KR100366206B1 - Real-time diagnostics and monitoring system and method for transportation machinery by using sound visualization system and method of band-limited noise - Google Patents

Abstract

The present invention relates to a system and method for imaging acoustic characteristics using a hologram of narrowband noise emitted from a moving noise source, and to measuring changes in the noise source by measuring holograms on the side and bottom noise sources of a moving transportation machine. By sensing, the present invention also relates to a system and method for diagnosing and monitoring a transport machine in a non-contact state during operation of the transport machine.

The method for imaging narrowband noise according to the present invention comprises a first step of obtaining a spectrum at the total band ( f _h ) and the center frequency ( f _hc ) of narrowband noise emitted from a noise source at a reference position, and at the measurement position. A second step of measuring a sound pressure ( p _m ) of the noise radiated from the noise source, a third step of obtaining a ratio of the spectrum at the entire frequency band of the narrowband noise to the spectrum at the center frequency, and in the second step And dividing the sound pressure by the spectral ratio obtained in the third step from the sound pressure of the measured noise to obtain a hologram of narrowband noise and imaging it.

In addition, the condition monitoring system of the transport machine according to the present invention, spaced apart from the lower surface and the side surface of the transport machine at any position of the path passing by the transport machine, a certain distance is installed in parallel to each of the transport machine A bottom and side microphone array for measuring sound pressure of narrowband noise emitted from the base; A reference microphone attached to the transport machine for measuring the spectrum at the whole frequency and the spectrum at the center frequency of the narrowband noise emitted from the transport machine; A signal obtained by imaging a ratio of the spectrum in the entire band of the noise and the spectrum at the center frequency and dividing the sound pressure by the ratio of the spectrum from the sound pressure of the noise measured by the bottom and side microphone arrays to obtain a hologram of the noise. Processing means; Storage means for storing a noise map during driving in normal and abnormal states of the transport machine; And retrieving means for monitoring the state of the transportation machine by retrieving the hologram of the noise of the transportation machine from the noise map stored in the storage means.

Description

A system and method for imaging narrowband noise, and a system and method for monitoring the state of a transportation machine using the same {real-time diagnostics and monitoring system and method for transportation machinery by using sound visualization system and method of band-limited noise}

The present invention relates to a method for imaging acoustic characteristics using a hologram of noise emitted from a moving noise source, and more particularly, to a method for imaging narrowband noise having a constant band as well as a single frequency. . In addition, the present invention relates to a system and method for diagnosing and monitoring a transport machine in a non-contact state during operation of the transport machine by detecting a change in the noise source by measuring holograms on the side and lower noise sources of the transport machine. Do.

It is widely used in both civil and military industries to obtain information about sound sources by measuring sound pressure on an arbitrary reference surface and obtaining holograms of sound fields. Such information includes a farfield directivity information in a sound source, a nearfield vector intensity information, a surface velocity information, and a total sound information in a near field. power information).

The technology to search the location and intensity of sound sources using the hologram of the sound field configured as above can be applied for the search of the enemy in the military industry, and in the civil industry, it is applied to search and remove the noise source or install the soundproof wall. Can be. In particular, as awareness of environmental rights and living rights has increased in recent years, the necessity of obtaining accurate information on such noise sources and dealing with them appropriately has increased.

The achievements of this study of holography in acoustics have accumulated quite a lot everywhere, especially among others. D. J. D. Maynard and Lee. G. E. G. Williams and Y. "Acoustic Sound in the Near Field," published in Journal of the Acoustical Society of America, Vol. 74, No. 4, pp 1395-1413, by Y. Lee, Vol. 74, No. 74, Vol. 1. Theory of generalized holography and the development of NAH in "Nearfield Acoustic Holography (NAH)" and Jay. D. J. D. Maynard and Lee. G. The contents of "Nonwavelength-limited holographic sound field reconstruction" in U.S. Patent No. 4,415,996 to Williams (EG Williams) and in 1989, published by BK, Inc. J in Technical Review No 1, 1989, BK publication. J. Hald's "Method of Spatial Transformation of Sound Fields-a unique technique for scan-based near-field acoustic holography without restrictions on" coherence, and Journal of the Acoustical Society of Loyau, J. Pascal, and P. Gaillard, 1988, Vol. 84, No. 84, Vol. A paper entitled "Broadband acoustic holography reconstruction from acoustic intensity measurement", published in of America, Vol. 84, No. 5, pp 1744-1750, is related to this invention.

