JP2017203931A - Acoustic property measurement device and acoustic property measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure an acoustic property of a system to be measured with simple constitution, while securing measurement accuracy.SOLUTION: A sound signal output unit 720 is configured to start output of a sound signal X(t) for measurement over a predetermined time T, according to an output start instruction issued at the time when a predetermined time Telapses after starting a recording operation. While, a recording unit 730 is configured to record a sound collection result at a predetermined sound collection position of sound corresponding to the sound signal X(t) for measurement output by a sound treatment device 800 that has received the sound signal X(t) for measurement, for a period from a time point of starting the recording operation to a time point of ending an output operation. Then, a specification unit 740 is configured to specify time difference (first delay time TD) between an execution time Tof the recording operation and a sum of the predetermined time Tand the predetermined time T.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an acoustic characteristic measuring device, an acoustic characteristic measuring method, an acoustic characteristic measuring program, and a recording medium on which the acoustic characteristic measuring program is recorded.

2. Description of the Related Art Conventionally, acoustic characteristics in a predetermined space such as a passenger compartment are measured, and a sound field in the predetermined space is grasped based on the measurement result. For example, Patent Document 1 (hereinafter referred to as “conventional example”) discloses a technique for performing the following (i) and (ii).
(I) While measuring the acoustic characteristics of a space (for example, a concert hall) having a target acoustic effect, the acoustic characteristics in the passenger compartment are measured.
(Ii) Using both of the measured acoustic characteristics, the acoustic effect of the target space is reproduced in the passenger compartment.

  In this conventional technique, when measuring the acoustic characteristics in the vehicle interior, the sound transmitted from the speaker disposed in the vehicle interior and propagating through the vehicle interior is recorded using a microphone disposed at a predetermined position. . Then, it is described that a transfer function of a measured system determined by a pair of a sound output position that is a speaker placement position and a sound pickup position that is a microphone placement position is calculated as an acoustic characteristic of the measured system. Yes.

  Such acoustic characteristic measurement utilizes the fact that a sound pickup signal from a microphone is a result of convolution integration between an output sound signal from a speaker and an impulse response of a system under measurement. That is, in the conventional technique, an impulse response is calculated based on a sound collection signal when an impulse signal or the like is used as an output sound signal. Subsequently, the transfer function obtained by Fourier transforming the impulse response is obtained as the acoustic characteristics of the system to be measured.

JP 2011-216989 A

  The conventional technology described above is based on the premise that it is possible to grasp the synchronous relationship between the sound output from the speaker of the sound processing device that supplies sound to the system to be measured and the recording of the sound collection result by the microphone when measuring the acoustic characteristics. ing. In the conventional technique, if the synchronization relationship cannot be grasped, an unpredictable time relationship between the transfer function measured as an acoustic characteristic and the true transfer function for each system to be measured is measured. An error in element characteristics (for example, phase characteristics) occurs.

  For this reason, in order to measure the acoustic characteristics of the system to be measured by the technique of the conventional example, it is necessary to have a configuration capable of grasping the synchronization relationship between the sound output to the system to be measured and the recording. As a configuration that satisfies this requirement, a system configuration in which a measurement device having a recording function supplies a sound signal for measurement to a sound processing device, and a sound processing device that has received the measurement sound signal promptly supplies sound to a system to be measured. Can be considered.

  As a standard portable device having a recording function for recording one system, a sound signal output function, and an arithmetic processing function, for example, a smartphone or the like is widely used. Use of such a standard portable device is convenient because the sound collection position can be easily changed. Then, in the standard portable device, it seems that the above-described system configuration can be easily realized by executing an application program for performing measurement sound signal output operation and recording function operation.

  However, according to the knowledge obtained as a result of research and development by the inventor of the present application, in a standard portable device, until the sound output is actually performed from the start of the sound output operation start step by the application program, In view of the accuracy of the acoustic characteristics normally required, there is a delay time that cannot be ignored. Depending on the model of the portable device, the delay time exhibits a variation that cannot be ignored in view of the accuracy of the acoustic characteristics that are normally required.

  In the conventional technique, a signal indicating the start of sound output to the system to be measured is supplied to the measurement apparatus, and the sound output to the system to be measured is synchronized with the recording by feeding back the sound output start to the measurement apparatus. It can be set as the system configuration which can grasp | ascertain a relationship. However, using a standard portable device such as a smartphone cannot provide feedback for starting sound output, and thus cannot be configured as described above. For this reason, it cannot be said that the above-described system configuration can be easily realized by using a standard portable device.

  For this reason, there is a demand for a technique that can be easily measured while ensuring the measurement accuracy of the acoustic characteristics of the system to be measured. Responding to such a request is cited as one of the problems to be solved by the present invention.

  The invention according to claim 1 is a sound signal output unit that outputs a measurement sound signal over a second time in response to an output start command issued after the first time has elapsed since the start of the recording operation; From the start time of the recording operation to the end time of the output operation of the measurement sound signal, the sound corresponding to the measurement sound signal output by the sound processing device that has received the measurement sound signal is collected at a predetermined sound pickup position. A recording unit for recording including the collected sound results; and a specifying unit for specifying a time difference between an execution time of the recording operation and a sum of the first time and the second time. It is an acoustic characteristic measuring device.

  The invention according to claim 8 is an acoustic characteristic measuring method used in an acoustic characteristic measuring apparatus including a sound signal output unit, a recording unit, and a specifying unit, wherein the sound signal output unit performs a recording operation. A sound signal output step of outputting a measurement sound signal over a second time in response to an output start command issued after a lapse of the first time from the start; and the recording unit from the start of the recording operation Including the sound collection result obtained by collecting the sound corresponding to the measurement sound signal output by the sound processing apparatus that has received the measurement sound signal at a predetermined sound collection position until the end of the output operation of the measurement sound signal An acoustic characteristic comprising: a recording step of recording; and a specifying step of specifying the time difference between the execution time of the recording operation and the sum of the first time and the second time. This is a measurement method.

  The invention described in claim 9 is an acoustic characteristic measurement program that causes a computer included in the acoustic characteristic measurement device to execute the acoustic characteristic measurement method according to claim 8.

  According to a tenth aspect of the present invention, there is provided a recording medium in which the acoustic characteristic measuring program according to the ninth aspect is recorded so as to be readable by a computer included in the acoustic characteristic measuring apparatus.

1 is a block diagram illustrating a schematic configuration of an acoustic characteristic measurement device according to an embodiment of the present invention. It is a figure for demonstrating the timing of the sound signal for measurement X (t) at the time of the acoustic characteristic measurement of a to-be-measured system, and the recording signal Y (t). It is a figure for demonstrating the timing of the sound signal for measurement X (t) at the time of the measurement for calibration, and the sound recording signal Y (t). 1 is a block diagram illustrating a schematic configuration of an acoustic characteristic measuring apparatus according to an embodiment of the present invention. It is a figure for demonstrating the content of the to-be-measured system information of FIG. It is a figure for demonstrating the content of the sound data for a measurement of FIG. 4, acoustic characteristic information, and delay time information. It is a flowchart for demonstrating the measurement process for calibration. It is a flowchart for demonstrating an acoustic characteristic measurement process. FIG. 9 is a flowchart for explaining an impulse response calculation process of FIG. 8. FIG. It is a figure which shows the example of a display of the still image of an impulse response, sound pressure distribution, and phase difference distribution. It is a figure which shows the example of a display of the moving image of a wavefront movement.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In the following description and drawings, the same or equivalent elements are denoted by the same reference numerals, and redundant description is omitted.

