JP2002101500A - Sound field measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measurement system that measures a reproduction sound field characteristic of a multi-channel acoustic system that can perform sound field measurement with high accuracy and a simple device configuration in a short time. SOLUTION: A microphone system having a multi-point microphone 5 is installed to a measurement sound field 1 in which a reproduction speaker 4 is installed. A reproduction player 9 reproduces a measurement signal recorded in advance. A signal of a microphone 5i placed just before the speaker is used for a trigger signal. A multi-channel microphone amplifier 6 amplifies the microphone signal, a multi-channel analog/digital converter converts the amplified signal into a digital signal, a computer 11 captures the digital signal data and analyzes the data so as to form a sound field measurement system that measures the multi-channel sound field reproduction system in a short time with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a sound field measuring device for measuring a reproduced sound field using a computer.

[0002]

2. Description of the Related Art Conventionally, a sound field measuring device has been disclosed in Japanese Unexamined Utility Model Publication No.
No. 641 is known. In FIG. 10, reference numerals 5a, 5b, and 5c denote a plurality of microphones, and output signals of the microphones 5a, 5b, and 5c are supplied to a multi-channel microphone amplifier 6. The loudspeaker 4 installed in the measurement sound field 1 of the acoustic measurement device having such a configuration is provided with an oscillator 2 as in the conventional example.
The sound signal oscillated by the power amplifier 3 is supplied to the speaker 4 via the power amplifier 3, and the measurement signal is output from the speaker 4 to the measurement sound field 1.
Microphones 55a, 5a and 5
The sound is received by b and 5c, and the sound field characteristics are measured by the FFT analyzer 7 via the multi-channel microphone amplifier 6.

[0003]

In this acoustic measuring apparatus, the transmitter and the data fetching unit are individually operated systems, and include oscillators for independently generating clocks. Therefore, the respective oscillation frequencies are often different, and it is not possible to perform measurement synchronized with the oscillator and the measuring instrument, so that it is difficult to perform in-phase addition processing, and it is difficult to accurately measure the sound field such as phase characteristics. .

Further, when measuring a multi-channel sound reproduction system having a plurality of speakers, a signal must be added to each speaker for measurement, and much time is required for the measurement.

Furthermore, since the direction of arrival of a sound wave affects the direction, size, and spread of a sound image, it is important to measure the direction of arrival of a three-dimensional sound wave. In the conventional microphone system shown in FIG. 10, since the three microphones are arranged on a plane that stands upright with respect to the speaker, the detection sensitivity in the front-back direction is poor, and it is difficult to detect the three-dimensional sound arrival direction. . Therefore, a highly accurate sound field cannot be evaluated by the conventional measurement system.

[0006] Measuring the distance from each speaker to each microphone is important for knowing the sound field when each channel is reproduced simultaneously. However, this measuring system has a disadvantage that the distance between the speaker and the microphone cannot be accurately detected because the oscillator and the measuring device are not separated and perform synchronized measurement.

The present invention makes it possible to correct the sampling frequency difference between the transmitter and the measuring system in such an acoustic measuring apparatus and improve the S / N of the measurement by the in-phase addition processing. In addition, measurement of each channel of the multi-channel sound system can be performed by one measurement, and measurement time can be reduced. It is another object of the present invention to measure the direction of arrival of a sound wave, the distance between a speaker and a microphone with high accuracy, and to obtain high-accuracy various acoustic characteristics.

[0008]

In order to solve this problem, a sound field measuring apparatus according to the present invention comprises a plurality of regular tetrahedrons having different ridge lengths, each of which has a plurality of small microphones at each apex. A multi-point microphone system including a microphone, a microphone amplifier for amplifying a microphone signal, an input unit for taking an output signal of the microphone amplifier into a computer, a computer, signal analysis software, and an audio device such as a speaker. And a recording medium on which a measurement signal for recording is recorded. The signal analysis software of the present invention includes a means for calculating a sampling frequency difference between the transmitting unit and the measuring device from the measurement result, a data cutout position control means during the averaging process using the calculation result, and an in-phase addition means It is provided with.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

(Embodiment 1) FIG. 1 shows an acoustic measuring apparatus according to Embodiment 1 of the present invention. In FIG. 1, 1 is a measurement sound field, 9 is a reproduction player, 3a and 3b are power amplifiers,
Reference numerals a and 4b denote speakers, 5a to 5h denote multipoint microphones, 6 denotes a multichannel microphone amplifier, 10 denotes a multichannel A / D converter, and 11 denotes a personal computer.

