JP2014044081A - Noise monitoring system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a noise monitoring based on noise regulations to be performed while allowing a noise monitoring system to be down-sized, and to distinguish whether a cause of a noise is within a site or out of the site when its noise level exceeds a target value.SOLUTION: The present invention of a noise monitoring system 1 includes: a c-c microphone 12 and a noise meter 13 provided in a slave unit 11 arranged in the vicinity of a border of a site 2; and an arithmetic processing part 22 provided in a master unit 21 arranged in a construction business office 6 erected within the site 2. The arithmetic processing part comprises: an arrival angle calculation part 44 which calculates the arrival angle of a generated sound; an arrival frequency counting part 45 which counts the number of arrival generated sounds in a time width Δt for each arrival angle; and a noise evaluation part 46 which divides the number of arrivals N(θ) for each arrival angle by the total sum thereof to calculate an influence rate C(θ) for each arrival angle, and allocates noise levels L to angle-categorized noise levels Lover a prescribed angle range by using the influence rate C(θ) for each arrival angle.

Description

  The present invention relates to a noise monitoring system mainly used for noise monitoring at a construction site.

  At construction sites, various construction machines such as bulldozers, tractor excavators, and backhoes are operating on the premises, and various generated sounds including their operating noise propagate to the surroundings. If this measure is not taken, there is a concern that the above-mentioned generated sound will propagate to the surroundings and become noise, causing unexpected health damage or living damage to neighboring residents.

  For this reason, noise related to construction work is regulated based on the Noise Regulation Law, and noises due to construction work on the site must not exceed the regulation standards at the site boundary by setting target values as appropriate. I must.

  Under such circumstances, various technological developments have been conducted in the past to monitor noise associated with construction work.To take measures such as stopping construction machines when the target value is exceeded, It is necessary to specify the position of the sound source, and in order to do so, it is important to grasp the direction of arrival of the sound propagating from the sound source.

  Here, the sound propagating through the medium has its sound pressure and particle velocity as physical quantities, and their product corresponds to energy flowing in a unit area per unit time along the propagation direction. That is, if the sound intensity can be measured, since it is a vector quantity, it is possible to grasp the sound field including the sound arrival angle.

  Sound intensity measurement has been tried for a long time, but since it is difficult to measure the particle velocity accurately, it is separated along a predetermined direction using the fact that the inertial force and elastic force are equal in the equation of motion of sound waves. The so-called two-microphone method in which the particle velocity is obtained from the difference between the sound pressures at two points, and the sound intensity is approximately obtained by multiplying the particle velocity by the sound pressure (average value at two points) and taking the time average. (Pp method) is a typical calculation method for obtaining sound intensity (Patent Documents 1 to 3, Non-Patent Document 1).

JP 2003-111183 A JP 2011-13030 A JP 2011-27687 A International Publication No. 2009-153999 Pamphlet International Publication No. 2006-054599 Pamphlet JP 2008-249702 A

"Measurement of environmental noise and architectural acoustics" (Edited by the Acoustical Society of Japan, published by Corona, published on March 30, 2004, first edition) "Sound source search using sensitivity differences among multiple directional microphones" (Proceedings of the Acoustical Society of Japan, March 2006, pages 781 to 782) "Intensity measurement method based on Fourier series expansion of direction information of sound field" (acoustics of the Acoustical Society of Japan, September 2006, pages 721-722)

  However, in the pp method, the distance between the microphones is required for the calculation, so that it is required to accurately install the microphones, and the distance between the microphones becomes large in the low frequency range, and the apparatus is Due to the increase in size, there was a problem that there was a limit to the application to construction sites.

  On the other hand, unlike the pp method using an omnidirectional microphone, an acoustic intensity calculation method called a cc method using a directional microphone has been researched and developed. Since there is no need to adjust the distance between the microphones according to the target frequency, it is possible to expand the application by downsizing, and it is expected to spread widely in construction sites (Patent Documents 4 to 6, Non-Patent Documents). 2, 3).

  However, noise monitoring based on the Noise Regulation Law requires the use of a legal measuring instrument stipulated by the Measurement Law, that is, a sound level meter that has passed the verification. Therefore, in the cc method using a microphone having directivity, There was a problem that it was difficult to monitor noise based on the regulation law.

  In addition, in order to monitor noise caused by construction work, it is necessary to distinguish whether the noise is caused by sound generated on the site of construction work or sound generated outside the site that is not related to construction work. At some point, the noise level measured by the sound level meter reflects various generated sounds inside and outside the site.

  For this reason, even if a noise monitoring system using a sound level meter is adopted, when the measured noise level exceeds the target value, it cannot be distinguished whether the cause of the noise is on the premises or off the premises. As a result, there has been a problem that a long-time on-site monitoring system is required by workers.

  The present invention has been made in consideration of the above-described circumstances, and enables noise monitoring based on the Noise Regulation Law while enabling downsizing, and causes the noise when the noise level exceeds a target value. It is an object to provide a noise monitoring system that can identify whether it is inside or outside the site.