[Constitution]
FIG. 1 shows a schematic configuration of an acoustic characteristic measuring apparatus 700 according to an embodiment. As shown in FIG. 1, the acoustic characteristic measuring apparatus 700 collects sound output from the speaker SP of the sound processing apparatus 800 disposed outside the acoustic characteristic measuring apparatus 700.

  In the present embodiment, the sound processing device 800 receives the measurement sound signal X (t) that is an electrical signal output from the acoustic characteristic measurement device 700 and is an analog signal. Then, volume processing is performed on the measurement sound signal X (t), and the volume-adjusted sound is output from the speaker SP. In the present embodiment, the number of speakers SP is one.

  The sound processing apparatus 800 according to the present embodiment having such a function includes an AD (Analogue to Digital) conversion unit, a sound processing unit, and a DA (Digital to Analogue) conversion unit in addition to the speaker SP described above. . In the sound processing device 800, the AD conversion unit receives the measurement sound signal X (t) via the wired wiring, and converts the measurement sound signal X (t) into a digital sound signal. Subsequently, the sound processing unit performs sound processing such as volume processing on the digital audio signal to generate a digital output sound signal.

  Next, the DA converter converts the digital output sound signal into an analog output sound signal. Then, the speaker SP outputs a sound corresponding to the analog output sound signal.

  As the sound processing device 800, for example, a sound processing device arranged in a concert hall, a vehicle, or the like that can switch the input sound signal to the measurement sound signal X (t) can be employed.

  The acoustic characteristic measuring apparatus 700 includes a storage unit 710, a sound signal output unit 720, and a recording unit 730. The acoustic characteristic measuring apparatus 700 includes a specifying unit 740, a calibration unit 750, an analysis unit 760, and a display unit 770.

  Various information is recorded in the storage unit 710. Such information includes measured system information, measurement sound data, recording data, acoustic characteristic information, and delay time information.

  The measured system information includes a sound output position and a sound collection position for each of the plurality of measured systems. Here, when the number of speakers arranged at the fixed position is one, the sound output positions in all of the measured systems are the same.

  The system to be measured is determined by a pair of a sound output position (arrangement position of the speaker SP that outputs sound) and a sound collection position (arrangement position of the microphone MC).

  In this embodiment, two types of sound data for measurement are prepared, ie, first measurement sound data for measuring the acoustic characteristics of the measurement target system and second measurement sound data (sound source data) for calibration measurement. Has been. Here, the first measurement sound data is random sound data created using uniform random numbers, Gaussian random numbers, or the like. The second measurement sound data is sound data in which the amplitude value rises early after the start of sound output.

Both the first and second measurement sound data are sound data obtained by sampling at a predetermined sampling frequency f _S (for example, 44.1 kHz).

  The recording data includes the data of the recording result by the recording unit 730. The acoustic characteristic information includes acoustic characteristic information for each measured system. In the present embodiment, the acoustic characteristic information is an impulse response.

  The delay time information includes a first delay time and a second delay time. The first delay time and the second delay time will be described later.

  The sound signal output unit 720 includes a DA (Digital to Analogue) conversion unit. The sound signal output unit 720 sequentially reads the designated measurement sound data from the storage unit 710 when an output start command is made in which the measurement sound data and the output time are designated. Subsequently, the sound signal output unit 720 generates a measurement sound signal X (t) that is an analog sound signal by performing DA conversion on the sequentially read data by the DA conversion unit. The measurement sound signal X (t) generated in this way is sent to the sound processing device 800. Then, when the designated output time has elapsed from the start of output of the measurement sound signal X (t), the sound signal output unit 720 stops outputting the measurement sound signal X (t).

The sound signal output unit 720 performs initial buffering processing of the measurement sound data read from the storage unit 710 in order to generate the measurement sound signal X (t) that faithfully reflects the designated measurement sound data. After that, DA conversion is sequentially performed on the buffered data at the sampling frequency f _S , and generation of the measurement sound signal X (t) is started. For this reason, a delay of the first delay time TD ₁ occurs from when the output start command is issued to when the measurement sound signal X (t) starts to be output.

The recording unit 730 includes a single microphone MC and an AD (Analogue to Digital) conversion unit. The recording unit 730 starts a recording operation when a recording start command is issued. When such a recording operation is started, the amplitude value of the sound collected by the microphone MC is sampled at the sample frequency f _S and converted into a digital value. A sequence of individual sound data obtained as a result of this conversion is sent to the storage unit 710 as a recording signal Y (t) and stored as recording data. Then, when the output of the measurement sound signal X (t) from the sound signal output unit 720 stops, the recording unit 730 stops the recording operation.

When the recording operation by the recording unit 730 stops, the specifying unit 740 performs the above-described specifying process of the first delay time TD ₁ . Then, the identified first delay time TD ₁ is stored in the delay time information in the storage unit 710.

Note that the specifying process of the first delay time TD ₁ executed by the specifying unit 740 will be described later.

The calibration unit 750 performs the specifying process of the second delay time TD ₂ based on the second measurement sound data in the storage unit 710, the recording data at the time of calibration measurement, and the first delay time information TD _1. Thus, the delay characteristic of the sound processing device 800 is detected. Then, the specified second delay time TD ₂ is stored in the delay time information in the storage unit 710.

The specifying process of the second delay time TD ₂ executed by the calibration unit 750 will be described later.

The above analysis unit 760, first measuring sound data in the storage unit 710, the recording data in each of the measurement system, the first based on the delay time TD ₁ and the second delay time TD _2, each of the measured system The impulse response calculation process is performed. The impulse responses of the measured system thus calculated are stored in the acoustic characteristic information in the storage unit 710.

  In addition, when an impulse response display processing command designating the system to be measured is issued, the analysis unit 760 generates display data of the impulse response of the designated system to be measured in the acoustic characteristic information in the storage unit 710. The display data generated in this way is sent to the display unit 770.

  Further, when a display processing command in which the display image type and the target frequency are specified is made, the analysis unit 760 is specified based on each impulse response of the measured system in the acoustic characteristic information in the storage unit 710. Display data for displaying the display image type is generated. The display data generated in this way is sent to the display unit 770.

  In the present embodiment, the designated image types include a sound pressure distribution image, a phase difference distribution image, and a moving image of wavefront movement.

  The impulse response calculation processing and display processing executed by the analysis unit 760 will be described later.

  The display unit 770 includes a display device such as a liquid crystal display device. Display unit 770 receives display data sent from analysis unit 760. Then, the display unit 770 displays an image corresponding to the display data.

  Here, the timing relationship between the measurement sound signal X (t) and the recording signal Y (t) at the time of measurement by the combination of the acoustic characteristic measuring apparatus 700 and the sound processing apparatus 800 configured as described above will be described.

<Timing relationship when measuring acoustic characteristics>
At the time of measuring the acoustic characteristics, the microphone MC of the acoustic characteristic measuring apparatus 700 is disposed at the sound collection position for measuring the acoustic characteristics. A general timing relationship between the measurement sound signal X (t) and the recording signal Y (t) in this case is shown in FIG.

When measuring the acoustic characteristics, as shown in FIG. 2, a recording start command is issued at an arbitrary time t ₀ . Thereafter, the output start command is issued at time t ₁ (= t ₀ + T ₁ ) when the predetermined time (first time) T ₁ has passed without the output start command being issued. As a result, at time t ₂ from time t ₁ a first delay time TD ₁ has elapsed (= t ₁ + TD _1), the output of the measuring sound signals X from the sound signal output section 720 (t) is started. Then, a predetermined time (second time) from the time t ₂ is a measuring sound output time at time t ₅ to T ₂ has elapsed (= t ₂ + D _2), the measuring sound signal from the sound signal output section 720 X ( The output of t) stops.

