JP2000097759A - Sound field measuring device, its method, and computer readable record medium storing sound field analysis program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive sound field measuring device capable of detecting band energy by a simple process and constitution. SOLUTION: A sound signal collected by a microphone 11 is converted into digital data by an A/D conversion part 12, and is fast Fourier converted by a FFT part 13, and is converted into data in the frequency domain, and is stored in a memory part 14. Based on the conversion data, a spectrum value detection part 16 detects data in response to a center frequency of a 1/6 octave band, and outputs them to a display part 18 as spectrum data of each band. Furthermore, a band value calculation part 17 detects a range of FFT resultant data belonging to the 1/6 octave band, and acquires a total value of the FFT resultant data within the range, and outputs it to the display part 18 as energy data. In the display part 18, the spectrum data and energy data are correspondingly displayed as measuring and analyzing results.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound field measuring apparatus and method capable of easily measuring a desired band energy of an audio signal, and a computer-readable recording medium on which a sound field analyzing program is recorded.

[0002]

2. Description of the Related Art As the fast Fourier transform (FFT) algorithm has begun to be widely used, FFT analyzers for measuring and analyzing sound, vibration, and the like can be constructed at low cost, and have begun to be widely used. On the other hand, in the development of general consumer devices / equipment, there are demands for lowering noise and vibration and higher performance acoustic effects. To meet such demands, sound fields in various environments are required. Measurement
An analysis needs to be performed. As a result, FFT analyzers are widely used for measuring and analyzing such sound fields.
FFT analyzer used for sound field measurement, in other words,
A sound field measuring apparatus having an FFT analyzer generally has a configuration in which an input sound signal is A / D converted, FFT is performed, frequency analysis is performed, and spectrum data is displayed.

[0003]

However, if the sound field is to be measured and analyzed more strictly, the data is insufficient with only the spectrum for each frequency, and data such as energy for each frequency band is required. The case is increasing. For this reason, finely detected spectrum data is processed by thinning or rounding it and displayed.However, even if such processing is performed, it is still spectral data and not energy data. No, it was hard to be new data for sound field analysis. In addition, when such thinning or rounding is performed, even if important data exists, it may not be accurately reflected even if it exists, which has been a problem.

[0004] From such a point, there is a strong demand to obtain energy of each frequency band, that is, data of band energy. On the other hand, a circuit for detecting such band energy requires a large number of analog filters or Since a digital filter is required and the system is completely separate from a circuit for detecting a spectrum, there is a problem that the configuration is complicated, the hardware configuration is increased, and the price of the apparatus is significantly increased.

Accordingly, it is an object of the present invention to provide an inexpensive sound field measuring device capable of detecting band energy with a simple process and configuration. It is another object of the present invention to provide a sound field measuring method capable of detecting band energy with a simple process and configuration. Further, the object of the present invention is
It is an object of the present invention to provide a computer-readable recording medium on which a sound field analysis program is recorded so that band energy can be detected by simple processing using data obtained from a conventional FFT analyzer.

[0006]

In order to solve the above-mentioned problems, a sound field measuring apparatus according to the present invention comprises: an analog-to-digital conversion circuit for sequentially converting an input arbitrary sound signal into a digital audio signal; A conversion means for converting the digital audio signal by a predetermined conversion method for each predetermined number and generating a predetermined number of pieces of conversion data each indicating a predetermined frequency component; and for each predetermined predetermined frequency band. And energy data calculating means for calculating energy data of the frequency band based on the converted data indicating the frequency components included in the frequency band in the generated converted data.

[0007] Preferably, for each predetermined frequency, spectrum data at the frequency is detected based on conversion data indicating a frequency component near the frequency in the generated conversion data. It further has a spectrum data detecting means.

[0008] More specifically, the energy data calculating means is configured to generate, for each predetermined frequency band, conversion data representing a frequency component included in the frequency band in the generated conversion data. The values are summed to obtain energy data of the frequency band. Also, specifically,
The spectrum data detecting means extracts, for each predetermined frequency, conversion data indicating a component of a frequency closest to the frequency in the generated conversion data, and converts the conversion data at the frequency. Let it be spectrum data.

More specifically, the energy data calculating means calculates the energy data for each 1 / n (n is an arbitrary natural number) octave band, and the spectrum data detecting means calculates the 1 / n. The spectrum data is detected for each center frequency of n octave bands. More specifically, the conversion means converts the converted digital audio signal into conversion data indicating the predetermined frequency component by fast Fourier transform.