In order to achieve the above object, a noise monitoring system according to the present invention, as set forth in claim 1, is a plurality of sets of microphone pairs in which microphones having directivity are arranged so that the maximum sensitivity directions are opposite to each other. Sound pressure measuring means each configured to be arranged along a plurality of axes that are not parallel to each other and sandwich their origins;
A noise measuring means arranged in the vicinity of each microphone for measuring the sound pressure of the generated sound as a noise level;
A filter unit provided with an auditory correction circuit that filters the measurement value of each microphone with a frequency weighting characteristic substantially the same as the frequency weighting characteristic built in the noise measuring means;
An arrival angle calculation unit configured to calculate an arrival angle of the generated sound using output data from the filter unit;
An arrival frequency counting unit that counts the number of arrivals of the generated sound in a predetermined time width for each arrival angle using the arrival angle data obtained by the arrival angle calculation unit;
Dividing the number of arrivals for each arrival angle obtained by the arrival frequency counting unit by the sum of all directions to calculate the influence rate for each arrival angle, and using the influence rate and the noise level, And a noise evaluation unit that evaluates a noise index caused by the generated sound as a noise level for each angle.

Further, in the noise monitoring system according to the present invention, when the noise level is L and the sum of the influence rates over the predetermined angle range is C _T , the angle-specific noise level is L _T ,
L _T = L + 10 · logC _T (1)
The noise evaluation unit is configured to be calculated from

  In the noise monitoring system according to the present invention, the plurality of sets of microphones are set to two or three sets of microphones, and the plurality of axes are set to two or three axes orthogonal to each other.

  Further, in the noise monitoring system according to the present invention, the arrival angle calculation unit is configured such that the magnitude of energy of the generated sound is calculated as an energy value for each generated sound, and the arrival frequency counting unit is The number of arrivals of the generated sound is weighted by the energy value of the generated sound.

  The noise monitoring system according to the present invention is configured such that the sound pressure measuring unit and the noise measuring unit are installed near a boundary of a site where construction work is performed, and an angle range overlooking the site is the predetermined angle range. The noise evaluation unit is configured so that another noise level is calculated, and the angle-specific noise level is used as a site noise level.

  Further, the noise monitoring system according to the present invention is provided with a heavy machine selection circuit for filtering the measurement value by each microphone with a frequency characteristic according to the type of construction work machine in the site, in the filter unit, The noise level is set as the noise level in the heavy equipment separate site.

  Further, the noise monitoring system according to the present invention compares the level of the site noise level or the level of noise level by site of heavy machinery with a predetermined target value, and the level of noise level by site or level of noise level by site of heavy machinery is determined. An alarm generation unit that generates alarm data when the target value is exceeded, and an alarm output unit that outputs the alarm data generated by the alarm generation unit.

  In the noise monitoring system according to the present invention, the alarm output unit is provided in a construction machine that operates in the site.

  Of the sound intensity calculation methods, the cc method can maintain the microphone separation dimension constant regardless of the target frequency, and can therefore be miniaturized and widely used in construction sites. However, as described above, since the directional microphone is not a legal measuring instrument, noise monitoring according to the noise regulation law cannot be performed.

  As a result of research and development focusing on whether noise monitoring based on the noise regulation law can be performed using the cc method, the present applicant calculated the arrival angle of the generated sound in real time using the cc method, A novel invention in which the number of generated sound arrivals is calculated with a certain time width for each arrival angle, and then the noise level measured by the sound level meter is allocated to a predetermined angle range according to the calculated arrival number for each arrival angle. It has been done.

  That is, in the noise monitoring system according to the present invention, the sound pressure measuring means is configured by arranging a plurality of microphone pairs whose maximum sensitivity directions are opposite to each other along a plurality of axes and sandwiching their origins. In addition, the sound pressure of the generated sound is measured by each microphone, and the sound pressure of the generated sound is measured as a noise level by the noise measuring means separately from the sound pressure measurement by each microphone.

  Next, the measured value by each microphone is filtered by the A characteristic if the frequency weight characteristic substantially the same as the frequency weight characteristic built in the noise measuring means, for example, the frequency weight characteristic built in the noise measuring means is an A characteristic. After that, the arrival angle of the generated sound is calculated by the arrival angle calculation unit using the measured value.

  The arrival angle calculation unit may estimate the arrival angle by collating the difference value of the sound pressure measured by the microphone pair with the microphone sensitivity difference for each arrival angle stored in the storage unit in advance ( Patent Documents 4 and 5 and Non-Patent Document 2) Multiply the added value and difference value of the sound pressures measured by the microphone pair or calculate the difference value of the squared sound pressure, and then calculate the acoustic impedance ρc (ρ; air density) , C: velocity of sound) to calculate the sound intensity component along the arrangement axis of the microphone pair, and similarly calculate the sound intensity component along different axis directions using another microphone pair. Then, the arrival angle may be estimated from the vector components of the sound intensity (Patent Documents 4 and 6, Non-Patent Document 3).

