JP2004212121A - Object sound detection method and device therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a detection method and a device therefor for a sound radiated from a specific acoustic radiation face of a measuring object in the state where the measuring object is ordinary used or operated. <P>SOLUTION: This object sound detection device for detecting the sound in an audio frequency zone radiated from the specific acoustic radiation face 10 of a vibrating object 9 is equipped with an ultrasonic radiation part 1 for radiating an ultrasonic wave toward the specific acoustic radiation face 10, a microphone 2 for detecting simultaneously the sound pressure of a reflected wave of the ultrasonic wave from the specific acoustic radiation face 10 and the sound pressure in an audio frequency zone near the specific acoustic radiation face 10, a high-pass filter 3 and a low-pass filter 4 for separating the sound pressure of the reflected wave of the ultrasonic wave detected by the microphone 2 from the sound pressure in the audio frequency zone, a frequency demodulator 5 for converting a frequency change by a Doppler shift of the reflected wave of the ultrasonic wave into a vibration speed of the specific acoustic radiation face 10, and a cross spectrum operation part 8 for operating a cross spectrum between the vibration speed and the sound pressure in the audio frequency zone. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a target sound detection method and apparatus for detecting only sound radiated from a specific acoustic radiation surface of a vibrating object.
[0002]
[Prior art]
Conventionally, sound intensity measurement by a two-microphone method is used to detect sound radiated from a specific acoustic radiation surface of a vibrating object. This is a method of approximating the air particle velocity vector and sound pressure from the sound pressure measured by two microphones installed at a certain distance, and calculating the vector quantity representing the acoustic energy passing through the space from the product. There is a method for detecting sound radiated from a specific acoustic radiation surface of an oscillating object by specifying a radiation surface radiating sound based on the magnitude and direction of the vector.
[0003]
[Problems to be solved by the invention]
However, when detecting sound radiated from a specific acoustic radiation surface of a vibrating object by acoustic intensity measurement by the two-microphone method, there are the following problems.
(1) Since all the acoustic energy passing through the space is measured, the acoustic energy of the sound radiated from the radiation surface other than the target specific radiation surface cannot be removed. Therefore, when the acoustic energy of the radiated sound from the specific radiation surface is equal to or smaller than the acoustic energy of the radiated sound from the other radiation surfaces, the radiated sound from the specific radiation surface cannot be detected.
(2) Since all the acoustic energy passing through the space is measured, the acoustic energy of the sound radiated from an object other than the target object cannot be removed. Therefore, when the acoustic energy of the radiated sound from the measurement target object is equal to or smaller than the acoustic energy of the radiated sound from the other objects, the radiated sound from the measurement target object cannot be detected.
(3) Since all the acoustic energy passing through the space is measured, it is impossible to remove the acoustic energy of the reflected sound that is propagated by reflecting the sound emitted from the target specific radiation surface by another object. Therefore, accurate acoustic energy of the radiated sound cannot be calculated, and an error occurs in specifying the radiating surface, so that the sound radiated from the specific acoustic radiating surface of the vibrating object cannot be detected.
(4) It is necessary to calculate the sound intensity at a number of points on the two-dimensional measurement plane at a certain distance from the radiation surface. In addition, in order to calculate the sound intensity of one point, a microphone and a microphone Two series of amplifiers and analyzers are required. Therefore, the cost for the measuring instrument increases as the number of measurement points increases.
[0004]
In order to solve these problems, it is necessary to install only the object to be measured in an anechoic room having high soundproof performance and measure the sound intensity. Therefore, the measurement object cannot be measured in the normal use state or operation state, and when multiple devices are used or operated in combination, the measurement for some of the devices is not possible. Impossible. Further, in order to reduce the cost for the measuring instrument, a great deal of work and time are required, such as measuring a large number of points in several times with a small number of microphones and analyzers.