[0010] Preferably, the apparatus further comprises display means for displaying the detected spectrum data for each predetermined frequency and the calculated energy data for each predetermined frequency band.

In the sound field measuring method of the present invention, an arbitrary input sound signal is sequentially converted into a digital audio signal, and the converted digital audio signals are converted into a predetermined number of digital audio signals by a desired conversion method. Convert, generate a predetermined number of conversion data each indicating a predetermined frequency component, and, for each predetermined predetermined frequency band, indicate a frequency component included in the frequency band in the generated conversion data. The energy data of the frequency band is calculated based on the converted data.

A computer-readable recording medium in which the sound field analysis program of the present invention is recorded is provided by a predetermined number of audio conversion data indicating a predetermined frequency component for each predetermined frequency band. A sound field analysis program having an energy data calculation module for extracting the audio conversion data indicating the frequency components included in the frequency band and calculating energy data of the frequency band based on the extracted audio conversion data. Is recorded. Preferably, for each predetermined frequency, a spectrum data detection module that detects spectrum data at the frequency based on audio conversion data indicating a frequency component near the frequency in the audio conversion data. Is recorded.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described.
This will be described with reference to FIGS. In the present embodiment, a signal of an arbitrary sound (hereinafter, referred to as an audio signal) collected by a microphone is divided into 1 /
A frequency analysis is performed on 60 bands every 6 octave bands, and spectrum data at each band center frequency,
The present invention will be described by exemplifying a sound field measuring device that detects energy data of each band and displays the data in association with each other.

FIG. 1 is a block diagram showing the configuration of the sound field measuring device. The sound field measurement device 10 includes a microphone 11, an analog / digital (A / D) conversion unit 12, a fast Fourier transform (FFT) unit 13, a memory unit 14, a reference table unit 15, a spectrum value detection unit 16, a band value calculation unit. 17 and a display unit 18.

First, the configuration of each part of the sound field measuring device 10 will be described. The microphone 11 is a means for inputting an audio signal, and the input analog audio signal is output to the A / D converter 12.

The A / D converter 12 includes a microphone 11
The analog audio signal collected and input in is sampled at a predetermined sampling frequency, quantized at a predetermined quantization level, converted into a digital signal, and
Output to FT section 13. A / D converter 1 of the present embodiment
At 2, sampling was performed at 44.1 kHz, and 16
Quantize to bits.

The FFT unit 13 performs a fast Fourier transform on the digital audio data input from the A / D converter 12 for each predetermined number, and converts the digital audio data into frequency domain data.
The obtained data is stored in the memory unit 14. The FFT unit 13 according to the present embodiment performs fast Fourier transform (FFT) on the data for every 8192 samples, and generates data of the FFT result of 8192 points. In the following processing, among the data n1 to n8192 of 8192 points obtained by the FFT, valid data n1 to n3715 up to 20 kHz are used.

FIG. 2 shows a specific example of the data of the generated FFT result. FIG. 2 is a diagram showing half data n1 to n4096 on the low frequency side among the data n1 to n8192 of 8192 points obtained by the FFT. In addition,
In FIG. 2, the data n1 side is a low frequency component, and the data n4096 side is a high frequency component. As shown in FIG. 2, the result of the FFT can be represented as a spectrum at each frequency value at equal frequency intervals every 5.38 Hz.

The memory unit 14 is a memory for storing FFT result data obtained by the FFT unit 13,
It is composed of a general-purpose memory such as M or SRAM. The data of the FFT result stored in the memory unit 14 is appropriately referred to by the spectrum value detection unit 16 and the band value calculation unit 17.

The reference table section 15 stores a table in which correspondence of data is recorded for generating data of a result of 1/6 octave band analysis from FFT result data in which frequency components are indicated at equal frequency intervals. This is a recorded memory, which is referred to by the spectrum value detector 16 and the band value calculator 17. FIG. 3 shows a specific example of the reference table recorded in the reference table unit 15. As shown in FIG. 3, the reference table corresponds to 60 1/6 octave bands output as the measurement and analysis results by the sound field measurement device 10, and data N for specifying the 1/6 octave band.
o. The center frequency of the 1/6 octave, the number of the FFT result data corresponding to the 1/6 octave spectrum data, and the range of the FFT result data corresponding to the 1/6 octave band are recorded.

