JP2006189367A - Noise measuring instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily measure a noise where an influence of a specified background noise is removed. <P>SOLUTION: Filters 102a, 102b, 102c extract respectively prescribed bands of frequency components fa, fb, fc corresponding to the specified background noises, for example, a sound of a frog, a sound of an insect such as a cicada, and a watercut sound of a fish group, from an output sound signal SA of a microphone 101. Connection switches 103a, 103b, 103c respectively take out selectively one portion or the whole out of the frequency components fa, fb, fc. A measuring part 105 finds a sound pressure level of the noise, based on a sound signal SA' obtained by subtracting the frequency components taken out by the connection switches 103a, 103b, 103c from the sound signal SA. A user on-/off-operates the connection switches, for example, in a measuring point, to remove the background noise affecting the noise measurement, based on the background noise. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a noise measuring device that measures noise of, for example, a power plant or a substation. Specifically, according to the present invention, noise measurement without the influence of specific background noise can be easily performed by adopting a configuration in which a frequency component in a predetermined band corresponding to specific background noise can be selectively subtracted from the output sound signal of the microphone. The present invention relates to a noise measuring apparatus that can be used for the following.

  Noise is generated from turbines, boilers, generators and transformers in substations. Conventionally, in order to reduce this noise, measures such as the use of low noise equipment and the installation of a soundproof room have been taken.

  On the other hand, based on the environmental conservation agreement concluded with the power station and the administration, noise measurement is performed at day and night at the site boundary, and it is confirmed that it complies with the standard value. This reference value is a regulation value including background noise.

  Depending on the season, time, or time of day, noise measurement may result in background noise (eg, frog voice, cicada insect voice, fish draining sound, etc.) rather than noise from power plants, etc. The measurement value of noise sometimes exceeded the reference value.

  Patent Document 1 describes a technique for accurately measuring noise from a noise source, excluding the influence of background noise. This technique detects a frequency component having a low sound pressure level of background noise from each frequency component of a frequency spectrum of noise, and measures a component of the detected frequency among noises caused by a noise source to be measured. .

JP 2001-159559 A

  In the technique described in Patent Document 1 described above, all background noise is to be removed, and the sound pressure level of noise is simultaneously measured for each frequency at three or more measurement points at different distances from the noise source. Then, the distance attenuation amount for each frequency of the sound pressure level is obtained from the measured value, and the frequency component in which the logarithm of the distance attenuation amount for each frequency of the sound pressure level is proportional to the logarithm of the distance from the noise source is found. Therefore, a large-scale noise measurement system including a computer is required, and noise measurement excluding the influence of background noise cannot be easily performed.

  An object of the present invention is to make it possible to easily perform noise measurement excluding the influence of specific background noise.

  The noise measuring device according to the present invention is extracted by a microphone, a predetermined number of filters for extracting frequency components of a predetermined band corresponding to specific background noise from the output sound signal of the microphone, and the predetermined number of filters, respectively. Switch means for selectively extracting some or all of the frequency components, a subtractor for subtracting the frequency component selectively extracted by the switch means from the output sound signal of the microphone, and a sound signal output from the subtractor And a display for displaying the sound pressure level of the noise obtained by the measurement unit.

  In the present invention, the output audio signal of the microphone includes a frequency component of noise from the noise source and a frequency component of background noise (noise other than noise from the noise source). From the output sound signal of the microphone, frequency components in a predetermined band corresponding to specific background noise, for example, frog voice, cicada insect voice, fish draining sound, etc. are extracted by a predetermined number of filters, respectively. .

  Some or all of the frequency components extracted by the predetermined number of filters are selectively extracted by the switch means. In this case, it is determined by which filter the frequency component extracted is extracted by, for example, the user operating the switch unit based on the background noise at the measurement point. Thereby, it is possible to perform noise measurement excluding the influence of background noise selected by the user.

  Note that a switch control unit that detects the signal level of the frequency component extracted by a predetermined number of filters and controls the switch means so as to select only the frequency component equal to or higher than the predetermined level may be further provided. In this case, noise measurement excluding the influence of all background noises having a high sound pressure level among the background noises respectively corresponding to the predetermined number of filters can be performed without requiring the user's selection effort.