When the above output operation of the measuring sound signal X (t) is performed, the time t ₃ when the second delay time TD ₂ is a volume processing time in the sound processor 800 from time t ₂ has elapsed (= t ₂ + TD ₂ ), The sound output operation from the speaker SP starts. The sound output from the speaker SP thus reaches the microphone MC after a propagation time T ₃ corresponding to the distance from the arrangement position of the speaker SP to the arrangement position of the microphone MC has elapsed. That is, sound collection of the sound output from the speaker SP by the microphone MC is started from time t ₄ (= t ₃ + T ₃ ) when the propagation time T ₃ has elapsed from time t ₃ . Then, the sound collection result by the microphone MC is converted into a digital value sequence, and the recording signal Y (t) is generated.

Thereafter, at time t ₅ , when the output operation of the measurement sound signal X (t) from the sound signal output unit 720 is stopped, the recording operation by the recording unit 730 is also stopped. For this reason, the period length of the recording operation by the recording unit 730 is a time T _REC (= (T ₁ + TD ₁ + T ₂ )) from time t ₀ to time t ₅ .

<Timing related during calibration measurement>
At the time of calibration measurement, the microphone MC of the acoustic characteristic measurement device 700 is disposed in the vicinity of the speaker SP. The timing relationship between the measurement sound signal X (t) and the recording signal Y (t) in this case is shown in FIG.

As can be seen from a comparison between FIG. 3 and FIG. 2, the above-described propagation time T ₃ can be substantially regarded as “0” during the calibration measurement. That is, time t ₃ and time t ₄ in FIG. 2 are substantially the same time. If this is excluded, the timing relationship at the time of the measurement for calibration will be the same as the timing relationship at the time of measuring the acoustic characteristics described above.

[Operation]
Next, the operation of the acoustic characteristic measuring apparatus 700 configured as described above will be described.

  It is assumed that measured system information is already registered in the storage unit 710. Further, it is assumed that the sound processing apparatus 800 is used in common for all the impulse response measurements at each of the plurality of sound collection positions.

<Measurement process for calibration>
The acoustic characteristic measuring apparatus 700 performs a calibration measurement process for specifying the second delay time TD ₂ caused by the sound processing in the sound processing apparatus 800 prior to measurement of the impulse response at each of the plurality of sound collection positions. .

  In the calibration measurement process, the microphone MC of the acoustic characteristic measurement apparatus 700 is disposed in the vicinity of the speaker SP of the sound processing apparatus 800. Subsequently, a recording start command is issued, and the recording operation by the recording unit 730 starts.

When a predetermined time T ₁ has passed since the issue of the recording start command, the second measurement sound data and an output start command specifying the predetermined time T ₂ as the output time are issued. As a result, a data string corresponding to the recording signal Y (t) whose timing relationship with the measurement sound signal X (t) is in the form shown in FIG. 3 is stored in the storage unit 710 as recording data. When a predetermined time T ₂ has elapsed from the start of output of the measurement sound signal X (t) from the sound signal output 720, the recording operation by the recording unit 730 ends.

When the recording operation is thus completed, the specifying unit 740 performs the specifying process of the first delay time TD ₁ . In the process of specifying the first delay time TD ₁ , the specifying unit 740 first determines the number N _{REC of} individual sound data constituting the recording data in the storage unit 710 obtained by the current recording operation and the sampling frequency f. Based on _S , the current recording operation time T _REC (= N _REC / f _S ) is calculated.

Subsequently, the specifying unit 740 calculates the first delay time TD ₁ in the case of the current calibration measurement based on the predetermined times T ₁ and T ₂ and the recording operation time T _REC by the following equation (1).
TD ₁ = T _REC − (T ₁ + T ₂ ) (1)
Then, the specification unit 740, a first delay time TD ₁ in the storage unit 710 is updated to the first delay time is newly calculated TD _1.

Thus, when the specifying process of the first delay time TD ₁ by the specifying unit 740 is completed, the calibration unit 750 analyzes the second measurement sound data in the storage unit 710, and first separates the second individual measurement sound data. A time ΔT _R1 from the time corresponding to the sound data to the occurrence of the first rise in the waveform corresponding to the second measurement sound data is obtained. Subsequently, when the recording start time is “0” based on the predetermined time T ₁ , the first delay time TD _1, and the time ΔT _R1 , the calibration unit 750 measures the measurement sound corresponding to the second measurement sound data. The time t _R1 when the rising edge first occurs in the signal X (t) is calculated by the following equation (2).
t _R1 = T ₁ + TD ₁ + ΔT _R1 (2)

Next, the calibration unit 750 analyzes the current recording data in the storage unit 710 and sets the recording start time to “0”. After the time (T ₁ + TD ₁ ) has elapsed from the recording start time, The time t _R2 when the rising edge first occurs in the recording signal Y (t) is obtained. Subsequently, the calibration unit 750 calculates the second delay time TD ₂ by the following equation (3) based on the time t _R1 and the time t _R2 .
TD ₂ = t _R2 −t _R1 (3)
Then, the calibration unit 750, a second delay time in the storage unit 710 TD _2, updates the newly calculated second delay time to TD _2.

<Acoustic characteristic measurement process>
When the calibration measurement described above is completed, the acoustic characteristic measuring apparatus 700 sequentially measures impulse responses at each of the plurality of sound collection positions.

  In the acoustic characteristic measurement process, the microphone MC of the acoustic characteristic measurement apparatus 700 is first placed at the first sound collection position. As a result, the first system to be measured is configured. Subsequently, after the recording start command is issued, the measurement sound signal output operation from the sound signal output unit 720 and the recording operation by the recording unit 730 are performed as in the case of the calibration measurement described above.

Subsequently, the specifying unit 740 performs the specifying process of the first delay time TD _{1 in} the same manner as in the calibration measurement described above. In this way, the new process for specifying the first delay time TD ₁ is newly performed due to a change in the internal environment of the acoustic characteristic measuring apparatus 700 at the start of the measurement sound signal output operation by the sound signal output unit 720. This is because the possibility of the delay time TD ₁ changing is taken into consideration.

Thus, when the specifying process of the new first delay time TD ₁ by the specifying unit 740 is completed, the analyzing unit 760 starts extracting the first individual sound data in the first measurement sound data in the storage unit 710 as the first data. Set to position. Subsequently, when the time corresponding to the first individual sound data in the recording data in the storage unit 710 is set to “0”, the analysis unit 760 sets the time TC calculated by the following equation (4) to the time “0”. The individual sound data at the time elapsed since is set as the second data extraction start position.
TC = T ₁ + TD ₁ + TD ₂ (4)
As a result, it is possible to accurately synchronize the input signal (that is, the sound output time from the speaker SP) related to the measurement target system to be measured and the output signal (the sound collection time by the microphone MC).

  Next, the analysis unit 760 uses the set first and second data cutout start positions to cut out individual sound data corresponding to the same time from the first measurement sound data and the recording data. Then, the analysis unit 760 calculates an impulse response of the measurement target system to be measured based on both the extracted data. Then, the analysis unit 760 stores the calculated impulse response as the impulse response of the measurement target system to be measured in the acoustic characteristic information in the storage unit 710.