  In calculating the arrival angle of the generated sound, for example, 0.1 seconds is set as the time width Δt, the generated sound is sampled at intervals of 0.001 seconds in each time width Δt, and the respective arrival angles are estimated as described above. It may be calculated by

  Next, the arrival frequency counting unit counts the number of arrivals of the generated sound in the time width Δt described above for each arrival angle using the arrival angle data obtained by the arrival angle calculation unit.

  When counting for each angle of arrival, if it is a two-dimensional plane, 360 ° of the entire circumference is divided into 10 °, for example, 0 ° to 10 °, 10 ° to 20 °, and so on. If the number of generated sound arrivals is counted for each width and grasped in a three-dimensional space, for example, the number of generated sound arrivals may be similarly counted for another two-dimensional plane orthogonal to the above-described two-dimensional plane.

Next, when the number of arrivals for each arrival angle θ obtained by the arrival frequency counting unit is N (θ) and the total sum related to θ is ΣN (θ),
C (θ) = N (θ) / ΣN (θ) (2)
To calculate C (θ). Where C (θ) is
0 ≦ C (θ) ≦ 1
It is.

  C (θ) is obtained by dividing the number of arrivals N (θ) of the generated sound for each arrival angle θ by the sum ΣN (θ), and for each arrival angle θ with respect to the arrival frequency of the generated sound from all directions. In the following, C (θ) is referred to as an influence rate. Note that θ is assumed to be handled as a value having a certain width such as 0 ° to 10 °, 10 ° to 20 °, etc. as described above for convenience of calculation processing. In the case where the angle of arrival does not change and the angle of arrival is constant, it is also included that it is treated as a value having substantially no width.

  The influence rate C (θ) is defined as the ratio of the arrival frequency for each angle of arrival θ with respect to the arrival frequency of the sound generated from all directions as described above. Therefore, the noise level is calculated using C (θ). By allocating, it is possible to evaluate a noise index caused by sound generated from a predetermined angle range.

For example, if C _T is the sum of C (θ) in the angle range θ _{1 to} θ ₂ , C (θ) (θ = θ _{1 to} θ ₂ ), the energy of the generated sound coming from all directions is expressed as E for convenience. When this is determined and multiplied by C _T , the multiplication result can be considered as the energy E _{T of the} generated sound coming from the predetermined angle range θ _{1 to} θ ₂ . That is,
E _T = E · C _T (3)
Here, when the reference value of the energy of the generated sound is E ₀ ,
E _T / E ₀ = E / E ₀ · C _T
So, taking the common logarithm of both sides and multiplying by 10,
10 · log (E _T / E ₀ ) = 10 · log (E / E ₀ ) + 10 · log C _T (4)
It becomes.

On the other hand, the noise level is the square of the sound pressure or the sound energy expressed in decibels. The first term on the right side of the equation (4) corresponds to this noise level. if you put the L _T,
L _T = L + 10 · logC _T (1)
It becomes.

Here, since the second term on the right side of the equation (1) takes zero or a negative value, L _T is a value smaller than the noise level L, and is noise caused by sound generated from a predetermined angle range. It can be considered an indicator.

The noise level in the prior art is a noise index based on the premise that the generated sound is measured in all directions using an omnidirectional microphone, and the noise cannot be grasped according to the difference in the arrival angle. On the other hand, in the present invention, the ratio of the arrival frequency for each angle of arrival θ with respect to the arrival frequency of the sound generated from all directions is calculated, and this is defined as the influence rate C (θ). by performing in example (1) calculation of the equation using the sum C _T of C (theta) in the angular range theta ₁ through? _2, to allocate the noise level L is omnidirectional in noise indices L _T for each angular range Is possible.

Since the noise indices due to sound generated from the predetermined angle range is not present in the prior art, hereinafter referred to L _T and each angle noise level, to be distinguished from the noise level L is omnidirectional .

Specifically, for example, 360 ° of the entire circumference is divided by 10 at 36 °, the number of arrivals of generated sound arriving during Δt in the angle range of 0 ° to 36 ° is 50, and the number of arrivals in other angle ranges is If a respective 5.55, incoming number for each arrival angle sum, that is, the incoming number is about 100 from all directions, 0 ° to 36 ° angle by the noise level in the angular range L _T is
L _T = L + 10 · log (50/100) ≈L−3
Each nine other generated sound coming from angle range affects each angle noise level L _T,
L _T = L + 10 · log (5.55 / 100) ≈L−12.6
Next, each angle noise level L _T is reduced by about 3dB or about 12.6dB, respectively than the noise level L.

Therefore, if the noise monitoring area, for example, the site where the construction work is performed is included in the angle range of 0 ° to 36 ° when viewed from the measurement point, the noise level L is not monitored but the noise is not monitored. sufficiently performed noise monitored using 3dB lower angle different noise levels L _T than the level.