  By subtracting the frequency component extracted by the switch means from the output audio signal of the microphone, an audio signal from which the specific background noise frequency component has been removed is obtained. Then, the sound pressure level of the noise is obtained based on the sound signal, and the sound pressure level is displayed on the display. The sound pressure level of this noise is obtained by removing the influence of specific background noise.

  In this way, the frequency component of a predetermined band corresponding to specific background noise can be selectively subtracted from the output sound signal of the microphone. When there is specific background noise, the output sound signal of the microphone is used. A frequency component in a predetermined band corresponding to the specific background noise can be subtracted, and noise measurement excluding the influence of the specific background noise can be easily performed.

  In addition, the frequency component of the predetermined band corresponding to the specific background noise can be selectively subtracted from the output sound signal of the microphone. When there is no specific background noise, the specific sound frequency is determined from the output sound signal of the microphone. A frequency component in a predetermined band corresponding to background noise can be prevented from being subtracted, and a reduction in noise measurement accuracy due to removal of useless frequency components from the output voice signal of the microphone can be avoided.

  According to the present invention, the frequency component of a predetermined band corresponding to specific background noise can be selectively subtracted from the output sound signal of the microphone, and noise measurement excluding the influence of the specific background noise can be easily performed. Can be done.

  A first embodiment of the present invention will be described. FIG. 1 shows a configuration of a noise measuring apparatus 100 as the first embodiment. This noise measuring device 100 is used when measuring noise of a power plant or a substation.

  The noise measuring apparatus 100 includes a microphone 101, filters (band-pass filters) 102a to 102c, connection switches 103a to 103c, and a subtractor 104. The microphone 101 collects sound at the measurement point. Each of the filters 102a to 102c extracts a frequency component of a predetermined band corresponding to specific background noise from the output audio signal SA of the microphone 101.

  For example, the filter 102a extracts the frequency component fa in the Fb band of FIG. 2, for example, corresponding to the frog voice as background noise, and the filter 102b corresponds to the voice of a semi-insect insect, for example, as background noise. The frequency component fb of the Fc band 2 is extracted, and the filter 102c extracts the frequency component fc of the Fd band of FIG. 2, for example, corresponding to the draining sound of the school of fish as the background noise. Note that the Fa band in FIG. 2 indicates the main frequency band of noise in the power plant and substation.

  The connection switches 103a to 103c are for taking out the frequency components fa to fc respectively extracted by the filters 102a to 102c. These connection switches 103a to 103c constitute switch means, and these connection switches 103a to 103c can selectively extract part or all of the frequency components fa to fc extracted by the filters 102a to 102c, respectively. it can. The connection switches 103a to 103c are turned on / off by the user. Based on the background noise at the measurement point, the user turns on a connection switch connected to a filter that extracts a frequency component of a predetermined band corresponding to the background noise whose influence is desired to be removed, and turns off the other connection switches. .

  The subtracter 104 subtracts the frequency component selectively extracted by the connection switches 103a to 103c from the output audio signal SA of the microphone 101, and the frequency component of a predetermined band corresponding to a specific background noise from the output audio signal SA of the microphone 101. The audio signal SA ′ from which the is removed is obtained.

  In addition, the noise measurement device 100 includes a measurement unit 105 and a display 106. The measuring unit 105 obtains the sound pressure level of noise based on the audio signal SA ′ output from the subtractor 104. The display device 106 is composed of, for example, an LCD (Liquid Crystal Display) or the like, and displays the sound pressure level of noise obtained by the measurement unit 105.

The operation of the noise measurement apparatus 100 shown in FIG. 1 will be described.
The sound at the measurement point is collected by the microphone 101. The output audio signal SA from the microphone 101 is supplied to the subtracter 104. The output audio signal SA of the microphone 101 is supplied to the input side of the filters 102a to 102c. Each of the filters 102a to 102c extracts a frequency component of a predetermined band corresponding to a specific background noise.

  In this case, the filter 102a extracts the frequency component fa of the band Fb corresponding to the frog voice as background noise. Further, the filter 102b extracts the frequency component fb of the band Fc corresponding to the voice of insects such as cicada as background noise. Further, the filter 102c extracts the frequency component fc of the band Fd corresponding to the water draining sound of the school of fish as background noise.