[0005]
The present invention has been made in view of the above-described problems of the prior art, and the object of the present invention is to reduce the cost by simplifying the measurement system, so that the measurement object is normally used or operated. An object of the present invention is to provide a method and apparatus for detecting sound emitted from a specific acoustic radiation surface of a measurement object in a state where the object is measured.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 is a target sound detection method for detecting sound in an audible frequency range radiated from a specific acoustic radiation surface of a vibrating object, Radiating an ultrasonic wave toward the specific acoustic radiation surface, and simultaneously detecting a sound pressure of the reflected wave of the ultrasonic wave from the specific acoustic radiation surface and a sound pressure in an audible frequency range in the vicinity of the specific acoustic radiation surface, The frequency change due to the Doppler shift of the reflected wave is converted into the vibration velocity of the acoustic radiation surface, the cross spectrum between the vibration velocity and the sound pressure in the audible frequency range is calculated, and the sound radiated from the specific acoustic radiation surface is The audible sound radiated from the specific acoustic radiation surface by removing the reflected sound that is reflected and propagated by another object, the acoustic radiation surface other than the specific acoustic radiation surface, and the radiated sound from the object other than the vibrating object Detect only sound in the frequency range It was so.
[0007]
The invention according to claim 2 is a target sound detection device that detects sound in an audible frequency range radiated from a specific acoustic radiation surface of a vibrating object, and radiates an ultrasonic wave toward the specific acoustic radiation surface. And a sound detection means for simultaneously detecting the sound pressure of the reflected wave of the ultrasonic wave from the specific acoustic radiation surface and the sound pressure in the audible frequency range near the specific acoustic radiation surface, Separating means for separating the sound pressure of the reflected wave of the ultrasonic wave detected by the detecting means and the sound pressure in the audible frequency range, and the frequency change caused by Doppler shift of the reflected wave of the ultrasonic wave is caused to vibrate on the specific acoustic radiation surface. Conversion means for converting into speed and calculation means for calculating a cross spectrum between the vibration speed and the sound pressure in the audible frequency range are provided.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is a block diagram of the first embodiment of the target sound detection method and apparatus according to the present invention, and FIG. 2 is the second embodiment of the target sound detection method and apparatus according to the present invention. FIG. 3 is a block diagram of a third embodiment of the target sound detection method and apparatus according to the present invention.
[0009]
As shown in FIG. 1, the first embodiment of the target sound detection method and apparatus according to the present invention includes an ultrasonic radiation unit 1, a microphone 2, a high-pass filter 3, a low-pass filter 4, a frequency demodulator 5, A. / D converters 6 and 7 and a cross spectrum calculation unit 8.
[0010]
The ultrasonic radiation unit 1 includes a signal generator 1 a and an ultrasonic speaker 1 b, and the ultrasonic speaker 1 b is installed in the vicinity of the acoustic radiation surface 10 of the vibrating object 9 without contact. The signal generator 1a outputs a sine wave electric signal having a constant frequency and a constant amplitude in the ultrasonic frequency range. The ultrasonic speaker 1 b performs electroacoustic conversion on the sine wave electric signal output from the signal generator 1 a and radiates ultrasonic waves toward the acoustic radiation surface 10.
[0011]
The microphone 2 has the capability of simultaneously measuring the sound pressure of an ultrasonic wave reflected from a specific point on the acoustic radiation surface 10 and the sound pressure in the audible frequency range near the acoustic radiation surface 10. Convert and output analog electrical signal.
[0012]
The high-pass filter 3 extracts and outputs only the analog electrical signal proportional to the sound pressure of the ultrasonic wave reflected from a specific point on the acoustic radiation surface 10 from the analog electrical signal output from the microphone 2.
[0013]
The low-pass filter 4 separates and extracts and outputs only the analog electrical signal proportional to the sound pressure in the audible frequency range near the acoustic radiation surface 10 from the analog electrical signal output by the microphone 2.
[0014]
The frequency demodulator 5 converts the frequency change of the analog electrical signal output from the high-pass filter 3 into a voltage change, and outputs the analog electrical signal.
The A / D converters 6 and 7 convert the analog electrical signal output from the frequency demodulator 5 and the analog electrical signal output from the low-pass filter 4 into digital signals at certain time intervals.
[0015]
The cross spectrum calculation unit 8 calculates a cross spectrum between the digital signal output from the A / D converter 6 related to the sound pressure of the ultrasonic wave and the digital signal output from the A / D converter 7 related to the sound pressure in the audible frequency range. To do.
[0016]
The operation of the first embodiment of the target sound detection method and apparatus according to the present invention configured as described above will be described.