  As described above, according to the noise monitoring system of the present invention, the noise level measured by the sound level meter is allocated as the noise level for each predetermined angle range according to the influence rate for each angle of arrival. Only the noise caused by the sound generated from the area will be monitored, and the sound generated from other than the monitored area, for example, noise from cars traveling on the surrounding roads will be excluded from the monitoring target. Compared to the conventional case where the noise level reflecting the generated sound is used, it is possible to monitor the noise more rationally at each stage.

  In the prior art, the noise level means a sound pressure level filtered by the A characteristic among the frequency weighting characteristics. However, in the present invention, not only the A characteristic but also other frequency weighting characteristics for audibility correction are included. In addition to being included, the same applies to the noise level for each angle, as well as the noise level inside the site and the noise level outside the site, which will be described later.

  The sound pressure measuring means is mainly assumed to have a configuration in which a plurality of microphone pairs are two or three microphone pairs and a plurality of axes are two or three axes orthogonal to each other. If it is sufficient to approximately grasp the angle of arrival of the generated sound on a plane, for example, a horizontal plane, two pairs of microphones may be installed along two axes extending in two directions in the horizontal plane. Absent. Further, in estimating the arrival angle from the vector component of the sound intensity, the plurality of axes do not necessarily have to be orthogonal, for example, along the four axes that respectively extend from the center of the regular tetrahedron toward the four vertices. By installing four pairs of microphones, it is possible to grasp the angle of arrival in a three-dimensional space.

  The microphone has a directivity such as a cardioid, a super cardioid, and a hyper cardioid, and the noise measuring means is composed of a certified sound level meter.

  As long as the arrival frequency of the generated sound is counted for each arrival angle, the configuration of the arrival frequency counting unit is arbitrary. For example, each time the generated sound arrives, the frequency may be simply counted. Is configured so that the magnitude of the energy of the generated sound is calculated as an energy value for each of the generated sounds, and the arrival frequency counting unit is configured so that the number of arrivals of the generated sounds is If it is configured to be weighted by the energy value of the generated sound, the influence rate and noise level by angle are also calculated in a form weighted by the energy value of the generated sound, so the influence on the noise is more dominant. It becomes possible to perform noise monitoring mainly on the generated sound.

  In the noise monitoring system according to the present invention, since the sound to be monitored is measured as the noise level in a state where the sound to be monitored is synthesized with the sound not to be monitored, it is not possible to take appropriate noise countermeasures for the monitoring target. It can be applied to the situation, for example, it is applied to production facilities where manufacturing machines such as metal processing machines, compressors, looms, and printing machines, which are subject to regulation by the Noise Regulation Law, are installed, and various construction sites be able to.

  When the noise monitoring system according to the present invention is applied to a construction site, the sound pressure measuring means and the noise measuring means may be installed at arbitrary locations within the site where the construction work is performed. Although the predetermined angle range for calculation may be arbitrarily set, the sound pressure measuring means and the noise measuring means are installed in the vicinity of the boundary of the site where the construction work is performed, and the angle range overlooking the site is If the noise evaluation unit is configured so as to be within a predetermined angle range, the noise level is the noise level by angle (hereinafter referred to as site noise level) caused by the sound generated inside the site and the occurrence occurring outside the site. The noise level is assigned to two noise levels (hereinafter referred to as off-site noise levels) caused by sound, and thus noise countermeasures can be performed more efficiently.

  Specifically, for example, if the site is rectangular and the sound pressure measuring means is installed near the corner, the predetermined angle range is 90 °, and it is also installed near the long side or short side edge. 180 degrees can be set.

  Here, if the filter unit is provided with a heavy equipment selection circuit that filters the measurement values by the microphones with frequency characteristics according to the type of construction machine on the site, the calculated noise level in the site is calculated. It is possible to easily identify which construction machine is caused by. Hereinafter, the site noise level corresponding to a specific construction machine is referred to as the heavy machinery specific site noise level.

  The noise level in each heavy equipment site is a new noise index filtered by the frequency weighting characteristic for selecting heavy equipment in addition to the frequency weighting characteristic for auditory correction, and is conventionally corrected by the A characteristic. The noise level is different.

  The heavy equipment sorting circuit is configured to correspond to a plurality of construction machines, and is configured to be switchable to which construction machine is to be filtered, and further adapted to construction machines. It is desirable that the frequency filtering should be switchable.

  It is arbitrary how the noise level in the site calculated by the above-mentioned procedure or the noise level in the site according to heavy machinery is used for noise monitoring. For example, the noise level in the site calculated over the entire day or the noise level in the site according to heavy machinery is used. After considering appropriate noise countermeasures based on this, the noise countermeasures may be reflected in the next day's construction work. However, the size of the noise level in the site or the noise level in each heavy machine is predetermined. An alarm creation unit that creates alarm data when the noise level in the site or the noise level in each heavy machinery exceeds the target value, and the alarm data created by the alarm creation unit is output. If an alarm output unit is provided, noise countermeasures can be taken in real time.