Here, acoustic holography is a method of predicting the characteristics of sound waves, i.e., behaviour, at any location in all spaces of interest by analyzing the hologram after obtaining a hologram from a reference surface called a hologram surface. . The holographic surface may be defined as a plane, a cylindrical surface, or a spherical surface, and according to the shape of such hologram surface, planar acoustic holography, cylindrical acoustic holography, and spherical acoustic holography Are distinguished.

Since planar acoustic holography is intended to obtain a hologram representing sound pressure distribution on an infinite plane, it is theoretically necessary to measure sound pressure at an infinite number of measuring points. However, practically, a hologram is obtained by selecting a finite number of measurement points in consideration of measurement cost and time constraints, and measuring sound pressure at those measurement points. The accuracy of the hologram thus obtained depends on the density of the measuring points, i.e. the size of the spacing of the measuring points, and as the spacing of the measuring points becomes larger, the accuracy of the hologram is significantly lowered. Naturally, the reliability of the sound field predicted by the inaccurate hologram is lost, and can sometimes cause serious errors. Therefore, efforts and researches are being conducted to enable high-precision holograms without sacrificing errors by allowing to obtain holograms with high accuracy while reducing time and cost.

In the paper presented in the 1985 edition of the American Society for Acoustic Acoustics, sound pressure, particle velocity, acoustic intensity, and acoustic power at all positions in the free field, using sound pressure distributions (holograms) measured by multiple microphones, were presented. We described that we can predict useful physical quantities. However, in order to apply this acoustic holography method to a moving machine, it is inconvenient to measure the hologram while moving the planar microphone array together with the transport machine as a sound source.

The above acoustic holography method is p. P. Rasmussen and S. S. Gade and B. Actually applied by B. Ginn, "Tyre noise measurement on moving vehicles" at the 1996 Proceedings of Fourth international congress on sound and vibration. a moving vehicle ". However, this should limit the size of the measurement diameter, there is a problem such as noise caused by wind, increased cost due to complex measuring equipment.

That is, the fundamental limitation of the conventional method described above is that since the sound pressure is simply measured without considering the relative motion between the microphone and the sound source, accurate measurement can be obtained only when the microphone and the sound source are stopped during the measurement time. In other words, accurate measurement was not possible for the moving sound source. In addition, even when measuring a fixed sound source, so-called scanning method (measuring scanning method for measuring) to measure while moving the microphone was not available, it took a lot of time and equipment for the measurement.

On the other hand, there have been various attempts to visualize mobile sound sources. F. King III and D. "Due to the noise from railroads generated by high-speed trains," published in D. Bechert's 1979 Journal of Sound and Vibration, Vol. 66, pp. 311-332. On the sources of wayside noise generated by high-speed trains, the paper presented a method for using linear microphone arrays or cross-shaped or X-shaped two-dimensional microarrays. This is a type of beam forming method (beam forming method) mainly applied to high-speed trains. However, this method is a method of expressing only the sizes of sound sources assumed in a plane to be visualized, and has a disadvantage in that it is impossible to express propagation of noise emitted from an actual sound source.

On the other hand, H. As an acoustic holography method (MFAH) for a moving frame. s. H. S. Kwon and Y. H. "Moving frame technology for planar acoustic holography," published in Journal of the Acoustical Society of America, Vol. 103, pp 1734-1742, published in 103, 1998 edition of 103. technique for planar acoustic holograph) and Korean Patent No. 217827, "System and method for measuring the hologram of a moving sound source to image acoustic characteristics," refers to a microphone array that moves at a relative speed with respect to a sound source, In addition, a system and method for measuring acoustic hologram using an array of linear microphones fixed to the ground when a sound source is moved and imaging the noise emitted from the sound source have been disclosed.

However, the conventional acoustic holography method (MFAH) for the moving frame was able to visualize only the moving noise source generating only a single frequency. Therefore, there is a problem that imaging of noise having a frequency band is impossible.

SUMMARY OF THE INVENTION An object of the present invention for solving the above problems of the prior art is to provide a narrowband noise imaging system and method for visualizing a moving noise source that generates narrowband noise as well as a single frequency.

In addition, another object of the present invention is to provide a system and method for measuring a hologram of a noise source of a moving transportation machine and real-time non-contact monitoring of the state of the transportation machinery.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view for explaining the present invention and shows a relative coordinate system expressing a relation between a sound pressure distribution of a moving noise source and a sound pressure distribution of a hologram surface measured by a microphone array.