The ultrasonic speaker 1 b performs electroacoustic conversion on a sinusoidal electric signal having a constant amplitude and a constant frequency in the ultrasonic frequency range generated by the signal generator 1 a and radiates ultrasonic waves toward the acoustic radiation surface 10. At this time, the frequency of the ultrasonic wave reflected from a specific point on the acoustic radiation surface 10 changes in proportion to the vibration speed of the specific point on the acoustic radiation surface 10 due to the Doppler effect.
[0017]
The microphone 2 simultaneously measures the sound pressure of the ultrasonic wave reflected from a specific point on the acoustic radiation surface 10 and the sound pressure in the audible frequency range in the vicinity of the acoustic radiation surface 10, and acoustoelectrically converts them to convert an analog electrical signal. Output.
Next, the high-pass filter 3 separates and extracts an analog electrical signal proportional to the sound pressure of the ultrasonic wave reflected from a specific point on the acoustic radiation surface 10 out of the analog electrical signal output from the microphone 2 and outputs it. .
[0018]
The frequency demodulator 5 converts the frequency change of the analog electrical signal output from the high-pass filter 3 into a voltage change, and outputs the analog electrical signal. At this time, the analog electrical signal from the frequency demodulator 5 is proportional to the vibration speed at a specific point on the acoustic radiation surface 10. Further, the analog electrical signal output from the frequency demodulator 5 is converted into a digital signal at a certain time interval by the A / D converter 6.
[0019]
At the same time, the low-pass filter 4 separates and extracts an analog electrical signal proportional to the sound pressure in the audible frequency range near the acoustic radiation surface 10 from the analog electrical signal output from the microphone 2. The analog electrical signal output from the low-pass filter 4 is converted into a digital signal at a certain time interval by the A / D converter 7.
[0020]
Next, in the cross spectrum calculation unit 8, a digital signal proportional to the vibration velocity at one point of the acoustic radiation surface 10 to be measured in the vibrating object 9 and a digital signal proportional to the sound pressure in the audible frequency region in the vicinity thereof. Is calculated. As a result, among the spectral components included in the voltage value proportional to the sound pressure in the audible frequency range, the spectral components not included in the voltage value proportional to the vibration speed are removed.
[0021]
Further, since the measurement is performed in the vicinity of the acoustic radiation surface 10 to be measured, the reflected sound that is radiated from the audible frequency range from the acoustic radiation surface 10 to be measured is reflected by other objects and propagated, and the measurement target Since there is a large time difference between the vibration velocity of the acoustic radiation surface 10, the reflected sound is removed during the cross spectrum calculation.
[0022]
Therefore, from the reflected sound in which the radiated sound in the audible frequency range from the acoustic radiation surface 10 to be measured is reflected and propagated to other objects, the radiation surface other than the acoustic radiation surface 10 to be measured, and the objects other than the vibrating object 9 It is possible to detect only the sound in the audible frequency range radiated by the vibration of the acoustic radiation surface 10 to be measured.
[0023]
In addition, it is possible to detect the vibration velocity at one point of the acoustic radiation surface 10 to be measured and the sound pressure in the vicinity of the audible frequency range with the single microphone 2.
[0024]
Next, as shown in FIG. 2, the second embodiment of the target sound detection method and apparatus according to the present invention includes an ultrasonic radiation unit 1, a microphone 2, an A / D converter 11, and a high-pass filter calculation unit. 12, a low-pass filter calculation unit 13, a frequency demodulation calculation unit 14, and a cross spectrum calculation unit 8.
[0025]
The A / D converter 11 converts the analog electrical signal output from the microphone 2 into a digital signal at a certain time interval. The high-pass filter calculation unit 12 separates and extracts a digital signal proportional to the sound pressure of the ultrasonic wave reflected from a specific point on the acoustic radiation surface 10 from the digital signal output from the A / D converter 11.
[0026]
In addition, the low-pass filter calculation unit 13 separates and extracts a digital signal proportional to the sound pressure in the audible frequency range near the acoustic radiation surface 10 from the digital signal output from the A / D converter 11. The frequency demodulation calculation unit 14 converts the digital signal proportional to the sound pressure of the ultrasonic wave processed by the high pass filter calculation unit 11 into a digital signal proportional to the change in frequency. In addition, description of the component of the same code | symbol as the code | symbol shown in FIG. 1 is abbreviate | omitted.