  Here, the configuration and location of the alarm output unit is arbitrary. For example, the screen is displayed on a computer installed in the construction office. Although it is possible to contact the construction machine operator, it is possible to further improve the immediateness of noise countermeasures if the alarm output unit is installed on the construction machine that operates on the premises. It becomes. In this case, the alarm output unit can be configured using, for example, a portable information terminal installed in the driver's seat.

It is a figure of the noise monitoring system which concerns on this embodiment, (a) is a whole block diagram, (b) is site layout drawing. The block diagram of cc microphone 12. FIG. The detailed block diagram of an arithmetic processing part. It is explanatory drawing of the noise monitoring system which concerns on this embodiment, (a) is a figure which showed a mode that the generated sound each arrived from the site 2 and the general road 4, (b) showed the sound intensity and its component. FIGS. 3C and 3D are diagrams showing the relationship between acoustic intensity and arrival angle. The graph which showed a mode that the number of arrivals of generated sound was counted for every angle of arrival.

  Embodiments of a noise monitoring system according to the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is an overall block diagram and a site layout diagram showing a noise monitoring system according to the present embodiment. As can be seen from the figure, the noise monitoring system 1 according to the present embodiment is applied to noise countermeasures for a construction machine 3 operating on a site 2 where construction work is performed, and is near the boundary of the site 2 The cc microphone 12 as sound pressure measuring means and the sound level meter 13 as noise measuring means provided in the slave unit 11 disposed between the site and the general road 4, and standing in the site 2 An arithmetic processing unit 22 provided in the master unit 21 disposed in the construction office 6 provided, and an alarm output unit 32 provided in the grandchild machine 31 installed in the construction machine 3 operating in the site 2 With.

  As shown in FIG. 2, the cc microphone 12 includes six microphones 12a to 12f having directivity, and among them, the microphones 12a and 12b, the microphones 12c and 12d, and the microphones 12e and 12f are respectively provided. The microphones are arranged so that the maximum sensitivity directions are opposite to each other, i.e., 0 ° and 180 °, to form three microphone pairs, and each microphone pair is divided into three axes orthogonal to each other, ie, x, y, z Each of the microphones 12a to 12f measures the sound pressure of the sound generated around the handset 11 (hereinafter referred to as generated sound). . The microphones 12a to 12f can be configured by microphones each having cardioid directional characteristics.

  The sound level meter 13 measures the sound pressure of the generated sound as a noise level, and may be appropriately selected from commercially available sound level meters that have passed the test. It is assumed that the sound level meter 13 has a built-in filter circuit having a frequency weighting characteristic that is widely used for measuring environmental noise.

  The cc microphone 12 and the sound level meter 13 include an amplifier 14 that amplifies the sound pressure value measured by the cc microphone 12, an A / D converter 15 that converts the sound pressure value into digital data, and the noise level measured by the sound level meter 13. An A / D converter 16 that converts the level into digital data and a transmitter 17 connected to the output side of the A / D converters 15 and 16 are installed inside a housing (not shown). It is desirable that such a housing has a configuration that is portable and takes weather resistance into consideration.

  On the other hand, the base unit 21 includes a receiving unit 23, a personal computer 24, and a transmitting unit 27 that receive transmission data wirelessly transmitted from the transmitting unit 17 of the slave unit 11, and the arithmetic processing unit 22 described above includes: The computer 24 includes hardware such as a CPU, a built-in hard disk, and memory, and software that operates on the hardware.

  The personal computer 24 includes an external hard disk 25 for reading out data necessary for the arithmetic processing in the arithmetic processing unit 22 or storing the result of arithmetic processing, and a monitor 26 for displaying the arithmetic processing result. It is provided.

  The alarm output unit 32 is configured by a portable information terminal attached to the driver's seat of the construction work machine 3.

  As shown in FIG. 3, the arithmetic processing unit 22 includes a filter unit 41 that filters a measurement value received by the cc microphone 12 received via the receiving unit 23, and the filter unit is built in the sound level meter 13. An auditory correction circuit 42 is provided that performs filtering with the same A characteristic as the frequency weighting characteristic.

  The arithmetic processing unit 22 further uses the output data from the filter unit 41 to calculate the arrival angle of the generated sound, and the time width Δt using the arrival angle data obtained by the arrival angle calculation unit. The arrival frequency counting unit 45 for counting the number of arrivals of the generated sound for each arrival angle, the arrival number N (θ) for each arrival angle obtained by the arrival frequency counting unit, and the reception unit 23 A noise evaluation unit 46 that evaluates noise using the noise level L of the sound level meter 13 is provided.