FIG. 2 is a diagram for explaining the present invention, and illustrates a method for calculating a hologram from a sound field which is a plane wave.

3 is a diagram illustrating a process of hologramizing narrowband noise in a frequency domain according to an embodiment of the present invention;

Figure 4 is a block diagram showing a state monitoring system of a transport machine according to an embodiment of the present invention,

FIG. 5 is a view showing experimental results of imaging narrowband noise emitted from a transportation machine using the system of FIG. 4.

※ Explanation of code about main part of drawing ※

1: bottom side microphone array 2: sound absorbing material

3: side microphone array 4: reference microphone

5: optical sensor 6: multi-channel signal collector

7: telemetry 8: digital signal processor

A system for imaging narrowband noise according to the present invention for achieving the above object is spaced a certain distance from the lower and side surfaces of the transport machine at any position of the path through which the transport machine passes, and parallel to each plane. A bottom surface and side microphone array installed so as to measure sound pressure of narrowband noise radiated from the transport machine;

A reference microphone attached to the transport machine for measuring the spectrum at the full band and the center frequency of the narrowband noise emitted from the transport machine;

A signal obtained by imaging a ratio of the spectrum in the entire band of the noise and the spectrum at the center frequency and dividing the sound pressure by the ratio of the spectrum from the sound pressure of the noise measured by the bottom and side microphone arrays to obtain a hologram of the noise. Characterized in that it comprises a processing means.

In addition, the method for imaging narrowband noise according to an embodiment of the present invention, the first method for obtaining the spectrum at the total band ( f _h ) and the center frequency ( f _hc ) of the narrowband noise emitted from the noise source at the reference position Steps,

A second step of measuring a sound pressure p _{m of} noise radiated from the noise source at a measurement position,

A third step of obtaining a ratio of the spectrum in the entire band of the narrowband noise to the spectrum in the center frequency, and

And a fourth step of dividing the sound pressure by the spectral ratio obtained in the third step from the sound pressure of the noise measured in the second step to obtain a hologram of narrowband noise and imaging it.

In addition, the condition monitoring system of the transport machine according to the present invention, spaced apart from the lower surface and the side surface of the transport machine at any position of the path passing by the transport machine, a certain distance is installed in parallel to each of the transport machine A bottom and side microphone array for measuring sound pressure of narrowband noise emitted from

A reference microphone attached to the transport machine for measuring the spectrum at the full frequency and the spectrum at the center frequency of the narrowband noise emitted from the transport machine;

A signal obtained by imaging a ratio of the spectrum in the entire band of the noise and the spectrum at the center frequency and dividing the sound pressure by the ratio of the spectrum from the sound pressure of the noise measured by the bottom and side microphone arrays to obtain a hologram of the noise. Treatment means,

Storage means for storing a noise map during driving in a normal state and an abnormal state of the transport machine;

And a retrieval means for retrieving the hologram of the noise of the transport machine from the noise map stored in the storage means to monitor the state of the transport machine.

In addition, the condition monitoring method of the transport machine according to the present invention, the first step of constructing the database by imaging the hologram of the noise emitted from the transport machine while operating the transport machine for building the database in a normal state and an abnormal state;

A second step of imaging the hologram of the noise emitted by the transportation machine to be monitored during operation;

And a third step of diagnosing a state of the transport machine by searching a noise image of the monitored transport machine in a database.

Hereinafter, with reference to the accompanying drawings will be described in more detail "system and method for imaging narrowband noise, and a system and method for monitoring the state of the transport machine using the same" according to an embodiment of the present invention in more detail. .

First, the theory underlying the narrowband noise imaging method is described.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram for explaining the present invention, and shows a relative coordinate system expressing a relationship between a sound pressure distribution of a moving noise source and a sound pressure distribution of a hologram surface measured by a microphone, and FIG. FIG. 3 is a diagram illustrating a method of calculating holograms from a plane wave sound field, and FIG. 3 is a diagram illustrating a process of hologramizing narrowband noise in a frequency domain according to an embodiment of the present invention. .

In general, in a moving frame acoustic holography (MFAH), a holographic coordinate system (( x _h , y _h , z _h )) , which is fixed to a sound source and expresses the movement of the sound source, and a measurement coordinate system (( x _m , y _m , z ) in which a microphone is fixed _m )) to obtain the hologram which is the sound field information expressed as the Doppler effect on the measured sound pressure through the relative coordinate transformation.