  In the present embodiment, the analysis unit 760 calculates an impulse response by, for example, the cross spectrum method described in JP-A-2015-119343.

  Thus, when the measurement of the impulse response at the first sound collection position is completed, the measurement of the impulse response at the first sound collection position described above is performed while changing the arrangement position (sound collection position) of the microphone MC of the acoustic characteristic measuring apparatus 700. As in the case, the impulse response at each of the new sound pickup positions is measured. When the impulse responses for all the sound collection positions registered in the measured system information in the storage unit 710 are measured, the acoustic characteristic measurement process ends.

<Display processing>
After the acoustic characteristic measurement process is completed, the acoustic characteristic measurement apparatus 700 performs a display process according to the display command. In the present embodiment, as described above, the display processing includes impulse response display processing, sound pressure distribution display processing, phase difference distribution display processing, and wavefront movement moving image display processing.

《Impulse response display processing》
When an impulse response display command designating the system to be measured is issued, an impulse response display process is performed.

  In the display process of the impulse response, the analysis unit 760 reads the designated measured system impulse response from the storage unit 710. Subsequently, the analysis unit 760 generates display data of the impulse response based on the read impulse response. Then, the analysis unit 760 sends the generated display data to the display unit 770. As a result, an image that visualizes the impulse response of the specified system under measurement is displayed on the display unit 770.

<< Sound pressure distribution display process >>
When a sound pressure distribution display command specifying a frequency is issued, a sound pressure distribution display process is performed.

  In the sound pressure distribution display process, the analysis unit 760 reads each impulse response of the system under measurement from the storage unit 710. Subsequently, the analysis unit 760 calculates a sound pressure value at each of the sound collection positions when a sine wave of the specified frequency is output from the speaker SP based on the read impulse response and the specified frequency. To do.

  Next, the analysis unit 760 generates display data of the sound pressure distribution in the sound field space based on all the combinations of the calculated sound pressure value and the sound collection position. Then, the analysis unit 760 sends the generated display data to the display unit 770. As a result, an image that visualizes the sound pressure distribution corresponding to the designated frequency is displayed on the display unit 770.

《Phase difference distribution display processing》
When a phase difference distribution display command specifying a frequency is issued, a phase difference distribution display process is performed.

  In the display processing of the phase difference distribution, the analysis unit 760 reads each impulse response of the system under measurement from the storage unit 710. Subsequently, the analysis unit 760 calculates a phase difference at each of the sound pickup positions when a sine wave having a specified frequency is output from the speaker SP, based on the read impulse response and the specified frequency. . Here, the “phase difference” is a phase shift between positions separated by a predetermined distance.

  Next, the analysis unit 760 generates display data of the phase difference distribution in the sound field space based on all the combinations of the calculated phase difference value and the sound collection position. Then, the analysis unit 760 sends the generated display data to the display unit 770. As a result, an image obtained by visualizing the phase difference distribution corresponding to the designated frequency is displayed on the display unit 770.

《Wavefront moving image display processing》
When an instruction to display a moving image of wavefront movement designating a frequency is given, a display process of the moving image of wavefront movement is performed.

In the display processing of the moving image of the wavefront movement, the analysis unit 760 reads each impulse response of the system under measurement from the storage unit 710. Subsequently, based on the read impulse response and the designated frequency, the analysis unit 760 performs a convolution operation between the sine wave of the designated frequency and the impulse response at each of the sound collection positions to obtain the sound collection An amplitude value corresponding to the time to be displayed at each position is calculated as wavefront information.

  Next, the analysis unit 760 generates display data of a moving image of wavefront movement in the sound field space based on all the combinations of the calculated wavefront information and sound collection positions. Then, the analysis unit 760 sequentially sends the generated display data to the display unit 770 according to a predetermined display speed. As a result, a moving image in which the wavefront movement corresponding to the designated frequency is visualized is displayed on the display unit 770.

As described above, in the present embodiment, the sound signal output unit 720 performs the measurement sound over the predetermined time T ₂ according to the output start command issued after the predetermined time T ₁ has elapsed since the recording operation was started. The output of the signal X (t) is started. On the other hand, the sound for measurement output by the sound processor 800 that has received the measurement sound signal X (t) from the start of the recording operation to the end of the output operation of the measurement sound signal X (t) is recorded by the recording unit 730. A sound collection result at a predetermined sound collection position of the sound corresponding to the signal X (t) is recorded. Then, the specifying unit 740 specifies the time difference (first delay time) TD ₁ between the recording operation execution time T _REC and the sum of the predetermined time T ₁ and the predetermined time T ₂ .

For this reason, it is possible to accurately grasp the synchronization relationship between the measurement sound signal X (t) and the recording signal Y (t) by taking into account the time difference TD ₁ in the acoustic specific measurement of the system under measurement.

In the present embodiment, the calibration unit 750 records the recording result when the position near the sound output position of the sound processing device 800 is the calibration sound collection position, the time difference identified by the identification unit 740, and the measurement sound Based on the sound source data of the signal, the delay characteristic (second delay time TD ₂ ) of the sound processing device 800 is detected. For this reason, in the acoustic specific measurement of the system under measurement, the measurement sound signal X (t) and the recording are taken into consideration by considering the delay characteristic of the sound processing device 800 in addition to the time difference TD ₁ specified by the specifying unit 740. The synchronization relationship with the signal Y (t) can be grasped very accurately.

  In the above-described embodiment, the analysis unit 760 performs sound recording based on the recording result of the sound collection result at the predetermined sound collection position, the time difference identified by the identification unit 740, and the delay characteristic detected by the calibration unit 750. The acoustic characteristics of the system under measurement determined by the combination of the sound output position of the processing device 800 and the predetermined sound collection position are analyzed. For this reason, it can measure simply, ensuring the measurement precision of the acoustic characteristic of a to-be-measured system.

  In the present embodiment, the display unit 770 displays the analysis result by the analysis unit 760. For this reason, the measurement result of the acoustic characteristics of the system under measurement can be visualized.

  Moreover, in this embodiment, the analysis part 760 analyzes the acoustic characteristic for every several to-be-measured system from which a sound collection position mutually differs. Then, a still image of sound pressure distribution, a still image of phase distribution, and a moving image of wavefront movement obtained based on the measured acoustic characteristics for each system to be measured are displayed on display unit 770. For this reason, the characteristics of the sound field can be visualized.

<Modification of Embodiment>
Various modifications can be made to the above embodiment.

  For example, in the above embodiment, the impulse response, which is the time characteristic, is measured as the acoustic characteristic. On the other hand, in addition to the impulse response, at least one of the frequency characteristic and the phase characteristic may be measured.

  In the above embodiment, the number of speakers included in the sound processing device is “1”, but the number of speakers included in the sound processing device may be “2 or more”. And it is good also considering the number of the speakers which output a sound in the case of an acoustic characteristic measurement as multiple.

In the above embodiment, the sound processing apparatus is common in measuring the acoustic characteristics of all the systems to be measured. On the other hand, when a different sound processing device is used, detection of the delay characteristic of the sound processing device, that is, identification processing of the second delay time TD ₂ may be performed every time the sound processing device is changed. .

  In the above embodiment, different measurement sound data are used for the calibration measurement and the acoustic characteristic measurement. On the other hand, random sound data may be used for both the calibration measurement and the acoustic characteristic measurement.

In the above embodiment, the second measurement sound data in the storage unit 710 is analyzed during the calibration measurement, and the time ΔT _R1 is obtained. In contrast, previously obtained in advance the analysis to the time [Delta] T _R1 a second measuring sound data, may be stored a time [Delta] T _R1 obtained in advance in the storage unit 710.