  Part or all of the frequency components fa to fc extracted by the filters 102 a to 102 c are selectively extracted by the connection switches 103 a to 103 c and supplied to the subtractor 104. That is, when the connection switch 103 a is in the on state, the frequency component fa extracted by the filter 102 a is extracted and supplied to the subtracter 104. When the connection switch 103b is in the on state, the frequency component fb extracted by the filter 102b is extracted and supplied to the subtracter 104. Further, when the connection switch 103 c is in the ON state, the frequency component fc extracted by the filter 102 c is extracted and supplied to the subtracter 104.

  The subtracter 104 subtracts the frequency component extracted by the connection switches 103a to 103c from the output audio signal SA of the microphone 101, and removes the frequency component of a predetermined band corresponding to a specific background noise from the output audio signal SA of the microphone 101. The obtained audio signal SA ′ is acquired. In this case, when the connection switch 103a is in the ON state, the subtracter 104 obtains an audio signal SA ′ from which the frequency component fa of the band Fb corresponding to the frog voice has been removed from the output audio signal SA of the microphone 101. It is done. When the connection switch 103b is in the on state, the subtracter 104 outputs the audio signal SA ′ from which the frequency component fb of the band Fc corresponding to the voice of a semi-worm is removed from the output audio signal SA of the microphone 101. Is obtained. When the connection switch 103c is in the on state, the subtracter 104 obtains an audio signal SA ′ from which the frequency component fc of the band Fc corresponding to the drainage sound of the fish school has been removed from the output audio signal SA of the microphone 101. It is done.

  The audio signal SA ′ output from the subtractor 104 is supplied to the measurement unit 105, and the measurement unit 105 obtains the sound pressure level of the noise based on the audio signal SA ′. Then, the display data of the obtained sound pressure level is supplied to the display device 106, and the sound pressure level of the noise is displayed on the display device 106.

  According to the noise measuring apparatus 100 shown in FIG. 1, a frequency component fa of a predetermined band corresponding to specific background noise (frog voice, cicada insect voice, fish drainage sound) from the output audio signal SA of the microphone 101. ˜fc can be selectively subtracted, and when there is specific background noise, a frequency component of a predetermined band corresponding to the specific background noise can be subtracted from the output audio signal SA of the microphone 101. Therefore, it is possible to easily perform noise measurement excluding the influence of the specific background noise.

  That is, by turning on the connection switch 103a, the frequency component fa of the band Fb corresponding to the frog voice as background noise can be subtracted from the output voice signal SA of the microphone 101, and the influence of the frog voice is removed. Noise measurement can be performed easily. Further, by turning on the connection switch 103b, it is possible to subtract the frequency component fb of the band Fc corresponding to the insect voice such as a cicada as background noise from the output sound signal SA of the microphone 101. Noise measurement excluding influence can be easily performed. Further, by turning on the connection switch 103c, it is possible to subtract the frequency component fc of the band Fd corresponding to the drainage sound of the fish school as background noise from the output sound signal SA of the microphone 101, and the influence of the drainage sound of the fish school. This makes it easy to measure noise.

  Further, according to the noise measuring apparatus 100 shown in FIG. 1, the frequency in a predetermined band corresponding to specific background noise (frog voice, cicada voice, fish drainage sound) from the output audio signal SA of the microphone 101. The components fa to fc can be selectively subtracted, and when there is no specific background noise, a frequency component in a predetermined band corresponding to the specific background noise is not subtracted from the output audio signal SA of the microphone 101. Therefore, it is possible to avoid a decrease in the accuracy of noise measurement due to the removal of unnecessary frequency components from the output audio signal SA of the microphone 101.

  Although Fa in FIG. 2 indicates main bands of power plant and substation noise, frequency components of power plant and substation noise may extend to bands Fb, Fc, and Fd. In this case, the frequency components fa, fb, and fc extracted by the filters 102a, 102b, and 102c are used as the output audio signal of the microphone 101 without the background noise such as the voice of the frog, the voice of the insect such as a cicada, and the water draining sound of the school of fish. If it is subtracted from SA, a part of the frequency components constituting the noise of the power plant and substation will be removed, and the accuracy of noise measurement will be reduced.

