JP2020041978A - Measuring device, measurement method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a distance measuring device capable of measuring a distance using a sound wave in a frequency band in an audible region in a noisy environment. SOLUTION: A representative value calculated by calculating a representative value of a sound pressure level of each frequency by using an analysis unit 13 that analyzes a sound wave in an audible frequency band sampled for a certain period of time by a high-speed Fourier conversion process and an analysis result by the analysis unit. The frequency extraction unit 14 that extracts the measurement frequency based on the value of the value and the sound wave information of the sound wave of the measurement frequency extracted by the frequency extraction unit are generated, and the sound wave information of the generated measurement frequency sound wave is output to the speaker 17. The sound wave information of the waveform generation unit 15 and the sound wave of the measurement frequency generated by the waveform generation unit is acquired, and the sound wave information of the reflected wave of the sound wave of the measurement frequency output from the speaker is acquired, and the sound wave of the acquired measurement frequency. The distance calculation unit 16 for calculating the distance to the object to be measured by using the sound wave information of the reflected wave and the sound wave information of the sound wave of the measurement frequency is provided. [Selection diagram] Fig. 1

Description

  The present invention relates to a measuring device, a measuring method, and a program for measuring a distance from a measurement target.

  In the inspection of facility equipment such as a water pump and an exhaust fan, an inspector patrols the installation location, distinguishes operating noise by hearing, detects the presence or absence of abnormal noise, and determines whether or not the equipment has deteriorated. However, the inspection work depending on the hearing of the inspector may have different judgment results depending on the skill and physical condition of the inspector.

  As a method of quantitatively capturing the operating sound of the equipment, there is a method of measuring the sound pressure level of a sound emitted from a sound source and digitizing the measured sound pressure level.

  Patent Literature 1 discloses a technique for measuring the sound pressure level of noise caused by a noise source while eliminating the influence of background noise. In the method of Patent Document 1, a frequency component of a low sound pressure level of a background noise is detected from each frequency component of a frequency spectrum of the noise, and a component of the detected frequency is measured among noises from a noise source to be measured.

  When measuring noise, if the distance between the noise source and the sound level meter changes, the measured noise value is affected. Therefore, it is required to measure the sound pressure level while keeping the distance between the noise source and the sound level meter constant, or to measure the sound pressure level while measuring the distance between the noise source and the sound level meter. In a general distance measuring method, an electromagnetic wave such as a microwave or a millimeter wave or an ultrasonic wave is output toward an object, and a distance is calculated from an attenuation degree and a delay time of the returned sound wave. Since such a distance measuring method requires a source of electromagnetic waves or ultrasonic waves, there are problems such as reduced convenience in carrying the device and increased cost.

  Patent Document 2 discloses a distance that measures a distance between a speaker and a microphone by using a speaker that can output audible sound and ultrasonic wave and a microphone that can collect audible sound and ultrasonic wave. A measurement device is disclosed.

  Patent Document 3 discloses a noise / distance measuring device including a sensor unit that captures an object to be measured as an image, optically measures a distance to the object to be measured, and collects nearby sounds. ing. The device of Patent Literature 3 controls the attitude of the sensor unit in accordance with an operation from the outside, and adjusts the attitude of the sensor unit to a position where an object to be measured can be captured as an image.

JP 2001-159559 A Japanese Patent No. 4,960,838 JP 07-190848 A

  According to the technique of Patent Literature 1, it is possible to measure the sound pressure level of noise from a noise source to be measured without being affected by background noise. However, the technique of Patent Literature 1 has a problem that a sound wave having a frequency in an audible region interferes with environmental noise and makes it difficult to detect a change in the sound wave.

  According to the device of Patent Document 2, an impulse response is obtained from a transmission signal and a reception signal, and the distance between the speaker and the microphone is obtained from the result. Therefore, the distance can be measured with high accuracy even with a general speaker and a microphone. However, the method of Patent Document 2 has a problem that a special mechanism for handling ultrasonic waves needs to be added because ultrasonic waves in a frequency region higher than the frequency of environmental noise are used.

  According to the device of Patent Literature 3, the distance to the object to be measured can be measured in a non-contact manner, and the noise level in the vicinity of the measuring point at the measured distance can be measured. However, the method of Patent Document 3 requires imaging means, and thus has problems such as reduced convenience in carrying the device and increased cost.

  An object of the present invention is to solve the above-described problem and to provide a distance measuring device that enables distance measurement using sound waves in a frequency band in an audible region in a noise environment.

  A measuring device of one embodiment of the present invention is a distance measuring device that measures a distance to a measurement target by collecting a reflected wave of a sound wave output from a speaker toward the measurement target with a microphone. An analyzer that samples sound waves in an audible frequency band to be collected for a certain period of time, and analyzes the sampled sound waves using a fast Fourier transform process to generate time-series data of a frequency spectrum; and a frequency generated by the analyzer. A frequency extraction unit that calculates a representative value of the sound pressure level of each frequency using the time series data of the spectrum and extracts a measurement frequency based on the calculated value of the representative value, and a measurement frequency that is extracted by the frequency extraction unit. A waveform generator that generates sound wave information of the sound wave, and outputs the sound wave information of the sound wave of the generated measurement frequency to the speaker; Acquisition of the sound wave information of the sound wave of the measurement frequency generated from the speaker, acquisition of the sound wave information of the reflection wave of the sound wave of the measurement frequency output from the speaker, A distance calculation unit that calculates a distance from the measurement target object using the sound wave information of the sound wave.

  A measurement method according to one embodiment of the present invention is a measurement method for collecting a reflected wave of a sound wave output from a speaker toward a measurement target with a microphone to measure a distance from the measurement target, and includes an information processing apparatus. However, a sound wave in an audible frequency band collected by a microphone is sampled for a certain period of time, and the sampled sound wave is analyzed using a fast Fourier transform process to generate time-series data of a frequency spectrum. Calculate the representative value of the sound pressure level of each frequency using the series data, extract the measurement frequency based on the value of the calculated representative value, generate the sound wave information of the sound wave of the extracted measurement frequency, and generate the generated measurement frequency. The sound wave information of the sound wave of the sound wave is output to the speaker, the sound wave information of the reflected wave of the sound wave of the measurement frequency output from the speaker is obtained, and the obtained measurement frequency And calculates the distance to the measurement object using the acoustic information of sound waves information and the measurement frequency of the reflected wave of the sound wave.