The operation of the sound field measuring system configured as described above will be described below. The measurement signal is recorded in advance on a recording medium such as a CD, DVD, DAT, semiconductor memory, or hard disk, and the reproduction player 9
The signal for measurement is reproduced with the power amplifier 3
The signals are amplified by a and 3b and applied to the speakers 4a and 4b. The sound wave reproduced from the speaker is the microphone 5a installed in the sound field.
５5g, and a microphone 5i installed immediately before the speaker 4a.
These signals are amplified by the multi-channel microphone amplifier 6,
The signal is converted into a digital signal through the multi-channel A / D converter 10 and sent to a personal computer as digital data.

The microphone 5i is installed immediately before the speaker, and the signal of the microphone 5i works as a trigger signal. When the signal of the microphone 5i reaches a certain level, each microphone 5a
The signals of .about.5g and the signal of 5i are captured and stored as digital signals in the computer. After the measurement is completed, the digital signal captured by the computer is passed through a programmed analyzer 12, through which means for analyzing the sampling frequency difference between the player and the measuring instrument, means for correcting the data extraction position,
It has in-phase addition means, enables high-accuracy signal analysis, and performs various acoustic analyses.

The sound field measuring system thus configured has an advantage that it is not necessary to send a signal from the measuring instrument to the sound system to be measured since the reproducing player of the acoustic system is used as the transmitter. Further, since the microphone 5i installed immediately before the speaker is used as the trigger signal, there is no need to separately extract an electric signal as the trigger signal, and there is an advantage that the measurement can be easily performed without modifying the acoustic system to be measured. Furthermore, since the data is stored after the trigger signal is generated, only necessary measurement data can be stored in the computer, and there is a feature that no extra memory is required. Further, since the signal of the microphone 5i is output almost simultaneously with the electric signal, the delay time between the speaker and the microphone system can be measured.

The multi-channel microphone system composed of the microphones 5a to 5g is composed of microphones 5a, 5b, 5c and 5d arranged at the vertices of a regular tetrahedron, and microphones 5e arranged at the vertices of a regular tetrahedron arranged therein. , 5f, 5g, 5d
It is composed of The microphone 5d serves as a shared microphone for a regular tetrahedron having a long ridge and a short regular tetrahedron, and has a feature that the number of microphones can be reduced.

(Embodiment 2) FIG. 2 shows a configuration diagram of a multipoint microphone system according to Embodiment 2 of the present invention, and shows an enlarged view of the microphone system of the present invention shown in FIG.
In FIG. 2, 5a to 5g are microphones, 12a to 12g are microphone holders, 13d to 13g are spacers, 14 is a base, and 15 is a stand. The operation of the microphone system configured as described above will be described below. The microphones 5a to 5g are installed at the apexes of tetrahedrons having different lengths, and the microphone holders 12a to 12g have a function of fixing the microphones under the same conditions, and some of them have spacers for maintaining the microphone height. Base 1 through 13d-13g
It is fixed to 4. The base 14 is attached to a stand 15 and is configured to be installed at an arbitrary place so that measurement can be performed.

In such a microphone system, the microphones 5a, 5f, 5g, 5d are arranged at the apexes of a tetrahedron having a long ridge composed of the microphones 5a, 5b, 5c, 5d.
And a microphone placed at the top of a tetrahedron with a short ridge. Such a microphone configuration has a three-dimensional arrangement structure, and has an advantage that the arrival direction of a sound wave can be measured. If the distance between the microphones is long, the directional resolution ability of the low sound region is high, but the phase around the distance is large in the high sound region, and the resolution is reduced due to the influence of the reflected wave. On the other hand, if the distance between the microphones is short, the performance of the directional resolution in the low range is inferior, but there is a feature that the direction of arrival of the sound wave to the higher range can be measured. The microphone system according to the present invention has two or more microphone distances at the same time, and enables highly accurate measurement over a wide frequency range. Further, the microphone 5d is commonly used for a regular tetrahedron arrangement having two ridges, and has an advantage that the number of microphones can be reduced.