  Next explained is the second embodiment of the invention. FIG. 3 shows the configuration of a noise measuring apparatus 100A as the second embodiment. 3, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The noise measuring device 100A includes a switch control unit 107. The switch control unit 107 detects the signal levels of the frequency components fa to fc extracted by the filters 102a to 102c, and controls on / off of the connection switches 103a to 103c so as to select only the frequency components above a predetermined level. To do.

  In this case, when the signal level of the frequency component fa extracted by the filter 102a is equal to or higher than a predetermined level, the connection switch 103a is turned on and the frequency component fa is supplied to the subtractor 104. When the signal level of the frequency component fb extracted by the filter 102b is equal to or higher than a predetermined level, the connection switch 103b is turned on, and this frequency component fb is supplied to the subtractor 104. When the signal level of the frequency component fc extracted by the filter 102c is equal to or higher than a predetermined level, the connection switch 103c is turned on, and this frequency component fc is supplied to the subtractor 104.

  The rest of the noise measurement device 100A is configured in the same manner as the noise measurement device 100 shown in FIG. 1 and operates in the same manner.

  According to the noise measurement device 100A shown in FIG. 3, the on / off of the connection switches 103a to 103c is controlled according to the signal levels of the frequency components fa to fc extracted by the filters 102a to 102c, respectively. Therefore, the frequency component corresponding to the background noise with a high sound pressure level is automatically selected without the user selecting the frequency component to be subtracted from the output audio signal SA by operating the connection switches 103a to 103c, and the microphone 101 is selected. Is subtracted from the output audio signal SA. Therefore, the noise measurement excluding the influence of all the background noises having a high sound pressure level among the background noises (frog voice, cicada insect voice, fish draining sound) corresponding to the filters 102a to 102c can be performed by the user. This can be done without the need for selection.

  In the above-mentioned embodiment, it is for measuring the noise of a power plant or a substation, and as a background noise, a voice of a frog, a voice of a cicada or the like, and a draining sound of a school of fish are cited. However, the background noise to be removed is not limited to this. In this case, by providing a filter and connection switch corresponding to the number of types of background noise to be removed, noise measurement excluding the influence of specific background noise can be easily performed as in the above-described embodiment. .

  In the above-described embodiment, as shown in FIG. 2, the frequencies of the frog voice, the cicada insect voice, and the fish draining bands Fb, Fc, Fd increase in this order, and In the above description, the bands Fb, Fc, and Fd of FIG. However, this is merely an example, and the order of the respective bands may not be the order shown in FIG. 2, and there may be cases where a part of each band overlaps. Even in this case, the present invention is similarly applied. Of course you can.

  In the above-described embodiment, the filter 102a to 102c has a fixed extraction band. However, a part or all of the predetermined number of filters may be configured to vary the extraction band. In this case, the frequency band of the background noise specific to each measurement point is measured in advance, and the extraction band of the filter that can vary the extraction band can be adjusted to the frequency band of the measured background noise and used. The influence of the background noise inherent in can also be removed satisfactorily.

  The present invention can easily perform noise measurement excluding the influence of specific background noise, and can be applied, for example, when measuring noise in a power plant or substation.

It is a block diagram which shows the structure of the noise measuring device as 1st Embodiment. It is a figure which shows an example of the frequency band of noise and background noise. It is a block diagram which shows the structure of the noise measuring device as 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100,100A ... Noise measuring apparatus, 101 ... Microphone, 102a-102c ... Filter, 103a-103c ... Connection switch, 104 ... Subtractor, 105 ... Measuring part, 106 ... .Display, 107 ... Switch control unit

Claims (3)

A microphone,
A predetermined number of filters for extracting frequency components of a predetermined band corresponding to specific background noise from the output sound signal of the microphone;
Switch means for selectively extracting part or all of the frequency components respectively extracted by the predetermined number of filters;
A subtracter for subtracting the frequency component selectively extracted by the switch means from the output audio signal of the microphone;
A measurement unit for obtaining a sound pressure level of noise based on the audio signal output from the subtractor;
And a display for displaying a sound pressure level of the noise obtained by the measurement unit. The apparatus further comprises a switch control unit for detecting the signal level of each frequency component extracted by the predetermined number of filters and controlling the switch means so as to select only the frequency component equal to or higher than the predetermined level. The noise measuring device according to 1. The noise measuring device according to claim 1, wherein a part or all of the predetermined number of filters can vary an extraction band.

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