  A program according to one embodiment of the present invention is a program for collecting a reflected wave of a sound wave output from a speaker toward a measurement target with a microphone to measure a distance to the measurement target, and the sound is collected by the microphone. A process of sampling a sound wave in an audible frequency band for a certain period of time, a process of generating time-series data of a frequency spectrum by analyzing the sampled sound wave using a fast Fourier transform process, and a process of generating the time-series data of the generated frequency spectrum. A process of calculating a representative value of the sound pressure level of each frequency using the process, a process of extracting a measurement frequency based on the calculated value of the representative value, a process of generating sound wave information of a sound wave of the extracted measurement frequency, and generating Processing of outputting the sound wave information of the sound wave of the measured frequency to the speaker, and processing of the reflected wave of the sound wave of the measurement frequency output from the speaker. A process for acquiring a wave information, to execute a process of calculating the distance to the measurement object using ultrasound information of the reflected wave and the acoustic information of the sound wave of the measurement frequency of the acoustic wave of the obtained measured frequency to the computer.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the distance measuring device which can perform distance measurement using the sound wave of the frequency band of an audible area under a noise environment.

It is a block diagram showing an example of composition of a measuring device concerning a 1st embodiment of the present invention. FIG. 3 is a conceptual diagram illustrating an example of sampling data collected by the measurement device according to the first embodiment of the present invention. For the first frequency f ₁ of the measuring device is extracted according to a first embodiment of the present invention is a conceptual diagram for explaining. 4 is an example of a correlation table used for distance measurement by the measurement device according to the first embodiment of the present invention. FIG. 4 is a conceptual diagram illustrating an example of display information displayed by the measuring device according to the first embodiment of the present invention. 5 is a flowchart for describing an outline of an operation of the measuring device according to the first embodiment of the present invention. 5 is a flowchart for describing a waveform generation process of the measurement device according to the first embodiment of the present invention. 5 is a flowchart for explaining a distance measurement process of the measurement device according to the first embodiment of the present invention. 5 is a flowchart for describing a noise value measurement process of the measurement device according to the first embodiment of the present invention. It is a block diagram showing an example of composition of a measuring device concerning a 2nd embodiment of the present invention. It is a flow chart for explaining waveform generation processing of a measuring device concerning a 2nd embodiment of the present invention. It is a flow chart for explaining distance measurement processing of a measuring device concerning a 2nd embodiment of the present invention. It is a block diagram showing an example of composition of a distance measuring device concerning a 3rd embodiment of the present invention. FIG. 2 is a block diagram illustrating an example of a hardware configuration that implements a distance measuring device of the measuring device according to each embodiment of the present invention.

  An embodiment for carrying out the present invention will be described below with reference to the drawings. However, the embodiments described below have technically preferable limitations for carrying out the present invention, but do not limit the scope of the invention. In all the drawings used in the description of the following embodiments, the same parts are denoted by the same reference numerals unless otherwise specified. In the following embodiments, repetitive description of similar configurations and operations may be omitted.

(First embodiment)
First, a measuring device according to a first embodiment of the present invention will be described with reference to the drawings. The measurement device of the present embodiment samples sound waves collected from a direction of a noise measurement target (also referred to as a measurement target), and generates a sound wave of a specific frequency based on an analysis result of the sampled data (waveform generation). Stage). The measuring device of the present embodiment outputs the generated sound wave of the specific frequency toward the measurement object, collects the sound wave of the specific frequency collected from the direction of the measurement object, and attenuates the sound wave of the specific frequency. Is used to measure the distance to the object to be measured (also referred to as a distance calculation step).

(Constitution)
FIG. 1 is a block diagram illustrating an example of a configuration of the measuring device 1 according to the present embodiment. As shown in FIG. 1, the measuring device 1 includes a microphone 11, a volume measuring unit 12, an FFT analyzing unit 13, a first frequency extracting unit 14, a waveform generating unit 15, a distance calculating unit 16, a speaker 17, and a display unit 18. . The FFT analysis unit 13, the first frequency extraction unit 14, the waveform generation unit 15, and the distance calculation unit 16 constitute a distance measurement device 10 (also referred to as a measurement device). The distance measurement device 10 may have a configuration independent of those components as long as the distance measurement device 10 is connected to the microphone 11, the volume measurement unit 12, the speaker 17, and the display unit 18.

  The microphone 11 collects sound waves in an audible frequency band. The microphone 11 preferably has directivity. The microphone 11 outputs the collected sound waves in the audible frequency band to the sound volume measurement unit 12 and the FFT analysis unit 13.

  The sound volume measurement unit 12 acquires sound waves in the audible frequency band from the microphone 11. The sound volume measuring unit 12 calculates the sound volume of the sound wave acquired from the microphone 11. For example, the volume measuring unit 12 calculates the sound pressure level of the collected sound wave. The volume measurement unit 12 outputs the calculated volume to the display unit 18.

Specifically, the volume measuring unit 12 calculates the sound pressure level L _p of sound waves by the microphone 11 is collected as a volume. The sound pressure level _Lp is defined by the following expression 1 using the sound pressure p. However, in Equation 1, the reference value p ₀ (= 20 micropascal) is the minimum audible sound pressure of a healthy human.
L _p = 10 × log ₁₀ (p ² / p ₀ ² ) = 20 × log ₁₀ (p / p ₀ ) (1)
The FFT analysis unit 13 samples sound waves in the audible frequency band from the microphone 11 for a certain period of time. The FFT analysis unit 13 performs a fast Fourier transform (FFT) analysis on the sampled sound waves. The FFT analysis unit 13 generates time-series data of a frequency spectrum by performing FFT analysis on the sampled sound waves. The FFT analysis unit 13 outputs the generated time-series data of the frequency spectrum to the first frequency extraction unit 14 as an FFT analysis result.

FIG. 2 is a diagram illustrating an example of a time-series spectrum generated by the FFT analysis unit 13 by the FFT analysis. Time series spectrum of Figure 2 is obtained by three-dimensionally express the relationship between the time t and frequency f and the sound pressure level L _p. For example, the FFT analysis unit 13 samples a sound wave from the microphone 11 for a certain period of time, divides the sampled data at equal intervals, performs FFT processing on each of the divided data, and converts time-series data of a frequency spectrum as shown in FIG. Generate.

The first frequency extracting unit 14 acquires an FFT analysis result from the FFT analyzing unit 13. The first frequency extraction unit 14 calculates the variance of the sound pressure level of each frequency based on the FFT analysis result obtained from the FFT analysis unit 13. The first frequency extracting unit 14 extracts a frequency at which the variance of the sound pressure level of each frequency is smaller than a predetermined value (hereinafter, a first frequency f ₁ ). When obtaining the distance from the attenuation rate of the sound wave, the smaller the variance, the higher the accuracy. Therefore, in the present embodiment, the first frequency extracting unit 14 extracts the frequency with the smallest variance.