Microphones 5a to 5g and microphone holder 12a
-12 g are integrated, and all microphones have almost the same characteristics, so that it is only necessary to prepare a minimum number of spare microphones. The height of the microphone is characterized in that it can be easily and accurately attached even at the measurement site by being attached via the spacers 13d to 13g.

(Embodiment 3) FIG. 3 is a configuration diagram of a multipoint microphone system according to Embodiment 3 of the present invention, and shows an enlarged view of the microphone system. In FIG. 3, 5h is a microphone, 12h is a microphone holder, and 13h is a spacer. The operation of the microphone system configured as described above will be described below. The microphone system is provided with two-stage microphones 5d and 5h at the center, and the microphone 5h is arranged on the same plane as the microphones 5e, 5f and 5g. Therefore, by providing the microphone 5h at the center from the microphone system described in FIG. 2, the microphone can be measured not only on the outer surface of the tetrahedron but also inside the tetrahedron. There is an advantage that the space at the position where the microphone system is installed can be measured densely. Furthermore, there is a feature that the resolution of the sound wave arrival direction with respect to the horizontal plane can be increased.

(Embodiment 4) FIG. 4 shows a configuration diagram of a measuring sound source according to Embodiment 4 of the present invention. In FIG. 4, reference numerals 16a, 16b and 16c denote silence parts, 17a and 17b
Is a signal part. The operation of the measurement signal configured as described above will be described below. Figure 4 shows 2c
5 shows a time characteristic of a measurement signal for h. L at the beginning of the signal
Both the ch and the Rch have a non-signal portion 16, and then the Lch has a measurement signal in which an impulse or a time stretch pulse is repeatedly reproduced, and then the non-signal portion 16 is followed by a measurement signal of the other channel. It is configured. When measuring the sound field of an automobile or the like with the non-signal section 16a having a length of about 2 to 30 seconds, the measurer pressed the reproduction start button in order to reproduce the measurement signal with a player mounted in the vehicle interior. Later, there is a feature that can be used as a time until the user goes outside and starts the measurement system. Further, the measurement signal of the present invention can be obtained by simply pressing the play button once.
h can be alternately reproduced for measurement, which has the effect of greatly reducing the measurement time. The silent section 16b provided between the Lch and Rch signals is, for example, Lc
By setting the time from when the sound h stops until the reverberation component disappears and the sound field becomes quiet, there is an advantage that the sound of each channel can be measured independently.

In the conventional measuring method, a sound reproducing system is modified to take out a signal for synchronizing with a measuring instrument and a trigger signal which are necessary for high-accuracy sound measurement including a phase. Needed. However, in the system of the present invention, this measurement sound source is a CD, DVD, DA
This is obtained by reproducing a signal recorded on a digital reproduction device medium such as T, and has the merit that measurement can be performed as it is without modifying the sound reproduction system.

(Embodiment 5) FIG. 5 is a diagram showing a measurement signal configuration of a multi-channel system according to Embodiment 5 of the present invention, in which 5.1 channels recorded for a DVD player or the like are used.
2 shows a configuration of a measurement signal for measuring a multi-channel sound system. In FIG. 5, 17a, 17b, 1
7c, 17d, 17e, and 17f are measurement signals of each channel. The operation of the measurement signal configured as described above will be described below. Following the silent section 16a having a length of 2 to 30 seconds, the signal can be sequentially reproduced from the Lch to the subwoofer SW. Silence sections 16b, 16c, 16d, 1 provided between channels.
6. For example, 16f and 16g have the advantage that the sound of each channel can be measured independently by setting the time from when the Lch sound stops until the reverberation component disappears and the sound field becomes quiet.

By using this measurement signal, 5.1-channel measurement can be performed at a time by pressing the play button once, so that the measurement time can be greatly shortened. There is an advantage that the phase can be measured accurately. This measurement signal has the same effect without affecting the measurement result even if the order of the reproduced signals is changed.

FIG. 6 shows an example of one speaker measured using the measurement signal of the present invention shown in FIG. 4, and shows the relationship between the measurement signal and its response signal. In FIG. 6, S1
To Sn are measurement signals, M1 to Mn are speaker response signals, T1 is the number of sampling time points of the measurement signals,
T2 indicates the number of sampling time points of the measurement signal whose response characteristics have been measured. The measurement signal is composed of a signal such as an impulse or a time stretch pulse in which the same signal is arranged in n waves. Each signal is composed of T1 sampling time points, and a signal composed of n waves is (T
1 · n) sampling time points.