[0027]
According to the second embodiment of the target sound detection method and apparatus according to the present invention configured as described above, the high-pass filter calculation unit 12, the low-pass filter calculation unit 13, and the frequency demodulation calculation unit 14 are digital signal processing techniques. By realizing the above, it is possible to perform processing by one computer including the cross spectrum calculation unit 8, and the cost for the measuring instrument can be reduced.
[0028]
Next, in the third embodiment of the target sound detection method and apparatus according to the present invention, a plurality of microphones 2 are arranged around an ultrasonic speaker 1b as shown in FIG. With such a configuration, simultaneous measurement can be performed on a plurality of acoustic radiation surfaces 10 to be measured by one ultrasonic speaker 1b and the same number of microphones 2 as the number of measurement points.
[0029]
Since the configuration is the same as that of the first embodiment shown in FIG. 1 except that a plurality of microphones 2 are arranged around the ultrasonic speaker 1b, the components having the same reference numerals as those shown in FIG. Explanation of the constituent elements and explanation of the operation of the third embodiment are omitted.
[0030]
【The invention's effect】
As described above, according to the present invention, it is possible to specify a measurement object in a state in which the measurement object is normally used or operated without using an anechoic chamber having high sound insulation performance required by the prior art. Sound radiated from the acoustic radiation surface can be detected. In addition, it is possible to detect the vibration velocity at one point on the acoustic radiation surface to be measured among the vibrating objects and the sound pressure in the audible frequency range in the vicinity with a single microphone. Can be reduced.
[Brief description of the drawings]
FIG. 1 is a block diagram of a first embodiment of a target sound detection method and apparatus according to the present invention. FIG. 2 is a block diagram of a second embodiment of the target sound detection method and apparatus according to the present invention. FIG. 3 is a block diagram of a third embodiment of the target sound detection method and apparatus according to the present invention.
DESCRIPTION OF SYMBOLS 1 ... Ultrasonic radiation | emission part, 1a ... Signal generator, 1b ... Ultrasonic speaker, 2 ... Microphone, 3 ... High pass filter, 4 ... Low pass filter, 5 ... Frequency demodulator, 6, 7, 11 ... A / D converter , 8 ... cross spectrum calculation unit, 9 ... vibrating object, 10 ... acoustic radiation surface, 12 ... high pass filter calculation unit, 13 ... low pass filter calculation unit, 14 ... frequency demodulation calculation unit.

Claims (2)

A target sound detection method for detecting sound in an audible frequency range radiated from a specific acoustic radiation surface of a vibrating object, wherein an ultrasonic wave is radiated toward the specific acoustic radiation surface, and the specific acoustic radiation surface And simultaneously detecting the sound pressure of the reflected wave of the ultrasonic wave and the sound pressure in the audible frequency range in the vicinity of the specific sound emitting surface, and then changing the frequency due to the Doppler shift of the reflected wave of the ultrasonic wave on the sound emitting surface. Converting to a vibration speed, calculating a cross spectrum between the vibration speed and the sound pressure in the audible frequency range, the reflected sound from the specific acoustic radiation surface reflected by other objects and propagated, and An object characterized by detecting only sound in an audible frequency range radiated from the specific acoustic radiation surface by removing sound radiated from an acoustic radiation surface other than the specific acoustic radiation surface and an object other than the vibrating object. Sound detection method. A target sound detection device for detecting sound in an audible frequency range radiated from a specific acoustic radiation surface of a vibrating object, the ultrasonic radiation means for radiating ultrasonic waves toward the specific acoustic radiation surface, and Sound detection means for simultaneously detecting the sound pressure of the reflected wave of the ultrasonic wave from the specific acoustic radiation surface and the sound pressure in the audible frequency range near the specific acoustic radiation surface, and the ultrasonic wave detected by the sound detection means Separating means for separating the sound pressure of the reflected wave and the sound pressure in the audible frequency range, and a converting means for converting a frequency change due to Doppler shift of the reflected wave of the ultrasonic wave into a vibration velocity of the specific acoustic radiation surface; A target sound detection apparatus comprising a calculation means for calculating a cross spectrum between the vibration speed and a sound pressure in the audible frequency range.

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