The predetermined value for the variance is determined by the measurement accuracy of the distance to be obtained and the output value of the speaker. For example, to obtain a measurement accuracy of 10%, the value obtained by dividing the variance by the output value of the speaker may be equal to or less than the measurement accuracy. Therefore, the predetermined value can be calculated by the following equation (2).
(Predetermined value) = 0.10 × (output value) (2)
Figure 3 is a conceptual diagram for explaining a first frequency f ₁ of the first frequency extraction unit 14 extracts. In the example of FIG. 3, the first frequency extracting unit 14 extracts the first frequency f ₁ at which the variance _VL is minimum, using the correlation between the frequency f and the variance _VL .

The first frequency extracting unit 14 outputs the extracted first frequency f ₁ to the waveform generating unit 15 at least in a waveform generating stage. Note that the first frequency extracting unit 14 may output the first frequency f ₁ to the waveform generating unit 15 in the distance calculation stage, if necessary.

Further, the first frequency extracting unit 14 outputs the sound pressure level of the sound wave of the first frequency f ₁ to the distance calculating unit 16 at least in a distance calculating stage.

Waveform generating unit 15 acquires the first frequency f ₁ from the first frequency extraction section 14. The waveform generation unit 15 generates the sound wave information of the first frequency f ₁ acquired from the first frequency extraction unit 14. The sound wave information of the first frequency f ₁ generated by the waveform generator 15 includes the sound pressure level of the sound wave output from the speaker 17. The waveform generator 15 outputs the generated sound wave information of the first frequency f ₁ to the speaker 17 and the distance calculator 16.

The distance calculation unit 16 acquires the sound wave information of the first frequency f ₁ from the waveform generation unit 15 in the waveform calculation stage. Further, the distance calculation unit 16 acquires the sound wave information of the sound wave of the first frequency f ₁ from the first frequency extraction unit 14 in the distance calculation stage. The distance calculator 16 includes the sound pressure level included in the sound wave information of the sound wave of the first frequency f ₁ acquired from the first frequency extractor 14 in the sound wave information of the first frequency f ₁ acquired from the waveform generator 15. by dividing the sound pressure level, to calculate the attenuation rate of sound waves of the first frequency f _1. Distance calculating section 16, based on the acoustic attenuation factor of the first frequency f _1, and calculates the distance to the measurement object and the measuring apparatus 1. The distance calculation unit 16 outputs the calculated distance between the measurement object and the measurement device 1 to the display unit 18.

  FIG. 4 is an example of a correlation table 160 that summarizes the correlation between the attenuation rate of sound waves and the distance. The distance calculation unit 16 calculates the distance by applying the calculated attenuation rate of the sound wave to the correlation table 160. Note that the correlation between the attenuation rate of the sound wave and the distance is obtained in advance. Further, the distance may be calculated using a function indicating the correlation between the attenuation rate of the sound wave and the distance.

The speaker 17 acquires the sound wave information of the first frequency f ₁ from the waveform generator 15. The speaker 17 outputs a sound wave in an audible frequency band including a sound wave of the first frequency f ₁ based on the sound wave information acquired from the waveform generation unit 15. The speaker 17 preferably has directivity. The microphone 11 and the speaker 17 are installed so that the directivity directions are parallel. For example, the microphone 11 and the speaker 17 are installed on the same surface of the housing of the measuring device 1.

  The display unit 18 acquires the measurement result of the volume measured by the volume measurement unit 12. Further, the display unit 18 acquires the distance to the measurement target calculated by the distance calculation unit 16. The display unit 18 displays the acquired sound volume measurement result and the distance to the measurement target. The display unit 18 is realized by a general monitor.

  FIG. 5 is a conceptual diagram illustrating an example of display information to be displayed on the display unit 18. In the example of FIG. 5, the reference measurement distance display section 181 displays a reference measurement distance that is a reference for measuring the noise value. The measured distance display unit 182 displays the measured distance calculated by the distance calculation unit 16. The noise value display unit 183 displays the sound pressure level measured by the sound volume measurement unit 12 as a noise value (dB: decibel).

  The user of the measuring device 1 recognizes the distance between the measuring object and the measuring device 1 by looking at the display unit 18 and can set the position of the measuring device 1 in accordance with the reference measurement distance. In addition, the user of the measurement device 1 can recognize the noise value measured at the reference measurement distance by looking at the display unit 18.

  The above is the description of the configuration of the measuring device 1 of the present embodiment. The measuring device 1 illustrated in FIG. 1 is an example, and does not limit the configuration of the measuring device 1 according to the present embodiment.

(motion)
Next, the operation of the measuring device 1 will be described with reference to the drawings. In the following, the outline of the operation of the measuring device 1 will be described, and then the details of some operations will be described.

  FIG. 6 is a flowchart for explaining an outline of the operation of the measuring device 1.

  In FIG. 6, first, the measuring device 1 displays a reference measurement distance with the measurement target on the display unit 18 (step S11). Here, the user arranges the measuring device 1 so that the microphone 11 and the speaker 17 face the measurement target according to the reference measurement distance displayed on the display unit 18.

  Next, the measuring device 1 collects sampling data for measuring the distance to the measurement target (Step S12).

  Next, the measuring device 1 measures the distance between the measurement object and the own device using the collected sampling data (step S13).

  Here, the measuring device 1 determines whether or not the distance adjustment is completed based on the measured distance and the reference measurement distance (Step S14).

  If the distance adjustment has not been completed (No in step S14), the measuring device 1 displays the measured distance on the display unit 18 (step S15). Here, the user adjusts the position of the measurement device 1 so that the measurement distance displayed on the display unit 18 matches the reference measurement distance.

  On the other hand, when the distance adjustment is completed (Yes in Step S14), the measuring device 1 performs the noise value measurement (Step S16). For example, when the measurement distance is within 10% of the measurement reference distance, the measurement device 1 displays that the distance adjustment is completed on the display unit 18 and measures the noise value.

  The above is the description of the outline of the operation of the measuring device 1 of the present embodiment. Note that the processing along the flowchart in FIG. 6 is an example, and does not limit the operation of the measuring device 1 of the present embodiment.

  Next, details of the operation of the measuring device 1 will be described with reference to the drawings. In the following, a process of collecting sampling data (step S12 in FIG. 6), a process of measuring a distance to a measurement target (step S13 of FIG. 6), and a process of measuring a noise value (step S16 of FIG. 6) Will be described in order.

[Waveform generation processing]
FIG. 7 is a flowchart for describing the waveform generation processing (step S12 in FIG. 6) for generating a sound wave used for distance measurement.

  In FIG. 7, first, the measuring device 1 collects a sound wave with the microphone 11 (step S121).

  Next, the measuring device 1 performs an FFT analysis on the collected sound waves to obtain a sound pressure level for each frequency (step S122).

  Here, if the sampling data of all frequency bands is not available (No in step S123), the process returns to step S121. The measuring apparatus 1 repeats the processing of steps S121 to S123 until the sampling data of each frequency band is completed.