  In the above embodiment, the impulse response is calculated by the cross spectrum method. On the other hand, the impulse response may be calculated by another method.

  Note that a computer as a calculation unit including a central processing unit (CPU) or the like for a part or all of the specifying unit 740, the calibration unit 750, and the analysis unit 760 of the acoustic characteristic measuring apparatus 700 of the above embodiment. And a part of or all of the functions of the specifying unit 740, the calibration unit 750, and the analysis unit 760 may be performed by executing a program prepared in advance on the computer. This program is recorded on a computer-readable recording medium such as a hard disk, CD-ROM, or DVD, and is loaded from the recording medium and executed by the computer. The program may be acquired in a form recorded on a portable recording medium such as a CD-ROM or DVD, or may be acquired in a distribution form via a network such as the Internet. Also good.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. In the following description and drawings, the same or equivalent elements including the above-described embodiment are denoted by the same reference numerals, and redundant description is omitted.
[Constitution]
FIG. 4 shows a schematic configuration of an acoustic characteristic measuring apparatus 100 according to an embodiment. The acoustic characteristic measuring apparatus 100 is an aspect of the acoustic characteristic measuring apparatus 700 (see FIG. 1) of the above-described embodiment.

  As shown in FIG. 4, sound output from the speaker SP of the sound processing device 200 arranged outside the acoustic characteristic measuring device 100 is recorded. The number of speakers in the sound processing device 200 is set to one as in the case of the sound processing device 800 described above. In addition, the arrangement position of the speaker SP in the sound processing apparatus 200 is a fixed position as in the sound processing apparatus 800. That is, the sound processing apparatus 200 in the present example fulfills the function of the sound processing apparatus 800 in the above-described embodiment.

  The acoustic characteristic measuring apparatus 100 includes a processing control unit 110, a storage unit 120, and an input unit 130. In addition, the acoustic characteristic measuring apparatus 100 includes a display unit 140, a signal output unit 150, a sound collection unit 160, and a wireless communication unit 170.

  The processing control unit 110 performs overall control of the entire acoustic characteristic measuring apparatus 100 and performs various processes. The processing control unit 110 will be described later.

  The storage unit 120 includes a nonvolatile storage element, and stores various information data used in the acoustic characteristic measurement apparatus 100. Such information data includes measured system information MCI, measurement sound data MSD, recording data RCD, acoustic characteristic information SCI, and delay time information DTI. That is, the storage unit 120 performs the function of the storage unit 710 in the above-described embodiment.

  The contents of measured system information MCI, measurement sound data MSD, recording data RCD, acoustic characteristic information SCI, and delay time information DTI stored in the storage unit 120 will be described later.

  The input unit 130 includes a key unit provided in the main body of the acoustic characteristic measuring apparatus 100 and / or a remote input device including the key unit. Here, as a key part provided in the main body part, a touch panel provided in a display device of the display unit 140 can be used. In addition, it can replace with the structure which has a key part, or can also employ | adopt the structure input with a sound using a voice recognition technique in combination.

  When the user operates the input unit 130, the processing content of the acoustic characteristic measuring apparatus 100 is designated. Such designation includes the designation of the start of calibration measurement processing by the process control unit 110, the designation of the start of acoustic characteristic measurement, the designation of display for each type of display image, and the like.

  The display unit 140 receives display data sent from the processing control unit 110. Then, the display unit 140 displays an image corresponding to the display data. The images displayed on the display unit 140 in this way include impulse responses measured as acoustic characteristics for each system under measurement, and sound pressure distribution, phase difference distribution, and wavefront moving images in the sound field space. . In other words, the display unit 140 performs the function of the display unit 770 in the above-described embodiment.

The signal output unit 150 includes a DA conversion unit. The signal output unit 150 receives individual sound data periodically sent from the processing control unit 110 at the sampling frequency f _S. Then, the signal output unit 150 performs DA conversion on the individual sound data. The result of such DA conversion is transmitted to the sound processing apparatus 200 as a measurement sound signal X (t). In other words, the signal output unit 150 performs a part of the function of the sound signal output unit 720 in the above-described embodiment.

The sound collection unit 160 includes one microphone MC and an AD conversion unit. In the sound collection unit 160, when the recording operation start is designated by the processing control unit 110, the sound collection operation is started. During the recording process, the sound collection unit 160 samples the amplitude of the sound collected by the microphone MC at the sampling frequency f _S until the recording operation stop is designated by the processing control unit 110, and the digital value is digitally converted by the AD conversion unit. Converted to a value. A data string obtained as a result of this conversion is sent to the processing control unit 110 as recorded data representing the recorded signal Y (t). That is, the sound collection unit 160 performs a part of the function of the recording unit 730 in the above-described embodiment.

  The wireless communication unit 170 communicates with an external device that uses acoustic characteristic information under the control of the processing control unit 110. By using the wireless communication unit 170, the processing control unit 110 receives new measurement condition information from the external device, and transmits the measurement result of the acoustic characteristics to the external device.

  Next, the processing control unit 110 will be described. The processing control unit 110 includes a central processing unit (CPU) and peripheral circuits (including a timing mechanism). Various functions as the acoustic characteristic measuring apparatus 100 are realized by the processing control unit 110 executing various programs. These functions include the functions of a part of the sound signal output unit 720, a part of the recording unit 730, the specifying unit 740, the calibration unit 750, and the analysis unit 760 in the above-described embodiment.

  In addition, the processing control unit 110 uses the wireless communication unit 170 to receive measurement condition information for new acoustic characteristic measurement from the outside. Then, the processing control unit 110 stores the newly received measured system information in the storage unit 120 as measured system information MCI.

  Further, the processing control unit 110 performs calibration measurement processing and acoustic characteristic measurement processing. Further, the processing control unit 110 performs an image display control process for visualizing the acoustic characteristics.

  Further, the processing control unit 110 uses the wireless communication unit 170 to transmit the acoustic characteristic measurement result to an external device.

  The program executed by the processing control unit 110 is recorded on a computer-readable recording medium such as a hard disk, CD-ROM, or DVD, and is loaded from the recording medium and executed. The program may be acquired in a form recorded on a portable recording medium such as a CD-ROM or DVD, or may be acquired in a distribution form via a network such as the Internet. Also good.

  Here, the contents of measured system information MCI, measurement sound data MSD, recording data RCD, acoustic characteristic information SCI, and delay time information DTI stored in the storage unit 120 will be described.

<Measured system information MCI>
In this embodiment, a plurality of measured systems are set as shown in FIG. That is, in this embodiment, the sound output position PS of the speaker SP is fixed, and the lattice points of the two-dimensional square lattice with the lattice interval L are set to the sound collection positions PM _{i, j} (i = 1 to M, j = 1 to N). ) Is set.

In accordance with the settings of the plurality of measured systems, as shown in FIG. 5B, the measured system information MCI indicates the sound output position PS _{i, j} and the collected sound in the measured system # (i, j). The position PM _{i, j} and the grid interval L are included. In this embodiment, since the sound output position PS of the speaker SP is fixed as described above, all the sound output positions PS _{i, j} are the positions PS.

  Note that the frequency of the sound that can appropriately display the sound pressure distribution, the phase difference distribution, and the moving image of wavefront movement in the sound field space is determined by the lattice interval L. From this viewpoint, it is preferable that the lattice spacing L is (1/2) or more of the wavelength.