In the measuring system of the present invention, the signal reproducing player and the measuring A / D converter have separate oscillators, respectively, and therefore have different sampling frequencies. Making measurement difficult.

(Embodiment 6) FIG. 7 is a diagram showing a sampling frequency detection and averaging algorithm according to a sixth embodiment of the present invention, and particularly shows a sampling frequency difference correction algorithm and a synchronous addition process. In FIG. 7, reference numeral 21a denotes a first wave cutout process, 21b denotes an i-th wave cutout process, 22a and 22b denote FFT processes, 23 denotes a complex division process, 24 denotes an inverse FFT process, and 25 denotes a time characteristic peak position detection process. , 26 are position correction processing at the time of cutting out the i-th wave,
27 is an FFT process, 28 is an addition process, 29 is an average calculation,
Reference numeral 30 denotes a transfer function characteristic calculation process. The operation of the sampling frequency difference correction processing and the synchronous addition processing configured as described above will be described below. For example, the first wave M1 of the measurement signal shown in FIG. 6 is cut out by the first wave cutout processing 21a, and the frequency characteristic is obtained by the FFT processing 22a, and the result is set to P1 (jω). Next, the i-th wave extraction processing 21
In step b, the signal of the i-th wave Mi is cut out. The cutting position is T1
(I-1) It cuts out from the +1 sampling time point, obtains frequency characteristics by FFT processing 22b, and
Pi (jω). Next, complex division processing 23 is performed for each frequency as described below to calculate H (jω).

H (jω) = Pi (jω) / P1 (jω) Then, a time characteristic h (t) is calculated by the inverse FFT processing 24. As the time characteristic, a characteristic like an impulse response is obtained, and the peak position is detected by the peak position detection 25.
The peak position changes depending on the sampling frequency shift between the reproducing player and the measuring instrument. As shown in the figure, it is assumed that one measurement signal is composed of T1 sampling time points, while the same portion of the signal is acquired at T2 sampling time points. As a result, when the impulse peak position is at the n sampling time point, the relationship between T1 and T2 can be obtained as T2 = (T1 * (i-1)-(n-1)) / (i-1). . Thus, if there is a peak at the first sampling time point, n = 1, and
It shows that there is no sampling frequency difference.

Next, when the response signal of the i-th wave is cut out from the measurement signal, the cutout position is adjusted by the position adjustment 26 and cut out, and after the FFT processing 27, the addition processing 28 is performed. After that, the data is averaged by an averaging process 29 to calculate the transfer characteristic. As described above, since the extraction position can be adjusted in consideration of the sampling frequency difference, it is possible to extract under the same time waveform condition even if the signal position of the measurement result is unclear due to the sampling frequency difference. . The signal extracted in this way is then subjected to FFT processing, averaging processing is performed on the frequency characteristic, and the transfer characteristic is obtained, whereby averaging processing by synchronous addition, which was difficult with the conventional measurement method, is also possible. And the characteristic that a measurement result with a high S / N can be obtained.

(Embodiment 7) FIG. 8 is a diagram showing a configuration of a two-channel sound system measurement sound source according to a seventh embodiment of the present invention relating to a measurement signal. In FIG. 8, reference numeral 18a is provided before a measurement signal 17a. The time stretch pulse 18b is the last time stretch pulse provided, and 19a and 19b are signals such as a sine wave, a sine sweep wave, and random noise. The operation of the measurement signal configured as described above will be described below.
The non-signal section 16a is, for example, the time required from the time when the medium on which the measurement signal of the present invention is recorded is inserted into the player and the play button is pressed until the measurement system is operated. It is preferable to provide a time of about 2 to 30 seconds. The time stretch pulse signal 18a is provided before and after signals 19a and 19b such as a sine wave and a swept sine wave. The number of sampling points between the two time stretch pulses is known in advance, and there is an effect that the sampling frequency difference can be known by detecting the number of sampling time points of the response signal of the measurement result.

