the front surface of the speaker 3. The acoustic particle velocity was measured by the pre-acoustic particle velocity sensor 5. As the speaker 3, a small surface vibration speaker was used. At the same time, the sound pressure was measured by the observation position acoustic sensor 4 at the observation position r. Similarly to the above-described example, the transfer function between these was obtained from the measurement results of the acoustic particle velocity sensor 5 before the speaker and the observation position acoustic sensor 4. Similarly, transfer functions up to the observation position r were obtained for the surfaces 22 to 25, respectively.

  Next, as shown in FIG. 4B, a sound having a frequency having a predetermined bandwidth is generated by the speaker 27 inside the box 20, and the sound source is generated by the acoustic particle velocity sensor disposed in front of each surface 21 to 25. The acoustic particle velocity was measured by the in-plane acoustic particle velocity sensor 6. As the acoustic particle velocity sensor 6 in front of the sound source surface, the acoustic particle velocity sensor 5 in front of the speaker can be substituted. Using the acoustic particle velocity measured by the acoustic particle surface acoustic particle velocity sensor 6, the sound pressure level at the observation position r was estimated from the transfer function from each surface 21 to 25 to the observation position r. That is, as in the example of acoustic analysis described above, assuming that the virtual sound source surface 2 is divided into five surfaces of the box 20, the product of the transfer function and the acoustic particle velocity for the five surfaces is obtained and these are obtained. The sound pressure level at the observation position r is simply estimated by adding.

  On the other hand, a sound having a frequency having a predetermined bandwidth was generated by the speaker 27 inside the box 20 in the same manner as described above, and the sound pressure level was measured by the observation position acoustic sensor 4. That is, the sound pressure level at the observation position r due to sound from inside the box 20 is actually measured.

  FIG. 5 shows the frequency characteristics of the sound pressure level measured at the observation position r together with the frequency characteristics of the sound pressure level at the observation position r estimated using the transfer function. Both sound pressure levels were almost the same in the frequency range of 150 to 250 Hz. That is, although the virtual sound source surface 2 is a simple model divided into only five surfaces of the box 20, a transfer function that can be used for acoustic analysis can be obtained with high accuracy at least in the frequency range described above. I know that.

  By the way, in this verification test, the frequency range of the sound to be measured by the acoustic particle velocity sensor 5 before the speaker is set to 50 to 400 Hz, and the speaker 3 is driven so as to generate a sound having a bandwidth including the same frequency range. Have acquired. As described above, it is preferable that the frequency range for acquiring the transfer function is determined in accordance with the frequency range of the sound that can be generated by the surrounding environment and the sound to be analyzed, because the calculation process can be saved. In addition, the acoustic analysis can be performed by narrowing down to a frequency range where a transfer function with higher accuracy can be obtained.

  In particular, the natural frequency in the vibration of the (1, 1) mode of the surface vibration speaker used for the verification test as the speaker 3 is 180 Hz. As described above, the sound pressure level can be estimated more accurately at 150 to 250 Hz including this natural frequency. In other words, if the frequency range of the sound used to obtain the transfer function is set to a specific frequency range that includes the natural frequency in the vibration of the (1, 1) mode of the surface vibration speaker, the transfer function can be obtained more accurately. I think it can be done. For example, when selecting a surface vibration speaker to be used for measurement, the above-mentioned natural frequency is included in the frequency range of the sound to be measured, so that the accuracy of the obtained transfer function can be improved.

  Up to this point, typical embodiments according to the present invention and modifications associated therewith have been described. However, the present invention is not necessarily limited thereto, and can be appropriately changed by those skilled in the art. That is, those skilled in the art will be able to find various alternative embodiments and modifications without departing from the scope of the appended claims.

DESCRIPTION OF SYMBOLS 1 Space 2 Virtual sound source surface 3 Speaker 4 Observation position acoustic sensor 5 Pre-speaker acoustic particle velocity sensor 10 Acoustic analysis system r Observation position

Claims (16)

An acoustic analysis method for analyzing a sound field formed in a space,
An acoustic sensor is disposed at an observation position in the space, and an acoustic particle velocity of sound emitted from the speaker is measured by an acoustic particle velocity sensor disposed in front of the speaker while moving the speaker along a set virtual sound source plane. An acoustic analysis method comprising a transfer function acquisition step of measuring and acquiring a transfer function between the observation position and its surroundings.   The acoustic analysis method according to claim 1, wherein the speaker is driven so that sound in a predetermined frequency range is measured by the acoustic particle velocity sensor.   The acoustic analysis method according to claim 2, wherein the speaker is a surface vibration speaker, and the predetermined frequency range includes a natural frequency of (1, 1) mode vibration of the speaker.   The acoustic analysis method according to claim 1, wherein the acoustic sensor is a microphone and measures sound pressure.   The acoustic analysis method according to claim 1, wherein the acoustic sensor is an acoustic particle velocity sensor and measures an acoustic particle velocity.   The acoustic analysis method according to claim 4, wherein the acoustic sensor further measures a sound intensity.   The acoustic analysis method according to claim 1, wherein the virtual sound source surface includes a surface of a portion protruding into the space. In the transfer function acquisition step, the transfer function G _n (x _n / r) from the position x _n (n = 1 to N) to the observation position r for each of the divided surfaces obtained by dividing the virtual sound source surface into N pieces. Decide
Thereafter, the acoustic characteristic p (r) at the observation position r is calculated from the acoustic particle velocity v (x _n ) measured at the position _xn.
8. The acoustic analysis method according to claim 1, wherein analysis is performed by (where ΔS (x _n ) is an area of the divided surface corresponding to the position x _n ). An acoustic analysis system for analyzing a sound field formed in a space,
An acoustic sensor disposed at an observation position in the space;
A speaker arranged on the virtual sound source surface to be set;
An acoustic particle velocity sensor disposed in front of the speaker,
Transfer that obtains a transfer function between the observation position and its surroundings by measuring the acoustic particle velocity of sound emitted from the speaker by the acoustic particle velocity sensor while moving the speaker along the virtual sound source plane An acoustic analysis system including a function acquisition unit.   The acoustic analysis system according to claim 9, wherein the speaker is driven so that sound in a predetermined frequency range is measured by the acoustic particle velocity sensor.   The acoustic analysis system according to claim 10, wherein the speaker is a surface vibration speaker, and the predetermined frequency range includes a natural frequency of (1, 1) mode vibration of the speaker.   The acoustic analysis system according to claim 9, wherein the acoustic sensor is a microphone and measures a sound pressure.   The acoustic analysis system according to claim 9, wherein the acoustic sensor is an acoustic particle velocity sensor and measures an acoustic particle velocity.   The acoustic analysis system according to claim 12 or 13, wherein the acoustic sensor further measures a sound intensity.   The acoustic analysis system according to claim 9, wherein the virtual sound source surface includes a surface of a portion protruding into the space. In the transfer function acquisition unit, the transfer function G _n (x _n / r) from the position x _n (n = 1 to N) to the observation position r for each of the divided surfaces obtained by dividing the virtual sound source surface into N pieces. Decide
Thereafter, acoustic characteristics p of the observation position r from the acoustic particle velocity v _{(x n)} at the position _{x n} of the (r)
The acoustic analysis system according to claim 9, wherein the analysis is performed (where ΔS (x _n ) is an area of the divided surface corresponding to the position x _n ).