The spectrum value detection section 16 detects data corresponding to the center frequency of the 1/6 octave band from the FFT result data n1 to n3715, and outputs the data to the display section 18 as spectrum data. Spectrum value detector 1
6 indicates a frequency closest to the center frequency of each of the 60 1/6 octave bands.
The T result data is sequentially detected by referring to the reference table recorded in the reference table unit 15, and the FFT result data is read from the memory unit 14 and output to the display unit 18 as it is. For example, FIG.
For example, with respect to the FFT result data as shown in the above, each FFT result data as shown by ● is extracted as spectrum data corresponding to a 1/6 octave band.

The band value calculation section 17 detects energy data of each band of 1/6 octave band from the FFT result data n1 to n3715, and outputs it to the display section 18. The band value calculation unit 17 detects FFT result data corresponding to the frequency components included in each of the 60 1/6 octave bands, calculates the sum of the values, and calculates the energy of the band. The data is output to the display unit 18 as indicated data. The detection of the FFT result data corresponding to the frequency components included in each band is performed by referring to the reference table recorded in the reference table unit 15 in the band value calculation unit 17 of the present embodiment. Also, this sum is 1 /
It indicates the area of a 6-octave band, and can be regarded as an effective value of octave energy.

More specifically, for example, 1000
When obtaining energy data of a 1/6 octave band having a center frequency of 1 Hz, first, referring to the reference table shown in FIG.
It is detected that it is sufficient to add the T result data n176 to the 195th FFT result data n195. Next, these data n176 to n195 are stored in the memory unit 14
And sequentially add them. The sum thus obtained is output to the display unit 18 as energy data of the 1/6 octave band. as a result,
For example, for the FFT result data as shown in FIG. 2, for the center spectrum corresponding to 1000 Hz,
Addition of the FFT result data in the range B is obtained, and the energy data of 1/6 octave is set in this range as a band.

The display section 18 associates the spectrum data input from the spectrum value detection section 16 with the energy data input from the band value calculation section 17 for each of the 60 1/6 octave bands. It is displayed on a display screen (not shown). Sound field measuring device 10 of the present embodiment
In FIG. 4, for example, as shown in FIG. 4, the spectrum data and the energy data are arranged vertically so that the corresponding bands are arranged at the same position in the horizontal direction, the spectrum data is a thin line, and the energy data is a predetermined width. Is displayed using a bar-shaped line having

Next, the sound field measuring apparatus 10 having such a configuration will be described.
Will be described. First, the analog audio signal to be measured collected by the microphone 11 is A /
The data is input to the D conversion unit 12, sampled and quantized at 44.1 kHz, 16 bits, and converted into digital data. Fast Fourier transform is performed by the FFT unit 13 for each of the 8192 points of the digital data, and frequency domain data n1 to n81 each showing a predetermined frequency component.
92 is generated and recorded in the memory unit 14.

The data n1 recorded in the memory unit 14
Effective data n1 to 20kHz in
Based on n3715, the center frequency spectrum data is detected by the spectrum value detecting section 16 and the band energy data is detected by the band value calculating section 17 for every 60 1/6 octave bands. That is, the spectrum value detection unit 16 refers to the reference table stored in the reference table unit 15 and
Data corresponding to the center frequency of the / 6 octave band is detected, and the data is sequentially read from the memory unit 14 and output to the display unit 18 as spectrum data of each band.

The band value calculating section 17 refers to the reference table stored in the reference table to detect the range of the FFT result data belonging to each 1/6 octave band, Then, the FFT result data in that range is read from the memory unit 14, the sum of the values is obtained, and output to the display unit 18 as energy data. As a result, in the display unit 18,
For example, as shown in FIG. 4, spectrum data and energy data, which are measurement / analysis results, are displayed in association with each other.

As described above, in the sound field measuring apparatus 10 of the present embodiment, the spectrum data in the 1/6 octave band, that is, the FFT result data are summed up, and the area in the band is calculated in a pseudo manner. Data corresponding to the octave energy effective value is detected. Therefore, 1
The energy value for each / 6 octave band can be easily detected, and the energy analysis of the audio signal can be easily performed. In addition, the energy data detection process only needs to add a little addition process to the FFT measurement program, so that the program size hardly changes.

Further, spectrum data of a frequency for each 1/6 octave band is detected by selecting data of a frequency that is closer to the FFT result data.
Therefore, the spectrum data and the energy data for each 1/6 octave band are detected by the same processing by the substantially same processing system, and the hardware configuration and the processing contents can be simplified. . Further, since the two data can be detected simultaneously and displayed in association with each other, the analysis of the audio signal can be performed more efficiently. In the log scale of 1/6 octave, both the spectrum value and the octave band energy value have similar values at low frequencies. However, as the frequency increases, the difference increases, and the accuracy as an energy value improves.