(Eighth Embodiment) FIG. 9 shows a sampling frequency detection and signal analysis algorithm according to an eighth embodiment of the present invention, and shows a method of analyzing a signal measured using the measurement signal shown in FIG. In FIG. 9, reference numeral 31a denotes a first time stretch pulse extraction process, and 32b denotes a last sweep pulse signal extraction process. The operation of the sampling frequency difference detection algorithm and the averaging processing method configured as described above will be described below.

The first time stretch pulse response section is cut out from the response signal of the measurement result (31a), and the FFT processing 2 is performed.
2a is executed, and its frequency characteristic is set to P1 (jω). Next, the sampling time point of T3 is moved, and the last time stretch pulse response section is cut out 31b, FF
T processing 22b is executed, and its frequency characteristic is represented by P2 (jω).
And Next, the division processing unit 23 performs a complex operation of H (jω) = P2 (jω) / P1 (jω). Next, the inverse FFT of H (jω)
Processing 24 obtains the time characteristic h (t). This h (t)
Are the sampling frequency f1 of the reproducing system player and the sampling frequency f of the measuring A / D converter.
It changes depending on the relationship with 2. Assuming that the peak position np and the sampling frequencies of the player and the measuring device are f1 and f2, the relationship is represented by the following equation.

F1 = (T3 / (T3-np + 1)) · f2 Therefore, if the peak point of h (t) is at the first sampling point, it can be understood that the sampling frequency of the device is the same. The sampling frequency difference is calculated from the peak position. Using this result, the cutout position of the part to be analyzed from the measurement signal is corrected and cut out,
It is to be analyzed. If the measurement signal is a signal that is repeated with the same signal, the next time the i-th wave is cut out, the cut-out position is changed, and the cut-out point is changed so as to be the wave front of the i-th wave. Extraction, FFT processing, and addition processing are performed on frequency characteristics. This process is repeatedly performed as shown in FIG. 9 to obtain an averaged signal.

By performing the above operation, there is an advantage that the sampling frequency of the transmitting section and the capturing section can be obtained with high accuracy. In addition, since the measurement can be performed in consideration of the sampling frequency difference, the phase of the response signal can be matched with high accuracy even when averaging the continuously measured signals, and high S / N can be measured. Has the effect of becoming

[0033]

As described above, according to the present invention, the use of a multi-microphone system arranged at the vertices of a double tetrahedron makes it possible to measure the direction of arrival of sound waves over a wide band, By averaging the characteristics of the microphones, a remarkable effect can be obtained in that significant deviations in the sound measurement results due to subtle deviations in the microphone installation location can be eliminated.

Further, according to the present invention, in a digital acoustic measurement, a measurement signal is transmitted from the measuring instrument to the sound system to be measured, which is necessary when a transfer characteristic is obtained by using a normal measuring instrument. It is not necessary to take out a signal from a part of the measurement, and a remarkable effect that measurement can be obtained. Then, the measurement signal transmission unit can use a player of an acoustic system. In this case, even if the measurement signal transmission unit and the A / D converter of the measurement unit have different frequencies, the sampling frequency is automatically corrected. , And a remarkable effect that highly accurate measurement becomes possible is obtained.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an acoustic measurement device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a multipoint microphone system according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a multipoint microphone system according to a third embodiment of the present invention.

FIG. 4 is a configuration diagram of a measurement sound source according to a fourth embodiment of the present invention.

FIG. 5 is a diagram illustrating a measurement signal configuration of a multi-channel system according to a fifth embodiment of the present invention.

FIG. 6 is a diagram showing time characteristics of measurement data of a measurement signal and a response signal.

FIG. 7 is a diagram showing a sampling frequency detection and averaging algorithm according to a sixth embodiment of the present invention;

FIG. 8 is a configuration diagram of a two-channel sound system measurement sound source according to a seventh embodiment of the present invention.

FIG. 9 is a diagram showing a sampling frequency detection and signal analysis algorithm according to an eighth embodiment of the present invention.