Here, the noise evaluation unit 46 calculates the influence rate C (θ) for each arrival angle by dividing the arrival number N (θ) for each arrival angle by the sum of all directions, and the influence rate for each arrival angle. The noise level L is assigned to each angle noise level using C (θ), and in this embodiment, it corresponds to the direction from the arbitrary position in the site 2 toward the cc microphone 12 of the slave unit 11. If the coordinate system has a right angle of 0 ° and a counterclockwise direction in the positive direction in FIG. The noise level for each angle is calculated with the angle ranges of ˜180 ° and 180 ° -360 °, respectively. Hereinafter, the noise level for each angle having an angle range of 0 ° to 180 ° is referred to as an in-site noise level L _I , and the noise level for an angle having an angle range of 180 ° to 360 ° is referred to as an off-site noise level L _O.

Arithmetic processing unit 22 is further compared with a predetermined target value the size of the on-site noise level L _I, be configured to alert data is created when該敷locations within the noise level exceeds the target value The alarm output unit 32 is configured to output the alarm data generated by the alarm generation unit.

  In order to monitor the noise caused by the construction machine 3 operating in the site 2 using the noise monitoring system 1 according to this embodiment, first, the sound pressure of the generated sound is measured as a noise level by the noise meter 13. .

  As shown in FIG. 4 (a), the generated sound is broadly divided into those caused by the construction machine 3 in the site 2 and those caused by the vehicle 5 traveling on the general road 4. , They are measured as noise levels in all directions in the synthesized state.

  On the other hand, while measuring the noise level with the sound level meter 13, the sound pressure of the generated sound is simultaneously measured with the cc microphone 12. In addition, the subunit | mobile_unit 11 shall be installed so that the x-axis of the cc microphone 12 may face the right direction of the figure, as shown to Fig.4 (a).

  Next, the sound pressure value measured by each of the microphones 12a to 12f is converted into a frequency domain by an FFT (not shown), and then filtered by the audibility correction circuit 42 of the filter unit 41, and then by an inverse FFT (not shown). After returning to the time domain, the arrival angle of the generated sound is calculated by the arrival angle calculation unit 44.

As shown in FIG. 4 (b), the arrival angle calculation unit 44 calculates the added value and the difference value from the sound pressures p ₁ and p ₂ measured by the microphone pair including the microphones 12a and 12b. formula,
(p ₁ + p ₂ ) ・ (p ₁ −p ₂ ) (3)
Or multiply them by the squared sound pressure difference value,
(p ₁ ² -p ₂ ² ) (4)
And then:
(p ₁ + p ₂ ) · (p ₁ −p ₂ ) / ρc (5)
Or
(p ₁ ² −p ₂ ² ) / ρc (6)
As shown by, by dividing by acoustic impedance ρc (ρ; air density, c; sound velocity), an acoustic intensity component I _x along the arrangement axis of the microphone pair, that is, the x axis is calculated.

Similarly, the sound intensity component I _y along the y-axis is calculated using the sound pressure measured by the microphone pair composed of the microphones 12c and 12d, and the sound pressure measured by the microphone pair composed of the microphones 12e and 12f. Is used to calculate the acoustic intensity component I _z along the z-axis.

Next, using the components I _x , I _y , and I _z of the sound intensity, the arrival angle θ is converted into the angle components θ _xy and x− on the _xy plane as shown in FIGS. Calculated as the angle component θ _xz in the z plane. Note that the angle component θ _{yz in the yz} plane may be used.

  In calculating the arrival angle θ of the generated sound, for example, 0.1 seconds is set as the time width Δt, and the generated sound is sampled at intervals of 0.001 seconds in each time width Δt, and the respective arrival angles θ are described above. Calculate by procedure.

  Next, the arrival frequency counting unit 45 counts the number of sound arrivals in the time width Δt described above for each arrival angle using the arrival angle data obtained by the arrival angle calculation unit 44.

  When counting for each angle of arrival, as shown in FIG. 5, the entire circumference is 360 ° (in the figure, for convenience, the left angle range is −180 ° to 0 °), for example, 0 ° to 10 °, It is divided into 10 ° increments of 10 ° to 20 ° (horizontal axis), and the number of generated sounds N (θ) is counted for each angular range (vertical axis).

  Note that the counting for each angle of arrival will be described assuming that the sound field is grasped on a two-dimensional plane for convenience of explanation, but when counting for each angle of arrival in a three-dimensional space, the angle of arrival is considered as a solid angle. Can be processed in the same way.

Next, the influence rate for each arrival angle is calculated by dividing the number of arrivals for each arrival angle obtained by the arrival frequency counting unit 45 by the sum of all directions. That is, if the number of arrivals for each arrival angle is N (θ), the influence rate C (θ) for each arrival angle is
C (θ) = N (θ) / ΣN (θ) (2)
ΣN (θ): Sum of N (θ) with respect to angle of arrival θ
It can be expressed as.

Next, the calculated influence rate C (θ) is summed in an angle range of 0 ° to 180 ° to obtain C _I. Here, C _I corresponds to the ratio of the area on the right side to the entire area in FIG.

Next, C _I is expressed by the following equation:
L _T = L + 10 · logC _T (1)
Substituted into the C _T, 0 ° to 180゜Wo angle range and angular-specific noise level, namely to calculate the on-site noise level L _I.