For example, as compared with a case where a sound field measuring device having an equivalent function is configured by using an analog filter, measurement and analysis can be performed with higher resolution and the configuration can be made at a low cost. In addition, when compared to a case where a sound field measurement device having the same function is configured using a digital filter, for example, the FFT operation is fundamental, so that the frequency and level of the peak spectrum in the band can be measured in real time. There is an advantage that you can.

It should be noted that the present invention is not limited to the present embodiment, and various suitable modifications are possible.
For example, in the present embodiment, the sound field measuring device 10
Has been described as a single device including the display unit 18, but the actual device configuration is not limited to such a case. For example, as shown in FIG. 5, a configuration in which a microphone 21, a general-purpose FFT analyzer 22, and a personal computer 23 are connected as illustrated may be used. The FFT analyzer 22 normally has the functions of the A / D conversion unit 12, the FFT unit 13, and the memory unit 14 in the sound field measurement device 10. Therefore, if the functions of the reference table section 15, the spectrum value detection section 16, the band value calculation section 17, and the display section 18 are provided in the personal computer 23, the configuration shown in FIG. The configuration is exactly the same as the configuration of the sound field measurement device 10 shown.

If the FFT analyzer 22 has a function as an octave analyzer and further has a function of the spectrum value detecting section 16, the personal computer 23 has the reference table section 15, the band value It is only necessary to have the functions of the calculation unit 17 and the display unit 18. In any case, the functions of the reference table section 15, the spectrum value detection section 16 and the band value calculation section 17 are the same as those of the personal computer 2
It is preferable that the software is configured on software 3. The present invention may be implemented in, for example, such various forms.

Further, in the sound field measuring apparatus 10 of the present embodiment, the frequency components are indicated at equal frequency intervals.
When generating data of the result of the 1/6 octave band analysis from the FT result data, the reference table is referred to. However, since this correspondence is uniquely obtained by the calculation, the calculation is performed without using the reference table. And the corresponding data may be detected. In the sound field measuring device 10, the result of the 1/6 octave band analysis is generated from the FFT result data.
/ 3 octave analysis may be used.

In addition, the detailed configuration of each part of the sound field measuring device 10 may be arbitrarily determined. For example, FFT unit 1
As the FFT algorithm in No. 3, any one of various widely proposed algorithms may be selected and used. Further, in the sound field measuring device 10, the memory unit 14 and the reference table unit 15 have different configurations, but may be configured on substantially the same memory. The data detected and calculated by the spectrum value detection unit 16 and the band value calculation unit 17 are only displayed on the display unit 18, but may be recorded in the memory unit 14. This is preferable because the data recorded in the memory unit 14 can be displayed as it is when redisplaying the analysis result. Further, the method of displaying data on the display unit 18 is not limited to the example shown in FIG. 4 and may be displayed in any form.

The use of the sound field measuring device 10 is not limited at all. For example, analysis of noise of vehicles, aircraft, etc., analysis of noise in any place including inside a vehicle, in an aircraft, etc., analysis of telephone sound quality and various alarm sounds, etc., determination of equalizer characteristics It may be used for any purpose such as analysis of audio data.

[0036]

As described above, according to the present invention,
An inexpensive sound field measuring device capable of detecting band energy with a simple process and configuration can be provided. In addition, it is possible to provide a sound field measurement method capable of detecting band energy with a simple process and configuration. Further, it is possible to provide a computer-readable recording medium on which a sound field analysis program is recorded, such that band energy can be detected by simple processing using data obtained from a conventional FFT analyzer. .

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a sound field measuring device according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining a process in each unit of the sound field measurement device shown in FIG. 1;

FIG. 3 is a diagram showing a reference table recorded in a reference table section of the sound field measuring device shown in FIG. 1;

FIG. 4 is a diagram illustrating a sound field analysis result displayed on a display unit of the sound field measurement device illustrated in FIG. 1;

FIG. 5 is a diagram showing another configuration example of the sound field measuring device of the present invention.