In this case, it is assumed that the relative speed u _{m / h} (t) between the microphone and the sound source is u _m (t) -u _h (t) , and the influence of acceleration is small enough to be negligible. When the sound source is moved and the microphone is stopped, the reference coordinate system (X, Y, Z) is the same as the measurement coordinate system (( x _m , y _m , z _m )), so the sound pressure (p) in the reference coordinate system is It can be expressed as the sound pressure p _m of Equation 1.

Therefore, the sound pressure p _h in the hologram coordinate system is obtained as in Equation 3 through the relative coordinate transformation in Equation 2.

here, to be.

When this is applied to a plane wave sound field as shown in FIG. 2, z _h = z _H in any plane, and the plane wave traveling in the x direction is expressed by Equation 4 below.

here, Is a hologram representing the sound pressure distribution in space. Looking at the equation (4), the sound field of the pure sound is spatial information (hologram) ) And timely information ( Is a product of On the other hand, when the microphone moves at a speed of u _{m / h} (t) = u _m (t) in the x direction, this information is also included in the time signal measured by the microphone, which is expressed as a Doppler effect. In other words, since the Doppler effect is expressed in different forms according to the shape of the sound field, the Doppler effect may inverse the sound field. The time signal measured by the microphone moving from Equation 3 and Equation 4 may be expressed as Equation 5.

That is, the hologram knows the frequency ( f _h0 ) and the relative coordinate transformation equation ( x _h = S _{m / h} (t) ), It can be obtained by multiplying it, which is represented by the complex envelope of the measurement signal.

On the other hand, since any sound field can be expressed as a superposition of plane waves, the result can be extended for any single frequency sound field.

In other words, In the case of a single frequency sound field expressed as, the measured sound pressure is equal to Equation 6 and the hologram is obtained as a complex envelope of the measured signal as in Equation 5.

Based on the theory so far, the theory of imaging narrowband noise is explained. 3 illustrates a method of applying MFAH when the noise source generates band noise. When the noise source generates band noise, if the bandwidth is narrow band noise less than 10% of the center frequency, the hologram of the band noise can be obtained using MFAH. If the center frequency and bandwidth of the narrowband noise is f _hc and B , respectively, the sound field is expressed by Equation (7).

Here, f _{h −} = f _hc − B / 2 , f _{h +} = f _hc + B / 2 , and if the noise is formed by non-independent sources, the sound field may be modeled as in Equation 8. In practice, a filter is used to obtain only this narrowband noise.

Here, A (f _h ) represents a normalized sound source spectrum. Therefore, Equation 7 above may be expressed as Equation 9 below.

The normalized sound source spectrum A (f _h ) can be obtained from Equation 10 below from a reference microphone fixed to the sound source.

here, Indicates the position of the reference microphone, Wow Represent the spectra at the frequency f _h and the center frequency f _hc , respectively. Therefore, the sound field of the narrow band noise from Equations 9 and 10 is expressed as Equation 11 below.

From this equation, it can be seen that the narrowband noise is also expressed in the form of a product of a hologram representing spatial information and a sound source spectrum representing temporal information, and a hologram can be obtained by MFAH. That is, the measurement signal obtained from the microphone array is obtained from Equation 3 and 11 as shown in Equation 12 below.

The hologram P _hc of narrowband noise can be obtained by dividing the complex measurement signal p _m by the reference microphone signal p _ref / P _{ref, c} .

Figure 4 is a block diagram showing a real-time state monitoring system of the transport machine according to an embodiment of the present invention. In the present invention, the image of the narrow-band noise emitted from the transport machine including a lower side microphone array (1) installed along the z-axis parallel to the ground and a reference microphone (4) installed at the bottom of the transport machine to generate a reference sound pressure .

At this time, the sound pressure measured in the measurement coordinate system in which the lower surface microphone array 1 is located has a relationship as shown in Equation 13 with the sound pressure in the reference coordinate system in which the reference microphone 4 is located.

In addition, the sound pressure p _h in the hologram coordinate system in which the noise source is located is obtained as shown in Equation 14 using the relative coordinate transformation of Equation 2.

Comparing Equation 14 above and Equation 3, which is a formula for visualizing a hologram in terms of a transport machine, only y and z coordinate values are changed. That is, applying the equation (14) to the theory of Figures 1 to 3 it is possible to obtain a hologram of the lower noise source of the transport machine.