<Measurement sound data MSD>
In the present embodiment, as shown in FIG. 6A, the measurement sound data MSD includes first measurement sound data and second measurement sound data. Here, the first measurement sound data is random sound data created using uniform random numbers, Gaussian random numbers, or the like. The second measurement sound data is sound data in which the amplitude value rises early after the start of sound output.

<Recording data RCD>
The recording data RCD is stored in the order in which the individual sound data sent from the sound collection unit 160 is sent from the sound collection unit 160.

<Acoustic characteristic information SCI>
In the present embodiment, as shown in FIG. 6B, the acoustic characteristic information SCI includes an impulse response h _ij (t) that is acoustic characteristic information for each measured system # (i, j). Yes.

<Delay time information DTI>
In the present embodiment, as shown in FIG. 6C, a first delay time TD ₁ and a second delay time TD ₂ are included.

[Operation]
Next, the operation of the acoustic characteristic measuring apparatus 100 configured as described above will be described mainly focusing on the calibration measurement process, the acoustic characteristic measurement process, and the display control process performed by the processing control unit 110. It is assumed that the information on the system under measurement whose acoustic characteristics are to be measured is already stored in the storage unit 120 as the system information to be measured MCI.

<Measurement process for calibration>
Prior to the measurement of the impulse response at each of the sound collection positions PM (i, j) (that is, the system to be measured # (i, j)), the processing control unit 110 performs the first processing caused by the sound processing in the sound processing apparatus 200. The measurement process for calibration for specifying the two delay times TD ₂ is performed.

  In the calibration measurement process, the microphone MC is disposed in the vicinity of the speaker SP of the sound processing apparatus 200. Subsequently, when a calibration measurement is input to the input unit 130, the process control unit 110 executes a calibration measurement process.

  In the calibration measurement process, as shown in FIG. 7, in step S11, the process control unit 110 issues a recording start command for starting a recording routine. As a result, the recording operation starts. Note that the recording routine starts the recording process as soon as a recording start command is issued.

Next, in step S12, the processing control unit 110, whether or not a predetermined time T ₁ from the start of the recording operation has elapsed. If the result of the determination in step S12 is negative (step S12: N), the process of step S12 is repeated.

Elapsed from the start of the recording operation a predetermined time T ₁ is, when the result of determination in step S12 is affirmative (step S12: Y), the process proceeds to step S13. In step S13, the processing control unit 110, to start the signal output routine, the second measuring sound data, and issues an output start instruction specifying a predetermined time T ₂ as output time.

The signal output routine performs an initial buffering process of the measurement sound data read from the storage unit 120 in order to generate the measurement sound signal X (t) that faithfully reflects the designated measurement sound data. After doing so, the buffered data is sequentially sent to the signal output unit 150. Upon receiving the data sent from the processing control unit 110 in this way, the signal output unit 150 sequentially performs DA conversion on the data at the sampling frequency f _S and outputs it as a measurement sound signal X (t). For this reason, a delay of the first delay time TD ₁ occurs from when the output start command is issued until the output of the measurement sound signal X (t) generated by the signal output unit 150 starts.

Next, in step S < _b > 14, the processing control unit 110 determines whether or not a predetermined time T ₂ has elapsed from the start of output by the signal output unit 150. If the result of the determination in step S14 is negative (step S14: N), the process of step S14 is repeated. As a result, a data string corresponding to the recording signal Y (t) in which the timing relationship with respect to the measurement sound signal X (t) is in the form shown in FIG. 3 is stored in the storage unit 120 as recording data. .

Passed from the output start by the signal output unit 150 the predetermined time T ₂ is, when the result of determination in step S14 is affirmative (step S14: Y), the process proceeds to step S15. In step S15, the processing control unit 110 stops the output operation from the signal output unit 150 and the recording operation for recording the sound collection result by the sound collection unit 160. Note that the output operation from the signal output unit 150 and the recording operation for recording the sound collection result by the sound collection unit 160 are finished immediately after the stop process by the processing control unit 110 is executed.

Next, in step S <b> 16, the process control unit 110 performs a specific process for the first delay time TD ₁ . In the process of specifying the first delay time TD ₁ , the processing control unit 110 first counts the number N _{REC of} individual sound data constituting the recording data in the storage unit 120 obtained by the current recording operation and the sampling frequency. Based on f _S , the current recording operation time T _REC (= N _REC / f _S ) is calculated.

Subsequently, the processing control unit 110 calculates the first delay time TD ₁ in the case of the current calibration measurement based on the predetermined times T ₁ and T ₂ and the recording operation time T _REC by the above-described equation (1). . Then, the processing control unit 110, a first delay time TD ₁ storage unit 120, and updates the first delay time is newly calculated TD _1.

Next, in step S17, the processing control unit 110 analyzes the second measurement sound data in the storage unit 120 and starts the second measurement sound from the time corresponding to the first individual sound data in the second measurement sound data. The time ΔT _R1 until the first rise in the waveform corresponding to the sound data occurs is obtained. Subsequently, the processing control unit 110 performs measurement corresponding to the second measurement sound data when the recording start time is set to “0” based on the predetermined time T ₁ , the first delay time TD ₁ and the time ΔT _R1 . The time t _R1 when the rising edge first occurs in the sound signal X (t) is calculated by the above-described equation (2).

Next, in step S18, when the processing control unit 110 analyzes the current recording data in the storage unit 120 and sets the recording start time to “0”, the time (T ₁ + TD ₁ ) from the recording start time. After time elapses, a time t _R2 at which the rising edge first occurs in the recording signal Y (t) is obtained.

Then, in step S19, the processing control unit 110, based on the time t _R1 and time t _R2, the second delay time TD _2, by calculating the above equation (3), the delay characteristic of the sound processing apparatus 200 Is detected. Then, the processing control unit 110, a second delay time storage unit 120 TD _2, updates new second delay time TD ₂ calculated. Thereafter, the calibration measurement process ends.

<Acoustic characteristic measurement process>
When the above-described calibration measurement is completed, the processing control unit 110 executes the acoustic characteristic measurement process by sequentially performing the individual acoustic characteristic measurement process that is an impulse response measurement process at each of the sound collection positions # (i, j). To do.

  In the acoustic characteristic measurement process, the microphone MC of the acoustic characteristic measurement apparatus 100 is first placed at the first sound collection position. As a result, the first system to be measured is configured. Thereafter, an individual acoustic characteristic measurement process for the first system to be measured is performed.

  In the individual acoustic characteristic measurement process, as shown in FIG. 8, first, in step S21, the process control unit 110 issues a recording start command for starting a recording routine, as in step S11 described above. . As a result, the recording operation starts.

Next, in step S22, the processing control unit 110, as in the case of step S12 mentioned above, whether or not a predetermined from the start of the recording operation time T ₁ is passed. If the result of the determination in step S22 is negative (step S22: N), the process of step S22 is repeated.

Elapsed from the start of the recording operation a predetermined time T ₁ is, when the result of determination in step S22 is affirmative (step S22: Y), the process proceeds to step S23. In step S23, the processing control unit 110, to start the signal output routine, first the measuring sound data, and issues an output start instruction specifying a predetermined time T ₂ as output time.

Then, in step S24, the processing control unit 110, in the same manner as in the step S14 described above, whether or not a predetermined time T ₂ from the output initiation by the signal output unit 150 has elapsed. If the result of the determination in step S24 is negative (step S24: N), the process of step S24 is repeated.