[Explanation of symbols]

10: sound field measuring device, 11: microphone, 12: A
/ D converter, 13 ... FFT unit, 14 ... memory unit, 15 ...
Reference table part, 16 ... Spectral value detection part,
17: Band value calculation unit, 18: Display unit, 21: Microphone, 22: FFT analyzer, 23: Personal computer

Claims (17)

[Claims] An analog-to-digital conversion circuit for sequentially converting an arbitrary input audio signal into a digital audio signal; and converting the converted digital audio signals into a predetermined number by a desired conversion method. A conversion unit for generating a predetermined number of conversion data each indicating a predetermined frequency component; and for each predetermined predetermined frequency band, a frequency component included in the frequency band in the generated conversion data. A sound field measuring device having energy data calculating means for calculating energy data of the frequency band based on the converted data. 2. Spectral data for detecting spectrum data at a predetermined frequency based on conversion data indicating a frequency component near the frequency in the generated conversion data for each predetermined frequency. The sound field measurement device according to claim 1, further comprising a detection unit. 3. The method according to claim 2, wherein said energy data calculating means sums, for each predetermined frequency band, a value of the conversion data indicating a frequency component included in the frequency band in the generated conversion data. The sound field measurement device according to claim 2, wherein the data is energy data of the frequency band. 4. The spectrum data detecting means extracts, for each predetermined frequency, conversion data indicating a component of a frequency closest to the frequency in the generated conversion data, and The sound field measurement device according to claim 2, wherein the data is spectrum data at the frequency. 5. The method according to claim 1, wherein said energy data calculating means comprises: for each 1 / n (n is an arbitrary natural number) octave band,
The sound field measurement device according to claim 2, wherein the energy data is calculated, and the spectrum data detection unit detects the spectrum data for each center frequency of the 1 / n octave band. 6. The sound field measuring apparatus according to claim 2, wherein said conversion means converts the converted digital audio signal into conversion data indicating the predetermined frequency component by fast Fourier transform. 7. The sound field measuring apparatus according to claim 2, further comprising display means for displaying the detected spectrum data for each predetermined frequency and the calculated energy data for each predetermined frequency band. 8. An input arbitrary sound signal is sequentially converted into a digital audio signal, and the converted digital audio signals are converted by a predetermined conversion method for each predetermined number, and each predetermined frequency component is converted. Generate a predetermined number of conversion data shown, for each predetermined predetermined frequency band, based on the conversion data indicating the frequency components included in the frequency band in the generated conversion data, A sound field measurement method that calculates energy data in the frequency band. 9. Further, for each predetermined frequency,
The sound field measurement method according to claim 8, wherein spectrum data at the frequency is detected based on conversion data indicating a component of a frequency near the frequency in the generated conversion data. 10. The method according to claim 1, wherein calculating the energy data includes, for each predetermined frequency band, summing up the values of the conversion data indicating the frequency components included in the frequency band in the generated conversion data. The sound field measuring method according to claim 9, wherein the sound field measuring method is performed by using energy data of the frequency band. 11. The method according to claim 1, wherein the detecting of the spectrum data includes extracting, for each predetermined frequency, conversion data indicating a component of a frequency closest to the frequency in the generated conversion data, The sound field measurement method according to claim 9, wherein the method is performed by converting data into spectrum data at the frequency. 12. In the calculation of the energy data, the energy data is calculated for every 1 / n (n is an arbitrary natural number) octave band, and in the detection of the spectrum data, the 1 / n octave is used. The sound field measuring method according to claim 9, wherein the spectrum data is detected for each center frequency of the band. 13. The conversion of the converted digital audio signal into conversion data indicating the predetermined frequency component,
The sound field measurement method according to claim 9, wherein the sound field measurement is performed by fast Fourier transform. 14. Extracting, from a predetermined number of pieces of audio conversion data each indicating a predetermined frequency component, the audio conversion data indicating a frequency component included in the predetermined frequency band for each predetermined frequency band. A computer-readable recording medium in which a sound field analysis program having an energy data calculation module for calculating energy data of the frequency band based on the extracted audio conversion data is recorded. 15. Spectral data detection for detecting spectrum data at a frequency based on audio conversion data indicating a frequency component near the frequency in the audio conversion data for each predetermined frequency. A computer-readable recording medium on which the sound field analysis program according to claim 14 further has a module. 16. A display module for displaying the detected spectrum data for each predetermined frequency and the calculated energy data for each predetermined frequency band in a desired display form on a desired display screen. A computer-readable recording medium on which the sound field analysis program according to claim 15 is recorded. 17. A digital audio signal sequentially input is converted by a predetermined conversion method for each predetermined number,
The sound field analysis according to claim 14, further comprising a conversion processing module configured to generate a predetermined number of conversion data each indicating a predetermined frequency component, wherein the calculation of the energy data is performed using the generated conversion data. A computer-readable recording medium on which a program is recorded.