Referring to Figure 4, the system for monitoring the state of the transport machine according to the present invention, the bottom side microphone array (1) and the bottom side microphone array installed along the z-axis parallel to the ground at any point of the path that the transport machine passes Sound absorbing material (2) installed on the ground on which the array (1) is installed to reduce reflection of noise radiated from the noise source, side microphone array (3) installed parallel to both sides of the transport machine, and installed on the lower part of the transport machine. A reference microphone (4) for measuring sound pressure and two pairs of optical sensors (5) for measuring the relative position with respect to the microphone array (1) (3) of the transport machine by detecting the vehicle entry and exit times And a multichannel signal collector 6, reference microphone 4, which simultaneously measures signals from the reference microphone 4 and the bottom and side microphone arrays 1, 3 and the optical sensor 5; ) And wireless transmission and reception of a synchronization signal for synchronizing signals from the bottom and side microphone arrays (1) (3) and the signal measured by the reference microphone (4) to the multi-channel signal collector (6). Telemetry 7 and a digital signal processor 8 for imaging radiation noise using the measured sound pressure.

Here, the interval between the microphones of the lower and side microphone arrays (1) (3) is set to about 1/4 of the wavelength of the highest frequency of interest, and the optical sensor (5) is larger than the aperture size of the hologram to be visualized. Set large. In general, the digital signal processor 8 is installed in a personal computer and images radiation noise from sound pressure signals measured by reference microphones and microphone arrays based on the narrowband noise imaging theory described above.

Referring to the method of monitoring the state of the transport machine using the system configured as described above are as follows.

First of all, various noises emitted from a transportation machine are imaged through the above-described system while driving various transportation machines at various speeds in a steady state and an abnormal state. The imaged noise overlaps with the image representing the geometric shape of the transportation machine to generate a noise map representing the noise emission of each part of the transportation machine. In other words, the reference point and scale of the noise image diagram are set to be the same as the reference point and accumulation of the geometrical diagrams on the side and bottom of the transport machine, and the overlapping process is performed. In this way, the noise map radiated from the steady state and the abnormal state for each speed for each transport machine is built into the database by speed and frequency and stored in a computer.

After that, by applying the actual transport monitoring machine to the system described above, the noise emitted from the transport machine is imaged in real time, and the noise map retrieved by inputting the speed map and the frequency and noise map overlapping the geometry of the transport machine. In comparison, the condition of the transport machine is diagnosed and monitored.

5 is to measure the hologram of the sound field emitted from the speaker while fixing the center frequency to 450Hz and changing the bandwidth to (a) 10Hz, (b) 32Hz, (c) 100Hz to verify the applicability to the band noise, The prediction result in the sound source plane is shown. At this time, the vehicle moved at a constant speed and used 16 microphone arrays perpendicular to the ground. In other words, all three cases accurately measure the hologram.

While the invention has been described above based on the preferred embodiments thereof, these embodiments are intended to illustrate rather than limit the invention. It will be apparent to those skilled in the art that various changes, modifications, or adjustments to the above embodiments can be made without departing from the spirit of the invention. Therefore, the protection scope of the present invention will be limited only by the appended claims, and should be construed as including all such changes, modifications or adjustments.

As described above, according to the present invention, since the lower noise source of the transport machine exposed to the noise source can be visualized in time and space using not only the microphone array perpendicular to the ground but also the horizontal microphone array, the state of the transport machine can be contacted and Diagnosis can be made in real time. In particular, since the sound pressure distribution of the noise source and the propagation of the acoustic energy are imaged, it is possible to identify the abnormal operation state of the transportation machine even if it is not a related expert, and to database the occurrence and changes of the noise source due to the aging of the vehicle. By using it, it can contribute greatly to the development of the vehicle which is excellent in noise and vibration.