On the other hand, if the sampling data of all the frequency bands aligned (Yes in step S123), the measuring apparatus 1 analyzes the sampled data for each frequency band, dispersion minimum frequency (hereinafter, referred to as a first frequency f ₁ ) Is extracted (step S124).

Next, the measuring device 1 generates a first frequency f ₁ of the sound wave of the waveform (step S125). Thus, the processing according to the flowchart of FIG. 7 is completed.

  The above is the description of the waveform generation processing of the measuring device 1. Note that the processing in FIG. 7 is an example, and does not limit the waveform generation processing by the measuring device 1.

[Distance measurement processing]
FIG. 8 is a flowchart for explaining the distance measurement processing (step S13 in FIG. 6) for measuring the distance to the measurement target.

8, first, the measurement apparatus 1 outputs the first sound wave frequency f ₁ toward the measuring object (step S131).

Next, the measuring device 1 collects the first wave having a predetermined frequency f ₁ returning from the direction of the measuring object (step S132).

Next, the measuring apparatus 1 calculates the attenuation factor of the sound pressure level of the first frequency f ₁ of the acoustic wave (step S133).

  Next, the measuring device 1 calculates the distance between the measurement object and the own device based on the correlation between the attenuation rate and the distance that is obtained in advance (Step S134). For example, the measuring device 1 acquires a correlation between the attenuation rate and the distance that is obtained in advance as a correlation table.

  Then, the measuring device 1 displays the calculated distance (Step S135).

  The above is the description of the distance measurement processing by the measurement device 1 of the present embodiment. Note that the processing in FIG. 8 is an example, and does not limit the distance measurement processing by the measuring device 1 of the present embodiment.

[Noise value measurement processing]
FIG. 9 is a flowchart for describing the noise value measurement processing (step S16 in FIG. 6) for measuring the noise value.

  In FIG. 9, first, the measuring device 1 collects noise with the microphone 11 (step S161).

  Next, the measuring device 1 calculates a noise value of the collected noise (step S162).

  Then, the measuring device 1 displays the calculated noise value on the display unit 18 (Step S163).

  The above is the description of the noise value measurement processing of the measurement device 1. Note that the processing in FIG. 8 is an example, and does not limit the noise value measurement processing by the measurement device 1.

As described above, the measurement device according to the present embodiment includes the microphone, the volume measurement unit, the FFT analysis unit, the first frequency extraction unit, the waveform generation unit, the speaker, and the display unit. The microphone collects sound waves in at least the audible frequency band. The FFT analysis unit performs FFT analysis on sound waves collected by the microphone. The first frequency extraction unit calculates the variance of the sound pressure level of each frequency using the result of the FFT analysis performed by the FFT analysis unit, and extracts a frequency (first frequency f ₁ ) in which the variance is smaller than a predetermined value. Waveform generation unit generates a first sound wave information of the frequency f ₁ of the first frequency extraction unit has extracted. Speaker outputs the sound wave of at least audible frequency band, and outputs the first sound wave frequency f ₁ based on the sound wave information wave generating unit has generated.

The sound volume measurement unit, the FFT analysis unit, the first frequency extraction unit, and the waveform generation unit constitute a distance measurement device. The distance measurement device performs an FFT analysis of a sound wave input from a microphone that collects at least a sound wave in an audible frequency band, and calculates a variance of a sound pressure level of each frequency using the analysis result. The distance measurement device extracts a frequency (first frequency f ₁ ) whose variance is smaller than a predetermined value, and generates sound wave information of the extracted first frequency f ₁ . The distance measuring apparatus outputs the generated first sound wave information of the frequency f ₁ and the speaker.

  The first frequency extraction unit calculates the variance of the sound pressure level of each frequency as a representative value using the time series data of the frequency spectrum generated by the FFT analysis unit. The first frequency extraction unit extracts a first frequency having a variance smaller than a predetermined value determined by the measurement accuracy of the distance measurement and an output value of the speaker as a measurement frequency, and outputs the extracted first frequency to the waveform generation unit.

  The waveform generator generates sound wave information including a sound pressure level of the sound wave of the first frequency extracted by the first frequency extractor, and outputs the generated sound wave information of the sound wave of the first frequency to the speaker. The waveform generator outputs the sound pressure level of the sound wave of the first frequency output from the speaker to the distance calculator.

  The distance calculation unit records the sound pressure level of the first frequency sound wave output from the speaker, and acquires the sound pressure level of the reflected wave of the first frequency sound wave output from the speaker. The distance calculation unit calculates the attenuation rate by dividing the sound pressure level of the reflected wave of the first frequency sound wave by the sound pressure level of the first frequency sound wave, and calculates a correlation between the attenuation rate and the distance obtained in advance. The distance to the measurement object is calculated using the relationship.

  Further, the measurement device of the present embodiment includes a volume measurement unit that measures the volume of a sound wave collected by the microphone, and a display unit that displays the distance calculated by the distance calculation unit. For example, the display unit displays the volume measured by the volume measurement unit.

  Further, the measuring device of the present embodiment includes a microphone that collects sound waves in the audible frequency band, and a speaker that outputs sound waves based on sound wave information of the sound waves of the measurement frequency output by the waveform generation unit.

  The measurement device of the present embodiment extracts the first frequency in which the variance of the sound pressure level per a certain time period is smaller than a predetermined value in a noise environment generated by the equipment. The measurement device of the present embodiment outputs the extracted first-frequency sound wave toward the measurement target, and collects the returned first-frequency sound wave. The measuring device of the present embodiment obtains the attenuation rate from the difference between the sound pressure level of the first frequency at the time of output and the sound pressure level of the first frequency at the time of sound collection, and measures with the own device based on the attenuation rate. Calculate the distance to the object.

  According to the measuring device of the present embodiment, the environmental noise and the sound wave to be measured are extracted by extracting the sound wave of the first frequency in which the amount of change in the sound pressure level per predetermined time is smaller than a predetermined value in the environmental noise. Interference can be minimized. Therefore, according to the measuring device of the present embodiment, it is possible to detect a change in the sound wave in the frequency band in the audible region.

  According to the present embodiment, without using ultrasonic waves, a microphone capable of collecting sound waves in the audible frequency band, and by adding a speaker capable of outputting sound waves in the audible frequency band, the noise value measurement device Can add a distance measurement function. Therefore, according to the present embodiment, even if the distance measuring function is added to the noise value measuring device, cost increase can be suppressed without losing the convenience of carrying.

  The measuring device according to the present embodiment can be used for measuring the distance from a measurement target at the time of noise inspection or abnormal noise inspection of facility equipment. According to the present embodiment, the measuring device can be arranged at the reference measurement distance from the object to be measured without physically measuring the reference measurement distance when measuring the noise value. The process of sound inspection can be simplified. The measuring device of the present embodiment can also be used for measuring the distance between a general object and a measuring device.