As a specific example, if C _I is 0.7, the in-site noise level L _I can be calculated from equation (1):
L _I = L + 10 · log (0.7)
= L-1.6
Becomes 1.6 dB lower than the noise level L.

Therefore, when monitoring the noise of the construction machine 3 operating on the site 2, the site noise level L _I lower by 1.6 dB than the noise level may be used instead of the noise level L.

Here, at the time of noise monitoring, the site noise level L _I is compared with a predetermined target value, and if the site noise level is lower than the target value, the operation of the construction machine 3 on the site 2 is performed. Continue as it is.

On the other hand, if the in-site noise level L _I is higher than the target value, the alarm generation unit 47 generates alarm data, and the grandchild machine 31 receives the alarm data and outputs it to the alarm output unit 32.

  The alarm output unit 32 is configured such that an alarm button blinks on the screen of the portable information terminal constituting the grandchild machine 31 or is displayed in an alarm color, or an alarm alarm is generated from the speaker of the portable information terminal. The alarm data generated by the alarm generation unit 47 may be appropriately generated according to the configuration of the alarm output unit 32.

Incidentally, if necessary, and C _O by summing the fraction affected C (theta) at 180 ° to 360 ° angular range, and assigns the C _T of C _O a (1) in the same manner as described above Thus, the noise level by angle with the angle range of 180 ° to 360 °, that is, the off-site noise level L _O may be calculated.

  As described above, according to the noise monitoring system 1 according to the present embodiment, the noise level measured by the sound level meter 13 is different for each predetermined angle range according to the influence rate C (θ) for each arrival angle. Since the noise level L (θ) is assigned, the target of noise monitoring is not the noise level reflecting all the generated sounds, but the noise level by angle, that is, the noise by angle reflecting only the generated sound from the monitoring target. Become a level.

  For this reason, the influence of the generated sound irrelevant to the monitoring target is eliminated, and thus more rational noise monitoring can be performed.

In particular, according to this embodiment, the entire circumference of 360 ° is divided into an angular range (0 ° to 180 °) overlooking the site 2 and other angular ranges, and the influence rate C (θ) in the former angular range. a C _I to summing, because to calculate the on-site noise level L _I using this, the child and the generated sound is measurement point in the general road 4 is a generated sound and off-site in the site 2 Therefore, the noise range can be appropriately and efficiently taken into consideration.

In addition, according to the noise monitoring system 1 according to the present embodiment, when the site noise level L _I exceeds the target value, the alarm generation unit 47 generates alarm data, and the alarm data is transmitted to the grandchild machine 31 side. Since it is received and output to the alarm output unit 32, it is possible to take noise countermeasures for the construction machine 3 in the site 2 in real time.

  Although not specifically mentioned in the present embodiment, in addition to the audibility correction circuit 42, the filter unit 41 is provided with a heavy machinery selection circuit that performs filtering with the frequency characteristic of the generated sound corresponding to the type of the construction machine 3. Also good.

  The heavy equipment sorting circuit investigates the frequency characteristics of the sound generated by each heavy machine by analyzing the frequency of the sound generated by the operation of various construction machines such as bulldozers, tractor excavators, and backhoes. The generated sound can be selectively passed and can be switched to each other. It is desirable that the frequency characteristic unique to each heavy machine is also distinguished from the frequency characteristic of running sound in a general passenger car or train.

  According to such a configuration, it is possible to extract only the measurement value caused by a specific construction machine from the measurement value obtained by the cc microphone 12, and noise monitoring for a specific construction machine can be performed. It becomes possible.

  In the above modification, when the noise level in the heavy equipment-specific site exceeds the target value while filtering for a specific construction machine, the grandchild machine installed in the construction machine It is desirable that the alarm data is received at 31.

  As a specific configuration, for example, information on heavy equipment to be filtered is stored in the hard disk 25 in a form linked to the switching operation of filtering, and noise evaluation is performed when the noise level in the heavy equipment-specific site exceeds a target value. When it is determined by the unit 46, the alarm creation unit 47 is configured to read the heavy machine information stored in the hard disk 25 and include the heavy machine information in the alarm data, and the alarm data is the target construction machine. It is conceivable that the alarm output unit 32 is configured to be output to the portable information terminal.

  Further, in the present embodiment, when the number of arrivals of the generated sound is counted by the arrival frequency counting unit 45 for each arrival angle using the arrival angle data obtained by the arrival angle calculating unit 44, each time the generated sound arrives, However, instead of this, the arrival angle calculation unit is configured so that the magnitude of the energy of the generated sound is calculated as the energy value of the generated sound, and the number of generated sound arrivals May be configured to be weighted with the energy value of the generated sound.

That is, in the arrival angle calculation unit, the following equation is obtained from the sound pressures p ₁ and p ₂ measured by the microphone pair including the microphones 12a and 12b:
E _P = (p ₁ + p ₂ ) ²
Is calculated to calculate the energy E _P of the generated sound.