Claims (13)

A lower surface which is spaced a certain distance from the lower surface and the side surface of the transport machine at an arbitrary position of a path through which the transport machine passes, and is installed parallel to each surface to measure the sound pressure of narrowband noise radiated from the transport machine; Side microphone arrays, A reference microphone attached to the transport machine for measuring the spectrum at the full frequency and the spectrum at the center frequency of the narrowband noise emitted from the transport machine; A signal obtained by imaging a ratio of the spectrum in the entire band of the noise and the spectrum at the center frequency and dividing the sound pressure by the ratio of the spectrum from the sound pressure of the noise measured by the bottom and side microphone arrays to obtain a hologram of the noise. Narrowband noise imaging system, characterized in that it comprises a processing means. The method of claim 1, And the spacing between the microphones of the lower surface and side microphone arrays is set to 1/4 of a wavelength corresponding to the highest frequency among the frequencies to be measured. A first step of obtaining a spectrum at the total band ( f _h ) and the center frequency ( f _hc ) of the narrow band noise emitted from the noise source at the reference position, A second step of measuring a sound pressure p _{m of} noise radiated from the noise source at a measurement position, A third step of obtaining a ratio of the spectrum in the entire band of the narrowband noise to the spectrum in the center frequency, and And a fourth step of dividing the sound pressure by the spectral ratio obtained in the third step from the sound pressure of the noise measured in the second step to obtain a hologram of the narrowband noise and image it. A lower surface which is spaced a certain distance from the lower surface and the side surface of the transport machine at an arbitrary position of a path through which the transport machine passes, and is installed parallel to each surface to measure the sound pressure of narrowband noise radiated from the transport machine; Side microphone arrays, A reference microphone attached to the transport machine for measuring the spectrum at the full frequency and the spectrum at the center frequency of the narrowband noise emitted from the transport machine; A signal obtained by imaging a ratio of the spectrum in the entire band of the noise and the spectrum at the center frequency and dividing the sound pressure by the ratio of the spectrum from the sound pressure of the noise measured by the bottom and side microphone arrays to obtain a hologram of the noise. Treatment means, Storage means for storing a noise map during driving in a normal state and an abnormal state of the transport machine; And a retrieving means for retrieving the hologram of the noise of the transport machine from the noise map stored in the storage means to monitor the state of the transport machine. The method of claim 4, wherein The interval between the microphones of the lower surface and the side microphone array is set to 1/4 of the wavelength corresponding to the highest frequency of the frequency to be measured. The method of claim 4, wherein And a sound absorbing material installed on the ground on which the bottom surface microphone array is installed. The method of claim 4, wherein The lower surface of the transport machine and a pair of optical sensors are installed at any position of the path passing by the transport machine for measuring the entry and exit time of the transport machine to provide to the signal processing means, and A condition monitoring system for a transportation machine, characterized by measuring the relative position of the side microphone array. The method of claim 7, wherein The pair of optical sensors is a condition monitoring system of a transport machine, characterized in that larger than the aperture size of the hologram to be visualized. The method of claim 4, wherein The apparatus further includes a synchronization signal for synchronizing the signal measured by the reference microphone and the signal measured by the bottom and side microphone arrays, and telemetry for wirelessly transmitting and receiving the signal measured by the reference microphone to the signal processing means. A condition monitoring system of a transport machine. A first step of constructing a database by imaging holograms of noise emitted from the transport machine by frequency while operating the transport machine for constructing a database in a steady state and an abnormal state while changing a speed; A second step of imaging the hologram of the noise emitted by the transportation machine to be monitored during operation; And a third step of diagnosing a state of the transport machine by searching a noise image of the monitored transport machine in a database. The method of claim 10, The first step is to calculate the ratio of the spectrum at the center frequency ( f _hc ) and the total band ( f _h ) of the narrowband noise emitted from the noise source at the reference position, for the database construction transport machine, The sound pressure ( p _m ) of the noise emitted from the noise source is divided by the sound pressure by the ratio of the spectrum, and the state monitoring method of the transport machine, characterized in that to image the hologram of the noise emitted from the transport machine for building the database . The method of claim 10, The second step is to determine the ratio of the spectrum at the center frequency ( f _hc ) and the total band ( f _h ) of the narrow-band noise emitted from the noise source at the reference position with respect to the transportation machine to be monitored, and measured at the measurement position The sound pressure ( p _m ) of the noise radiated from the noise source is divided by the sound pressure by the ratio of the spectrum, to image the hologram of the noise emitted from the transportation machine to be monitored. The method according to any one of claims 10 to 12, In the first step, a noise map representing noise radiation of each part of the transport machine is generated and databased by overlapping the noise emitted from the transport vehicle for constructing the database with the geometric image of the transport machine for constructing the database. The second step is to query the database with a hologram of the noise emitted by the transportation machine to be monitored during operation and a noise map overlaid on the geometric image of the transportation machine, and the speed and frequency to determine the state of the transportation machine to be monitored. And monitoring the condition of the transport machine.