(Second embodiment)
Next, a measuring device according to a second embodiment of the present invention will be described with reference to the drawings. The measuring device of the present embodiment extracts a frequency (also referred to as a second frequency) in which the maximum value of the sound pressure level per certain time is smaller than a predetermined value in a noise environment generated by the equipment. The measuring device of the present embodiment outputs the extracted sound wave of the second frequency toward the noise measurement target, and collects the returned sound wave of the same frequency. The measuring device of the present embodiment obtains a delay time from the difference between the output time and the detection time of the same frequency sound wave, and calculates the distance between the measuring object and the measuring device from the delay time.

(Constitution)
FIG. 10 is a block diagram illustrating an example of a configuration of the measurement device 2 according to the present embodiment. As shown in FIG. 10, the measurement device 2 includes a microphone 21, a volume measurement unit 22, an FFT analysis unit 23, a second frequency extraction unit 24, a waveform generation unit 25, a distance calculation unit 26, a speaker 27, and a display unit 28. . The FFT analysis unit 23, the second frequency extraction unit 24, the waveform generation unit 25, and the distance calculation unit 26 constitute a distance measurement device 20 (also referred to as a measurement device). The distance measuring device 20 may have a configuration independent of those components as long as it is connected to the microphone 21, the volume measuring unit 22, the speaker 27, and the display unit 28. The microphone 21, the volume measurement unit 22, the FFT analysis unit 23, the speaker 27, and the display unit 28 are the same as the corresponding configuration of the measurement device 1 according to the first embodiment. Therefore, hereinafter, the second frequency extraction unit 24, the waveform generation unit 25, and the distance calculation unit 26, which are different from the measurement device 1 of the first embodiment, will be mainly described.

The second frequency extracting unit 24 acquires an FFT analysis result from the FFT analyzing unit 23. Second frequency extracting section 24, based on the FFT analysis result acquired from the FFT analyzer 23, the maximum value of the sound pressure level minimum frequency to extract (hereinafter, second referred to as a frequency f _2). If the output characteristics of the speaker are constant, the smaller the maximum value of the sound pressure level, the higher the security. Therefore, in the present embodiment, the frequency (the second frequency f ₂ ) having the smallest sound pressure level is extracted.

The predetermined value for the maximum value of the sound pressure level is determined by the output value of the speaker 27, the sound pressure level detected by the microphone 21, and the safety factor. For example, if 出力 of the output value of the speaker 27 is set as the detection level of the microphone 21 and the safety factor is tripled, the following Expression 3 holds.
(Maximum value) ≦ (detection level) / (safety factor) = (output value) / 6 (3)
Second frequency extracting section 24, at least a waveform generating step to output a second frequency f ₂ extracted to the waveform generator 25. Note that the second frequency extracting section 24, if necessary, the second frequency f ₂ may be output to the waveform generator 25 at a distance calculation step.

The second frequency extraction unit 24, the distance calculation step, and outputs the detection time T _2, the second frequency f ₂ wave is detected by the microphone 21 to the distance calculation unit 26.

Waveform generating unit 25 obtains the second frequency f ₂ from the second frequency extracting section 24. Waveform generating unit 25 generates the second sound wave information of a frequency f ₂ obtained from the second frequency extracting section 24. The second sound wave information of a frequency f ₂ which waveform generating unit 25 generates, and a sound pressure level and the output time T ₁ of the sound wave to be output from the speaker 27. Waveform generating unit 25 outputs the generated second sound wave information of the frequency f ₂ to the speaker 27 and the distance calculation unit 26. The waveform generator 25 may be configured to output only the output time T ₁ in the second sound wave information of the frequency f ₂ to the distance calculation unit 26.

In the waveform generation stage, the distance calculation unit 26 acquires from the waveform generation unit 25 sound wave information including the output time T _{1 at} which the sound wave of the second frequency f ₂ is output from the speaker 27, and records the obtained output time T ₁ I do. The distance calculating unit 26, the distance calculation step, the detection time T _2, the sound waves of the second frequency f ₂ is detected by the microphone 21 is obtained from the second frequency extracting section 24, records a detection time T _2, obtained I do.

The distance calculating unit 26, following as shown in Equation 4, the measurement object and the measuring device by integrating the value and the sound velocity v obtained by subtracting the output time T ₁ from the detection time T ₂ of the second frequency f ₂ wave Then, the distance L to 2 is measured. The distance calculation unit 26 outputs the calculated distance to the measurement target to the display unit 28.
L = (T ₂ −T ₁ ) × v (4)
The above is the description of the configuration of the measuring device 2 of the present embodiment. The measuring device 2 shown in FIG. 10 is an example, and does not limit the configuration of the measuring device 2 of the present embodiment.

(motion)
Next, the operation of the measuring device 2 will be described with reference to the drawings. The outline of the operation of the measuring device 2 is the same as the outline of the operation of the measuring device 1 of the first embodiment (FIG. 6). The operation of the measuring device 2 is different from the measuring device 1 of the first embodiment in the content of the waveform generation process (step S12 in FIG. 6) and the distance measurement process (step S13 in FIG. 6), and the other operations are the first. This is the same as the embodiment. Therefore, the details of the waveform generation processing and the distance measurement processing will be described below.

[Waveform generation processing]
FIG. 11 is a flowchart illustrating a waveform generation process (step S12 in FIG. 6) for generating a sound wave used for distance measurement.

  In FIG. 11, first, the measuring device 2 collects a sound wave with the microphone 21 (step S221).

  Next, the measurement device 2 performs an FFT analysis on the collected sound waves to determine a sound pressure level for each frequency (step S222).

  Here, if the sampling data of all the frequency bands is not available (No in step S223), the process returns to step S221. The measuring device 2 repeats the processing of steps S221 to S223 until the sampling data of each frequency band is completed.

On the other hand, when the sampling data of all the frequency bands are available (Yes in step S223), the measuring device 2 analyzes the sampling data of each frequency band, and determines the frequency at which the maximum value of the sound pressure level is the minimum (hereinafter, the frequency is referred to as the “second”). 2 is referred to as a frequency f ₂₎ to extract (step S224).

Next, the measuring apparatus 2 generates the second frequency f ₂ of the acoustic wave (step S225). This is the end of the processing according to the flowchart in FIG.

  The above is the description of the waveform generation processing of the measurement device 2. Note that the processing in FIG. 11 is an example, and does not limit the waveform generation processing by the measurement device 2.

[Distance measurement processing]
FIG. 12 is a flowchart for explaining the process of measuring the distance to the measurement target (corresponding to step S13 in FIG. 6).