FIG. 10 is a configuration diagram of a conventional acoustic measurement device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Measurement sound field 2 Oscillator 3 Power amplifier 4 Speaker 5 Microphone 6 Multi-channel microphone amplifier 7 FFT analyzer 8 Microcomputer 9 Playback player 10 Multichannel A / D converter 11 Computer 12 Microphone holder 13 Spacer 14 Microphone system base 15 Stand 16 Measurement Silence part in signal 17 Measurement signal part where the same signal is repeatedly reproduced a plurality of times 18 Pulse or sweep signal provided before main signal 19 Signal part

Claims (11)

[Claims] 1. A multipoint microphone system in which a small microphone is installed at each vertex of at least two or more regular tetrahedrons having different lengths of one side, a microphone amplifier for amplifying the microphone signal, and an amplifier A / which converts the converted signal into a digital signal
A sound field measuring apparatus comprising: a D conversion unit; input means for inputting digital data into a computer; a computer; and analysis software. 2. A multi-point microphone system in which a small microphone is installed at each vertex of two or more tetrahedrons having different ridge lengths and at least one microphone is matched with at least one vertex of the tetrahedron. The sound field measuring device according to claim 1, wherein: 3. A microphone having a plurality of small microphones, a microphone holder of the same shape for holding the small microphone, a spacer connected to the microphone holder, and a mechanism for holding the microphone holder and the spacer and fastening the microphone holder to a stand or the like. base
2. The sound field measuring device according to claim 1, wherein a multipoint microphone system constituted by the following is used. 4. The same measuring signal is individually provided for each channel to an audio reproducing apparatus comprising a plurality of channels.
Signals arranged one after another in sequence are CD, DVD,
A measurement signal recorded on a recording medium such as DAT,
2. A sound field measuring apparatus according to claim 1, further comprising means for reproducing the measurement signal. 5. A signal comprising a silent portion having a length of about 2 to 30 seconds and a signal portion in which a signal in which the same signal is repeated a plurality of times after the silent portion follows each channel in order. The sound field measuring device according to claim 1, wherein: 6. The apparatus according to claim 1, further comprising a microphone installed immediately before a speaker from which a signal is first generated, and data capturing means having a function of starting data capturing by using the signal as a trigger signal. A sound field measuring device as described. 7. A plurality of impulse signals and a plurality of time stretch pulse signals are measured from a measurement signal recorded on a recording medium such as a CD, DVD, or DAT, and a digital data sequence reproduced from the impulse signal and taken into a computer. Means for calculating the peak position of the measurement signal, means for comparing the peak position of the measurement signal with the peak position of the measurement result, and the difference between the sampling frequency of the measurement signal generator and the sampling frequency of the signal acquisition device from the difference of the peak position. A data extracting unit for correcting the sampling frequency difference and extracting the same signal portion from the measurement data sequence, an FFT processing unit for converting the extracted data into frequency characteristics,
2. The sound field measuring apparatus according to claim 1, further comprising an averaging processing unit for averaging the data. 8. A measurement signal in which a plurality of impulse signals and a plurality of time stretch pulse signals are recorded on a recording medium such as a CD, a DVD, and a DAT, and a digital data string reproduced from the impulse signal and taken into a computer. Means for extracting any two time stretch pulse portions of the measurement signal, an FFT processing portion for analyzing frequency characteristics of each of the extracted pulse portions, and a division operation for complexly dividing the two frequency data And an inverse FFT processing unit for calculating an impulse response characteristic thereafter, and a frequency difference calculating unit for calculating a difference between a sampling frequency of the signal generator and a sampling frequency of the measuring instrument from a peak position of the impulse response characteristic. The sound field measuring device according to claim 1. 9. A means for analyzing a sampling frequency difference between a player and a measuring section, a means for correcting a position from which a measurement signal is cut out using the frequency difference, and an FFT analysis of a signal cut out after position adjustment and addition. 2. The sound field measuring device according to claim 1, further comprising means for performing an averaging process. 10. A signal in which an impulse or a time stretch pulse signal is added to a front part and / or a rear part of a signal part such as a sine wave, a swept sine wave, and random noise. The described sound source for sound measurement. 11. A means for extracting a response signal of an impulse part or a time stretch pulse part provided at a start part and a tail part of a measurement signal, and an FFT processing unit for analyzing respective frequency characteristics of the extracted pulse part. A division operation unit for performing complex division on the two frequency data, an inverse FFT processing unit for calculating an impulse response characteristic thereafter, and a difference between a sampling frequency of a signal generator and a sampling frequency of a measuring instrument based on a peak position of the impulse response characteristic. 2. The sound field measuring device according to claim 1, further comprising: a frequency difference calculating unit that calculates the frequency difference.