The energy E _P calculated by the arrival angle calculation unit may be appropriately stored in a storage device such as a hard disk as necessary. Instead of the microphone pair consisting of the microphones 12a and 12b, the energy E _{P of the} generated sound is calculated using the sound pressure measured by the microphone pair consisting of the microphones 12c and 12d or the microphone pair consisting of the microphones 12e and 12f. It doesn't matter if you do.

  Next, as in the above-described embodiment, the arrival frequency counting unit counts the number of arrivals of the generated sound for each arrival angle using the arrival angle data obtained by the arrival angle calculation unit, but simply increments “1”. Instead of accumulating, the number of times weighted by the energy value is accumulated.

That is, if the energy value of the generated sound arriving at the kth (1 ≦ k ≦ M) among the generated sounds arriving at the arrival angle θ is E _P (k), the number _N ′ of generated sounds arriving at the arrival angle. (θ) is expressed by the following equation:
_{N ′} (θ) = Σ (1 · E _P (k)) (k = 1, 2,... M)
Calculate with

  According to such a modification, when the number of arrivals of the generated sound is counted, the number of arrivals is weighted by the magnitude of the generated sound energy, and therefore the influence rate and the noise level by angle are also determined by the magnitude of the generated sound energy. By using the generated sound that is weighted, that is, the influence on the noise becomes more dominant, the influence rate and the noise level for each angle are calculated, thus making it possible to perform a reasonable noise monitoring.

  In addition, the weighting described above makes it possible to appropriately grasp the arrival angles of the generated sounds even when the generated sounds arrive from various angles.

DESCRIPTION OF SYMBOLS 1 Noise monitoring system 2 Site 3 Construction machine 11 Child machine 12 cc microphone (Sound pressure measuring means)
12a to 12f Microphone 13 Sound level meter (noise measurement means)
21 Master unit 31 Grandchild unit 32 Alarm output unit 41 Filter unit 42 Auditory correction circuit 44 Arrival angle calculation unit 45 Arrival frequency counting unit 46 Noise evaluation unit 47 Alarm creation unit

Claims (8)

It is composed of a plurality of microphone pairs formed by arranging microphones having directivity so that the maximum sensitivity directions are opposite to each other, and each microphone pair is arranged along a plurality of axes that are not parallel to each other and sandwich their origins. Sound pressure measuring means respectively disposed in
A noise measuring means arranged in the vicinity of each microphone for measuring the sound pressure of the generated sound as a noise level;
A filter unit provided with an auditory correction circuit that filters the measurement value of each microphone with a frequency weighting characteristic substantially the same as the frequency weighting characteristic built in the noise measuring means;
An arrival angle calculation unit configured to calculate an arrival angle of the generated sound using output data from the filter unit;
An arrival frequency counting unit that counts the number of arrivals of the generated sound in a predetermined time width for each arrival angle using the arrival angle data obtained by the arrival angle calculation unit;
Dividing the number of arrivals for each arrival angle obtained by the arrival frequency counting unit by the sum of all directions to calculate the influence rate for each arrival angle, and using the influence rate and the noise level, A noise monitoring system comprising: a noise evaluation unit that evaluates a noise index caused by the generated sound as a noise level by angle. When the noise level is L and the sum of the influence rates over the predetermined angle range is C _T , the noise level for each angle is L _T ,
L _T = L + 10 · logC _T (1)
The noise monitoring system according to claim 1, wherein the noise evaluation unit is configured to be calculated from: 2. The noise monitoring system according to claim 1, wherein the plurality of microphone pairs are two or three microphone pairs, and the plurality of axes are two or three axes orthogonal to each other. The arrival angle calculation unit is configured such that the magnitude of the energy of the generated sound is calculated as an energy value for each generated sound, and the arrival frequency counting unit is configured so that the number of arrivals of the generated sound is the generated sound. The noise monitoring system according to claim 1, wherein the noise monitoring system is configured so as to be weighted by the energy value. The sound pressure measuring means and the noise measuring means are installed in the vicinity of a boundary of a site where construction work is performed, and the noise level is calculated so that the angle range overlooking the site is the predetermined angle range. The noise monitoring system according to any one of claims 1 to 4, wherein the noise monitoring system is configured as an evaluation unit, and the noise level for each angle is set as a noise level in a site. A heavy machine selection circuit that filters the measurement values of each microphone with a frequency characteristic according to the type of construction machine in the site is provided in the filter unit, and the noise level in the site is set as a noise level in the site for each heavy machine. The noise monitoring system according to claim 5. The noise level in the site or the noise level in the site by heavy machinery is compared with a predetermined target value, and alarm data is output when the noise level in the site or site noise level by heavy machinery exceeds the target value. The noise monitoring system according to claim 5 or 6, further comprising an alarm creating unit to be created and an alarm output unit for outputting the alarm data created by the alarm creating unit. The noise monitoring system according to claim 7, wherein the alarm output unit is provided in a construction machine that operates in the site.

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