12, first, the measurement apparatus 2, the generated rectangular wave to output to the measurement object, records the output time T ₁ (step S231).

Next, the measuring device 2, for collecting the second sound waves of frequency f ₂ returning from the direction of the measurement target (step S232).

Next, the measuring apparatus 2, sound waves of the sound pressure level of the second frequency f ₂ detects the detection time T _2, which exceeds the detection level (step S233).

Next, the measuring device 2 divides the delay time (T ₂ −T ₁ ) of the sound wave by the sound velocity v to calculate the distance between the measurement object and the own device (step S234).

  Then, the measuring device 2 displays the calculated distance (Step S235).

  The above is the description of the distance measurement processing by the measurement device 2 of the present embodiment. Note that the processing in FIG. 12 is an example, and does not limit the distance measurement processing by the measurement device 2 of the present embodiment.

As described above, the measurement device according to the present embodiment includes the microphone, the volume measurement unit, the FFT analysis unit, the second frequency extraction unit, the waveform generation unit, the speaker, and the display unit. The microphone collects sound waves in at least the audible frequency band. The FFT analysis unit performs FFT analysis on sound waves collected by the microphone. The second frequency extraction unit calculates the maximum value of the sound pressure level of each frequency using the result of the FFT analysis performed by the FFT analysis unit, and extracts a frequency (second frequency f ₂ ) whose maximum value is smaller than a predetermined value. Waveform generation unit generates a second sound wave information of the frequency f ₂ by the second frequency extracting portion is extracted. Speaker outputs the sound wave of at least audible frequency band, and outputs the second sound waves of frequency f ₂ based on the sound wave information wave generating unit has generated.

The sound volume measurement unit, the FFT analysis unit, the second frequency extraction unit, and the waveform generation unit constitute a distance measurement device. The distance measurement device performs an FFT analysis of a sound wave input from a microphone that collects at least a sound wave in an audible frequency band, and calculates a variance of a sound pressure level of each frequency using the analysis result. The distance measuring device extracts a frequency (second frequency f ₂ ) whose variance is smaller than a predetermined value, and generates sound wave information of the extracted second frequency f ₂ . The distance measuring device outputs the generated second sound wave information of the frequency f ₂ to the speaker.

  The second frequency extraction unit calculates the maximum value of the sound pressure level of each frequency as a representative value using the time series data of the frequency spectrum generated by the FFT analysis unit. The second frequency extracting unit extracts a second frequency whose calculated maximum value is smaller than a predetermined value as a measurement frequency, and outputs the extracted second frequency to the waveform generating unit. For example, the frequency extraction unit uses a value determined by the output value of the speaker, the sound pressure level of the sound wave detected by the microphone, and the safety factor as the predetermined value.

  The waveform generator generates sound wave information including the sound pressure level of the sound wave of the second frequency extracted by the frequency extractor. The waveform generator outputs the generated sound wave information of the sound wave of the second frequency to the speaker, and outputs an output time at which the sound pressure level of the sound wave of the second frequency is output from the speaker to the distance calculator.

  The distance calculation unit records the output time at which the sound pressure level of the second frequency sound wave was output from the speaker, and acquires the detection time at which the reflected wave of the second frequency sound wave output from the speaker was detected by the microphone. . The distance calculation unit calculates the distance to the measurement target by integrating the value obtained by subtracting the output time from the detection time and the sound speed.

  The measuring device of the present embodiment extracts the second frequency at which the maximum value of the sound pressure level per certain time period is smaller than a predetermined value under a noise environment generated by the equipment. The measuring device outputs the extracted second-frequency sound wave toward the measurement target, and collects the returned second-frequency sound wave. The measuring device calculates the delay time from the difference between the detection time of the sound wave of the second frequency and the output time of the sound wave of the second frequency, and divides the calculated time by the speed of sound so that the measuring device and the object to be measured can communicate with each other. Calculate the distance.

  According to the measurement device of the present embodiment, the environmental noise and the sound wave to be measured are extracted by extracting the sound wave of the second frequency in which the maximum value of the sound pressure level per a certain time period is smaller than a predetermined value in the environmental noise. Interference can be minimized. Therefore, according to the measuring device of the present embodiment, it is possible to detect a change in the sound wave in the frequency band in the audible region.

  According to the present embodiment, without using ultrasonic waves, a microphone capable of collecting sound waves in the audible frequency band, and by adding a speaker capable of outputting sound waves in the audible frequency band, the noise value measurement device Can add a distance measurement function. Therefore, according to the present embodiment, even if the distance measuring function is added to the noise value measuring device, cost increase can be suppressed without losing the convenience of carrying.

(Third embodiment)
Next, a distance measuring device (also referred to as a measuring device) according to a third embodiment of the present invention will be described with reference to the drawings. The distance measuring device according to the present embodiment is a high-level concept of the distance measuring device included in the measuring devices according to the first and second embodiments.

  As shown in FIG. 13, the distance measurement device 30 of the present embodiment includes an analysis unit 33, a frequency extraction unit 34, a waveform generation unit 35, and a distance calculation unit 36. The distance measurement device 30 is connected to the microphone 31, the speaker 37, and the display unit 38. The microphone 31, the speaker 37, and the display unit 38 are the same as the corresponding configuration of the first embodiment.

  The analysis unit 33 samples sound waves in the audible frequency band from the microphone 31 for a certain period of time. The analysis unit 33 generates time-series data of a frequency spectrum by performing FFT analysis on the sampled sound waves. The analysis unit 33 outputs the generated time-series data of the frequency spectrum to the frequency extraction unit 34 as an FFT analysis result.

  The frequency extracting unit 34 acquires an FFT analysis result from the analyzing unit 33. The frequency extracting unit 34 calculates a representative value of the sound pressure level of each frequency based on the FFT analysis result obtained from the analyzing unit 33. For example, the frequency extracting unit 34 calculates a variance or a maximum value as a representative value of the sound pressure level. Note that the representative value of the sound pressure level calculated by the frequency extracting unit 34 is not limited to the variance or the maximum value. The frequency extracting unit 34 extracts a frequency (also referred to as a measurement frequency) at which the representative value of the sound pressure level of each frequency is smaller than a predetermined value.

  The frequency extracting unit 34 outputs the extracted measurement frequency to the waveform generating unit 35 at least in a waveform generating stage. Note that the frequency extracting unit 34 may output the measured frequency to the waveform generating unit 35 at the distance calculation stage, if necessary. In at least one of the waveform generation stage and the distance calculation stage, the frequency extraction unit 34 outputs the sound wave information of the measurement frequency to the distance calculation unit 36. The sound wave information of the measurement frequency output from the frequency extraction unit 34 to the distance calculation unit 36 includes at least one of the sound pressure level of the sound wave of the measurement frequency measured by the microphone 31 and the detection time.