Passed from the output start by the signal output unit 150 the predetermined time T ₂ is, when the result of determination in step S24 is affirmative (step S24: Y), the process proceeds to step S25. In step S25, the processing control unit 110 stops the output operation from the signal output unit 150 and the recording operation for recording the sound collection result by the sound collection unit 160.

  Next, in step S26, the process control unit 110 performs an impulse response calculation process for the target measurement system. Then, when the process of step S26 ends, the individual acoustic characteristic measurement process ends. Details of the impulse response calculation process in step S26 will be described later.

  Thus, when the measurement of the impulse response of the first system under test is completed, the individual acoustic characteristic measurement process described above is executed while changing the arrangement position (sound collecting position) of the microphone MC. When the impulse responses for all the sound collection positions registered in the measured system information MCI in the storage unit 120 are measured, the acoustic characteristic measurement process ends.

《Impulse response calculation processing》
Next, the impulse response calculation process in step S26 described above will be described.

In this embodiment, the impulse response is calculated by the cross spectrum method. Further, in this embodiment, when using the cross spectrum method, the number of data to be subjected to one Fourier transform is “P (for example, 2048)” and corresponds to the “P” data in the recorded data. Fourier transform is performed for the time interval to be performed. Then, based on the cumulative addition value of the power spectral density and the cumulative addition value of the cross spectral density for “Q (for example, 64)” time intervals (section length = P × f _s ) that are continuous in time. The impulse response is calculated.

In the impulse response calculation process, as shown in FIG. 9, first, in step S31, the process control unit 110 performs the first delay time TD ₁ specifying process in the same manner as in step S16 described above. Do. Then, the processing control unit 110, a first delay time TD ₁ storage unit 120, and updates the first delay time is newly calculated TD _1. Thus, the new specific processing of the first delay time TD ₁ is performed because the first delay time is changed due to the change in the internal state of the processing control unit 110 at the start of the measurement sound signal output operation by the signal output unit 150. This is because the possibility of changing TD ₁ is taken into consideration.

  Next, in step S32, the process control unit 110 sets the parameter q to “0”. Subsequently, in step S33, the processing control unit 110 sets the initial value at each frequency of the accumulated value of the power spectral density to “0” and sets the initial value at each frequency of the cross spectral density to “0”.

Next, in step S34, the processing control unit 110 _sets the cutout start position PC _q1 of the first measurement sound data corresponding to the current value of the parameter q, and the position of the first individual sound data of the first measurement sound data as “ It is calculated by the following equation (5) as “0”.
PC _q1 = P × q (5)

Subsequently, in step S35, the processing control unit 110 _sets the recording data extraction start position PC _q2 corresponding to the current value of the parameter q to “0” as the position of the first individual sound data of the first measurement sound data. It calculates with the following (6) Formula.
PC _q2 = (T ₁ + TD ₁ + TD ₂ ) × f _S + P × q (6)

Next, in step S36, the processing control unit 110 cuts out P pieces of individual sound data in the first measurement sound data for the first time from the cut start position PC _{q1 of} the first measurement sound data. And after calculating a power spectrum density using the result of having performed the Fourier transform with respect to the time waveform corresponding to the cut-out data, the cumulative addition value of a power spectrum density is calculated.

Subsequently, the processing control unit 110 cuts out P pieces of individual sound data in the recorded data for the first time from the cut-out start position PC _{q2 of} the recorded data. Then, the cross spectrum density is calculated using the result obtained by performing Fourier transform on the time waveform corresponding to the cut out data, and then the cumulative addition value of the cross spectrum density is calculated.

  Next, in step S37, the processing control unit 110 determines whether or not the value of the parameter q is “Q−1”. If the result of the determination in step S37 is negative (step S37: N), the process proceeds to step S38.

  In step S38, the parameter q is incremented (q ← (q + 1)). Thereafter, the process returns to step S34. Thereafter, the processes in steps S34 to S38 are repeated until the result of the determination in step S37 becomes affirmative.

If the value of parameter q is “Q−1” and the result of determination in step S37 is affirmative (step S37: Y), the process proceeds to step S39. In step S39, the processing control unit 110, based on the cumulative addition value of the power spectral density and the cumulative addition value of the cross spectral density at that time, the impulse response of the system under test # (i, j) that is the measurement target. Calculate _{hi, j} (t). Then, the process control unit 110 stores the calculated impulse response h _{i, j} (t) in the storage unit 120.

  When the process of step S39 is completed in this way, the process of step S26 is completed. Then, the individual acoustic characteristic measurement process ends.

<Display control processing>
Next, display processing control executed by the processing control unit 110 will be described.

《Impulse response display control processing》
When an impulse response display designation designating the system to be measured is input to the input unit 130, the processing control unit 110 performs an impulse response display control process.

  In such impulse response display control processing, the processing control unit 110 reads the impulse response of the specified system under measurement from the storage unit 120. Subsequently, the processing control unit 110 generates display data of the impulse response based on the read impulse response. Then, the process control unit 110 sends the generated display data to the display unit 140. As a result, an image that visualizes the impulse response of the designated system to be measured is displayed on the display unit 140.

  An example of an image in which the impulse response is visualized is shown in FIG.

<< Sound pressure distribution display process >>
When a sound pressure distribution display designation specifying a frequency is input to the input unit 130, the processing control unit 110 performs a sound pressure distribution display control process.

  In the sound pressure distribution display control processing, the processing control unit 110 reads each impulse response of the system under measurement from the storage unit 120. Subsequently, the processing control unit 110 calculates the sound pressure value at each of the sound collection positions when a sine wave of the specified frequency is output from the speaker SP based on the read impulse response and the specified frequency. calculate.

  Next, the processing control unit 110 generates display data of the sound pressure distribution in the sound field space based on all the combinations of the calculated sound pressure value and the sound collection position. In generating the display data, in this embodiment, the processing control unit 110 performs linear interpolation based on the sound pressure value calculated for each sound collection position, and then normalizes the calculated sound pressure value based on the maximum value. I do. Then, display data is generated by assigning brightness or color to each normalized sound pressure value.

  Then, the processing control unit 110 sends the generated display data to the display unit 140. As a result, an image obtained by visualizing the sound pressure distribution corresponding to the designated frequency is displayed on the display unit 140.

  An example of an image in which the sound pressure distribution is visualized is shown in FIG.

《Phase difference distribution display processing》
When the display specification of the phase difference distribution specifying the frequency is input to the input unit 130, the processing control unit 110 performs the display control processing of the phase difference distribution.

  In such a phase difference distribution display process, the processing control unit 110 reads each impulse response of the system under measurement from the storage unit 120. Subsequently, the processing control unit 110 calculates a phase difference at each of the sound pickup positions when a sine wave of the specified frequency is output from the speaker SP based on the read impulse response and the specified frequency. To do. Here, the “phase difference” is a phase difference between positions separated by a predetermined distance such as a distance between both ears as described above.

  Next, the processing control unit 110 generates display data of the phase difference distribution in the sound field space based on all the combinations of the calculated phase difference values and the sound collection positions. In generating the display data, in this embodiment, the processing control unit 110 performs linear interpolation based on the phase difference value calculated for each sound collection position, and then normalizes the calculated phase difference value with the maximum value. I do. Then, display data is generated by assigning luminance or color to each normalized phase difference value.

  Then, the processing control unit 110 sends the generated display data to the display unit 140. As a result, an image obtained by visualizing the phase difference distribution corresponding to the designated frequency is displayed on the display unit 140.

  An example of an image in which the phase difference distribution is visualized is shown in FIG.