  The waveform generator 35 acquires the measurement frequency from the frequency extractor 34. The waveform generator 35 generates sound wave information of the measurement frequency acquired from the frequency extractor 34. The sound wave information of the measurement frequency generated by the waveform generation unit 35 includes at least one of the sound pressure level of the sound wave of the measurement frequency output from the speaker 37 and the output time. The waveform generator 35 outputs the generated sound wave information of the measurement frequency to the speaker 37 and the distance calculator 36.

  The distance calculation unit 36 acquires the sound wave information of the measurement frequency from the waveform generation unit 35 in the waveform calculation stage. In addition, the distance calculation unit 36 acquires the sound wave information of the sound wave of the measurement frequency from the frequency extraction unit 34 in the distance calculation stage. The distance calculation unit 36 calculates the distance to the measurement object using the sound wave information of the sound wave of the measurement frequency obtained from the frequency extraction unit 34 and the sound wave information of the measurement frequency obtained from the waveform generation unit 35. The distance calculation unit 36 outputs the calculated distance to the measurement target to the display unit 38. The distance to the measurement target calculated by the distance calculation unit 36 corresponds to the distance between the surface formed by the diaphragm of the microphone 31 and the speaker 37 and the measurement target.

  In this embodiment, since the distance measurement is mainly performed, only the measured distance to the object to be measured need be displayed on the display unit 38. Note that the information displayed on the display unit 38 is not limited to the measurement distance to the measurement target, and can be set arbitrarily.

  The above is the description of the configuration of the distance measurement device 30 of the present embodiment. The distance measuring device 30 shown in FIG. 13 is an example, and does not limit the configuration of the distance measuring device 30 of the present embodiment.

  As described above, the distance measurement device of the present embodiment measures the distance to the measurement target by collecting the reflected wave of the sound wave output from the speaker toward the measurement target using the microphone. The distance measurement device according to the present embodiment includes an analysis unit, a frequency extraction unit, a waveform generation unit, and a distance calculation unit. The analysis unit generates a time series data of a frequency spectrum by sampling a sound wave in an audible frequency band collected by the microphone for a certain period of time and analyzing the sampled sound wave using a fast Fourier transform process. The frequency extracting unit calculates a representative value of the sound pressure level of each frequency using the time-series data of the frequency spectrum generated by the analyzing unit, and extracts a measurement frequency based on the calculated representative value. The waveform generation unit generates sound wave information of the sound wave of the measurement frequency extracted by the frequency extraction unit, and outputs the generated sound wave information of the sound wave of the measurement frequency to the speaker. The distance calculation unit acquires the sound wave information of the sound wave of the measurement frequency generated by the waveform generation unit, and also acquires the sound wave information of the reflected wave of the sound wave of the measurement frequency output from the speaker. The distance calculating unit calculates the distance to the measurement target using the acquired sound wave information of the reflected wave of the measurement frequency sound wave and the sound wave information of the measurement frequency sound wave.

  According to the distance measuring device of the present embodiment, distance measurement using sound waves in the frequency band in the audible range is possible in a noise environment.

(hardware)
Here, a hardware configuration for executing the processing of the distance measurement device according to each embodiment of the present invention will be described using the information processing device 90 in FIG. 14 as an example. Note that the information processing device 90 in FIG. 14 is a configuration example for executing the processing of the distance measurement device of each embodiment, and does not limit the scope of the present invention.

  As shown in FIG. 14, the information processing device 90 includes a processor 91, a main storage device 92, an auxiliary storage device 93, an input / output interface 95, and a communication interface 96. In FIG. 14, the interface is abbreviated as I / F (Interface). The processor 91, the main storage device 92, the auxiliary storage device 93, the input / output interface 95, and the communication interface 96 are connected to each other via a bus 99 so as to be able to perform data communication. In addition, the processor 91, the main storage device 92, the auxiliary storage device 93, and the input / output interface 95 are connected to a network such as the Internet or an intranet via a communication interface 96.

  The processor 91 expands the program stored in the auxiliary storage device 93 or the like into the main storage device 92 and executes the expanded program. In the present embodiment, a configuration using a software program installed in the information processing apparatus 90 may be used. The processor 91 executes processing by the distance measuring device according to the present embodiment.

  The main storage device 92 has an area where programs are loaded. The main storage device 92 may be a volatile memory such as a DRAM (Dynamic Random Access Memory). Further, a nonvolatile memory such as an MRAM (Magnetoresistive Random Access Memory) may be configured and added as the main storage device 92.

  The auxiliary storage device 93 stores various data. The auxiliary storage device 93 is configured by a local disk such as a hard disk or a flash memory. In addition, various data may be stored in the main storage device 92, and the auxiliary storage device 93 may be omitted.

  The input / output interface 95 is an interface for connecting the information processing device 90 and peripheral devices. The communication interface 96 is an interface for connecting to an external system or device via a network such as the Internet or an intranet based on standards and specifications. The input / output interface 95 and the communication interface 96 may be shared as an interface for connecting to an external device.

  The information processing device 90 may be configured to connect input devices such as a keyboard, a mouse, and a touch panel as needed. These input devices are used for inputting information and settings. When a touch panel is used as an input device, the display screen of the display device may be configured to also serve as an interface of the input device. Data communication between the processor 91 and the input device may be mediated by the input / output interface 95.

  The information processing device 90 may be provided with a display device for displaying information. When a display device is provided, the information processing device 90 preferably includes a display control device (not shown) for controlling display on the display device. The display device may be connected to the information processing device 90 via the input / output interface 95.

  Further, the information processing device 90 may be provided with a disk drive as necessary. The disk drive is connected to the bus 99. The disk drive mediates between the processor 91 and a recording medium (program recording medium) not shown, such as reading of a data program from the recording medium and writing of a processing result of the information processing device 90 to the recording medium. The recording medium can be realized by an optical recording medium such as a CD (Compact Disc) and a DVD (Digital Versatile Disc). Further, the recording medium may be realized by a semiconductor recording medium such as a USB (Universal Serial Bus) memory or an SD (Secure Digital) card, a magnetic recording medium such as a flexible disk, or another recording medium.

  The above is an example of the hardware configuration for enabling the distance measurement device according to each embodiment of the present invention. Note that the hardware configuration in FIG. 14 is an example of a hardware configuration for executing arithmetic processing of the distance measurement device according to each embodiment, and does not limit the scope of the present invention. Further, a program that causes a computer to execute the process related to the distance measurement device according to each embodiment is also included in the scope of the present invention. Further, a program recording medium on which a program according to each embodiment is recorded is also included in the scope of the present invention.

  The components of the distance measuring device of each embodiment can be arbitrarily combined. Also, the components of the distance measuring device of each embodiment may be realized by software or may be realized by a circuit.

  As described above, the present invention has been described with reference to the exemplary embodiments. However, the present invention is not limited to the above exemplary embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

1, 2 Measuring device 10, 20, 30 Distance measuring device 11, 21, 31 Microphone 12, 22 Volume measuring unit 13, 23 FFT analyzing unit 14 First frequency extracting unit 15, 25, 35 Waveform generating unit 16, 26, 36 Distance calculation unit 17, 27, 37 Speaker 18, 28, 38 Display unit 24 Second frequency extraction unit 33 Analysis unit 34 Frequency extraction unit

Claims (10)

A distance measurement device that measures a distance to the measurement target by collecting a reflected wave of a sound wave output from a speaker toward the measurement target with a microphone,
Analysis means for sampling a sound wave in an audible frequency band collected by the microphone for a certain period of time, and generating time-series data of a frequency spectrum by analyzing the sampled sound wave using a fast Fourier transform process,
Frequency extraction means for calculating a representative value of the sound pressure level of each frequency using time-series data of the frequency spectrum generated by the analysis means, and extracting a measurement frequency based on the calculated value of the representative value,
Waveform generation means for generating sound wave information of sound waves of the measurement frequency extracted by the frequency extraction means, and outputting sound wave information of the generated sound waves of the measurement frequency to the speaker,
Acquiring the sound wave information of the sound wave of the measurement frequency generated by the waveform generating means, acquiring the sound wave information of the reflected wave of the sound wave of the measurement frequency output from the speaker, and acquiring the sound wave information of the acquired sound wave of the measurement frequency. A measuring device comprising: distance calculating means for calculating a distance to a measurement target using sound wave information of a reflected wave and sound wave information of sound waves of the measurement frequency. The frequency extracting means,
The variance of the sound pressure level of each frequency is calculated as the representative value using the time series data of the frequency spectrum generated by the analysis unit, and a predetermined value determined by the measurement accuracy of the distance measurement and the output value of the speaker is calculated. Also extract a first frequency having a small variance as the measurement frequency, and output the extracted first frequency to the waveform generation means,
The waveform generating means includes:
Generates sound wave information including the sound pressure level of the sound wave of the first frequency extracted by the frequency extracting means, and outputs sound wave information of the generated sound wave of the first frequency to the speaker, and is output from the speaker. Outputting the sound pressure level of the sound wave of the first frequency to the distance calculating means,
The distance calculating means,
The sound pressure level of the sound wave of the first frequency output from the speaker is recorded, the sound pressure level of the reflected wave of the sound wave of the first frequency output from the speaker is obtained, and the sound pressure level of the sound wave of the first frequency is obtained. An attenuation rate is calculated by dividing the sound pressure level of the reflected wave by the sound pressure level of the sound wave of the first frequency, and the measurement object is calculated using a correlation between the attenuation rate and the distance obtained in advance. The measuring device according to claim 1, which calculates a distance from the measuring device. The frequency extracting means,
The maximum value of the sound pressure level of each frequency is calculated as the representative value using the time series data of the frequency spectrum generated by the analysis means, and the second frequency whose calculated maximum value is smaller than a predetermined value is measured. Extracting as a frequency, outputting the extracted second frequency to the waveform generating means,
The waveform generating means includes:
Generates sound wave information including the sound pressure level of the sound wave of the second frequency extracted by the frequency extracting means, outputs the sound wave information of the sound wave of the second frequency generated to the speaker, and outputs the sound wave information from the speaker. Outputting the output time at which the sound pressure levels of the sound waves of the two frequencies are output to the distance calculating means;
The distance calculating means,
The output time at which the sound pressure level of the sound wave of the second frequency is output from the speaker is recorded, and the detection time at which the reflected wave of the sound wave of the second frequency output from the speaker is detected by the microphone is obtained. The measuring device according to claim 1, wherein a distance from the measurement target is calculated by integrating a value obtained by subtracting the output time from the detection time and a sound velocity. The frequency extracting means,
The measuring device according to claim 3, wherein a value determined by an output value of the speaker, a sound pressure level of a sound wave detected by the microphone, and a safety factor is used as the predetermined value.   The measuring device according to claim 1, further comprising a display unit that displays a distance calculated by the distance calculating unit.   The measuring device according to claim 1, further comprising a sound volume measuring unit that measures a sound volume of a sound wave collected by the microphone. Volume measurement means for measuring the volume of sound waves collected by the microphone,
The measuring device according to any one of claims 1 to 4, further comprising a display unit that displays a distance calculated by the distance calculating unit and a volume measured by the volume measuring unit. The microphone that collects sound waves in an audible frequency band,
The measuring device according to any one of claims 1 to 7, further comprising: the speaker that outputs a sound wave based on sound wave information of the sound wave of the measurement frequency output by the waveform generation unit. A measurement method for measuring a distance to the measurement target by collecting a reflected wave of a sound wave output from a speaker toward the measurement target with a microphone,
The information processing device is
Sampling sound waves in the audible frequency band collected by the microphone for a certain period of time,
Generate time-series data of the frequency spectrum by analyzing the sampled sound wave using the fast Fourier transform process,
Using the time series data of the generated frequency spectrum to calculate the representative value of the sound pressure level of each frequency,
Extract the measurement frequency based on the calculated value of the representative value,
Generate sound wave information of the sound wave of the extracted measurement frequency,
Output the sound wave information of the generated sound wave of the measurement frequency to the speaker,
Acquires sound wave information of a reflected wave of the sound wave of the measurement frequency output from the speaker,
A measurement method for calculating a distance to a measurement target using the acquired sound wave information of the reflected wave of the sound wave of the measurement frequency and the sound wave information of the sound wave of the measurement frequency. A program for measuring a distance to the measurement target by collecting a reflected wave of a sound wave output from a speaker toward the measurement target with a microphone,
A process of sampling a sound wave in an audible frequency band collected by the microphone for a certain period of time,
A process of generating time-series data of a frequency spectrum by analyzing the sampled sound wave using a fast Fourier transform process,
A process of calculating a representative value of the sound pressure level of each frequency using the generated time-series data of the frequency spectrum,
A process of extracting a measurement frequency based on the calculated value of the representative value,
A process of generating sound wave information of the sound wave of the extracted measurement frequency,
A process of outputting the generated sound wave information of the sound wave of the measurement frequency to the speaker,
A process of acquiring sound wave information of a reflected wave of the sound wave of the measurement frequency output from the speaker,
A program for causing a computer to execute a process of calculating a distance to an object to be measured using the acquired sound wave information of the reflected wave of the sound wave of the measurement frequency and the sound wave information of the sound wave of the measurement frequency.

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