《Wavefront moving image display processing》
When the display designation of the moving image of wavefront movement specifying the frequency is input to the input unit 130, the processing control unit 110 performs display control processing of the moving image of wavefront movement.

  In the display processing of the moving image of wavefront movement, the processing control unit 110 reads each impulse response of the system under measurement from the storage unit 120. Subsequently, based on the read impulse response and the designated frequency, the processing control unit 110 performs a convolution operation between the sine wave of the designated frequency and the impulse response at each of the sound collection positions, and collects the result. An amplitude value corresponding to the time to be displayed at each sound position is calculated.

  Next, the processing control unit 110 performs normalization for all the calculated amplitude values based on the maximum value among all the calculated amplitude values. Subsequently, the processing control unit 110 generates display data of an image to be displayed first. When generating such display data, the processing control unit 110 performs linear interpolation based on the normalized amplitude value. Then, display data is generated by assigning luminance or color to each value of the amplitude value subjected to linear interpolation. Then, the processing control unit 110 sends the generated display data to the display unit 140. As a result, the first image to be displayed among the moving images of wavefront movement is displayed on the display unit 140.

  Thereafter, when the display time to be displayed next is reached according to a predetermined display speed, the display data of the image to be displayed next is sequentially generated in the same manner as the display data of the image to be displayed first. Then, the generated display data is sent to the display unit 140. As a result, a moving image of wavefront movement is displayed on the display unit.

As described above, in the present embodiment, the signal output unit 150 is operated for the predetermined time T according to the output start command issued by the processing control unit 110 after the elapse of the predetermined time T ₁ after the recording operation is started. It starts outputting the measurement sound signal X (t) over _2. On the other hand, the processing control unit 110 outputs the measurement signal output from the sound processing device 200 that has received the measurement sound signal X (t) from the start time of the recording operation to the end time of the output operation of the measurement sound signal X (t). The sound collection result by the sound collection unit 160 at a predetermined sound collection position of the sound corresponding to the sound signal X (t) is recorded. Then, the processing control unit 110 specifies the time difference (first delay time) TD ₁ between the recording operation execution time T _REC and the sum of the predetermined time T ₁ and the predetermined time T ₂ .

For this reason, it is possible to accurately grasp the synchronization relationship between the measurement sound signal X (t) and the recording signal Y (t) by taking into account the time difference TD ₁ in the acoustic specific measurement of the system under measurement.

In the present embodiment, the recording control result when the processing control unit 110 uses the position near the sound output position of the sound processing apparatus 200 as the sound collection position for calibration, the specified time difference TD ₁ , and the second measurement Based on the sound data, the delay characteristic (second delay time TD ₂ ) of the sound processing device 200 is detected. For this reason, in the sound specific measurement of the system to be measured, in addition to the specified time difference TD ₁ , the delay characteristic of the sound processing device 200 is taken into consideration, so that the measurement sound signal X (t) and the recording signal Y (t ) Can be grasped with very high accuracy.

  Further, in this embodiment, the processing control unit 110 performs the sound processing of the sound processing device 200 based on the recording result of the sound collecting result at the predetermined sound collecting position, the specified time difference, and the delay characteristic of the sound processing device 200. Analyze the acoustic characteristics of the system to be measured determined by the combination of the output position and the predetermined sound collection position. For this reason, it can measure simply, ensuring the measurement precision of the acoustic characteristic of a to-be-measured system.

  In this embodiment, the display unit 140 displays the analysis result of the processing control unit 110 of the acoustic characteristic measurement result. For this reason, the measurement result of the acoustic characteristics of the system under measurement can be visualized.

  In the present embodiment, the processing control unit 110 analyzes acoustic characteristics for each of a plurality of measured systems having different sound collection positions. A sound pressure distribution still image, a phase distribution still image, and a wavefront moving video obtained based on the measured acoustic characteristics of each system to be measured are displayed on the display unit 140. For this reason, the characteristics of the sound field can be visualized.

<Modification of Example>
Various modifications can be made to the above embodiment.

  For example, in the above-described example, the same modification as in the above-described embodiment can be performed.

DESCRIPTION OF SYMBOLS 100 ... Acoustic characteristic measuring apparatus 110 ... Processing control unit (a part of sound signal output part, a part of recording part, a specific part,
Calibration section, analysis section)
150 ... Signal output unit (part of sound signal output unit)
160 ... Sound collection unit (part of recording section)
DESCRIPTION OF SYMBOLS 700 ... Acoustic characteristic measuring apparatus 720 ... Sound signal output part 730 ... Recording part 740 ... Specific part 750 ... Calibration part 760 ... Analysis part 770 ... Display part

Claims (10)

A sound signal output unit that outputs a measurement sound signal over a second time in response to an output start command issued after the first time has elapsed since the start of the recording operation;
From the start time of the recording operation to the end time of the output operation of the measurement sound signal, the sound corresponding to the measurement sound signal output by the sound processing device that has received the measurement sound signal is collected at a predetermined sound collection position. A recording unit that records the recorded sound results;
A specifying unit that specifies a time difference between an execution time of the recording operation and a sum of the first time and the second time;
An acoustic characteristic measuring apparatus comprising:   The recording result when the position near the sound output position of the sound processing device is the sound collection position for calibration, the time difference specified by the specifying unit when the position is the sound collection position for calibration, and the measurement sound signal The acoustic characteristic measuring apparatus according to claim 1, further comprising a calibration unit that detects a delay characteristic of the sound processing apparatus based on the sound source data of the sound processing apparatus.   The sound processing device based on a recording result including a sound collection result collected at the predetermined sound pickup position, a time difference specified by the specifying unit when the predetermined sound pickup position is set, and the delay characteristic The acoustic characteristic measuring apparatus according to claim 2, further comprising an analysis unit that analyzes an acoustic characteristic of a system to be measured that is determined by a combination of a sound output position of the sound and a predetermined sound collection position.   The acoustic characteristic measuring apparatus according to claim 3, wherein the acoustic characteristic includes an impulse response characteristic.   The acoustic characteristic measuring apparatus according to claim 4, wherein the acoustic characteristic further includes at least one of a frequency characteristic and a phase characteristic.   The acoustic characteristic measurement apparatus according to claim 3, further comprising a display unit that displays an analysis result by the analysis unit. The acoustic characteristics for each of a plurality of measured systems having different sound collection positions are analyzed by the analysis unit,
The acoustic characteristic measuring apparatus according to claim 6, wherein at least one of a still image of sound pressure distribution, a still image of phase distribution, and a moving image of wavefront movement is displayed on the display unit. An acoustic characteristic measurement method used in an acoustic characteristic measurement device including a sound signal output unit, a recording unit, and a specific unit,
A sound signal output step in which the sound signal output unit outputs a measurement sound signal over a second time in response to an output start command issued after the first time has elapsed since the recording operation was started;
From the start of the recording operation to the end of the output operation of the measurement sound signal, the recording unit outputs a sound corresponding to the measurement sound signal output by the sound processing device that has received the measurement sound signal. A recording process for recording including the sound collection results collected at the sound collection position;
A specifying step in which the specifying unit specifies a time difference between an execution time of the recording operation and a sum of the first time and the second time;
An acoustic characteristic measuring method comprising:   An acoustic characteristic measurement program causing a computer included in the acoustic characteristic measurement device to execute the acoustic characteristic measurement method according to claim 8.   10. A recording medium on which the acoustic characteristic measuring program according to claim 9 is recorded so as to be readable by a computer included in the acoustic characteristic measuring apparatus.

Images