Three-dimensional sound intensity noise monitoring method based on reverberation correction

Abstract

The invention discloses a three-dimensional sound intensity noise monitoring method based on reverberation correction, and belongs to the field of mechanical equipment state monitoring based on noise. According to the method, the characteristic that an indoor sound field is formed by superposition of direct sound and reverberation sound is utilized, a corresponding filter is designed, the reverberation sound in a sound signal is corrected through filtering, theoretical knowledge of solving sound power of a sound source by combining a three-dimensional sound intensity method is combined, and a sound power value after reverberation correction is obtained; therefore, more accurate state monitoring is carried out on the operation process of the equipment. Compared with other methods, the method provided by the invention can correct the reverberant sound of sound signals in closed or semi-closed environments such as workshops on the basis of not needing real sound source signals, obtain more accurate sound source sound power and realize more accurate noise state monitoring, has engineering application significance, and is suitable for popularization and application. And a new method is provided for noise monitoring and diagnosis of mechanical equipment with higher precision.

Description

Technical Field

[0001] The invention relates to a three-dimensional sound intensity noise monitoring method based on reverberation correction, and belongs to the field of noise-based mechanical equipment state monitoring. Background Art

[0002] Mechanical equipment is often accompanied by a lot of noise during operation, which contains a wealth of information about the operating status of mechanical equipment parts. By analyzing and calculating these noise information, the operating status of mechanical equipment can be reflected and used for status monitoring. However, there is a lot of reverberation in the indoor closed or semi-closed environment where the mechanical equipment is located, which often affects the accuracy of the monitoring results. Therefore, the three-dimensional sound intensity noise monitoring method needs to correct the reverberation in the sound signal to further improve the accuracy of the monitoring results.

[0003] In the field of signal processing, the earliest dereverberation technologies proposed were mainly aimed at voice signals in communications. However, these methods require real sound source signals. For mechanical equipment operating in closed or semi-closed environments such as workshops, it is usually impossible to obtain their real sound source signals. Therefore, the dereverberation technology applied to voice signals in communications is not suitable for noise state monitoring.

[0004] In a complex workshop environment, near-field acoustic holography has the disadvantages of requiring the measurement array to be close to and cover the surface of the sound source, and the difficulty of on-site measurement. The beamforming method has the disadvantages of being unable to calculate the accurate sound source intensity in a complex sound field. The three-dimensional sound intensity test technology developed on the basis of one-dimensional sound intensity test can obtain the three-dimensional sound intensity vector in space by using a special three-dimensional sound intensity probe, and then analyze the characteristics of the sound source. The three-dimensional sound intensity method has the advantages of being less affected by the environment and high measurement accuracy. Therefore, the three-dimensional sound intensity method is more suitable for noise source state monitoring in a complex environment. Gunasegaran V et al. used the sound intensity method to monitor faults on rolling and sliding contact elements. Han Jiyuan et al. applied sound intensity technology to the study of dynamic response and noise prediction of spur gear transmission systems. Compared with one-dimensional sound intensity probes, which require a large number of probes during the measurement process and have a more complicated operation process, the use of three-dimensional sound intensity probes can simplify the operation process. Chai Shiyi et al. further separated multiple sound source spectra based on Lu Yi's sound source identification method, providing ideas for sound source state monitoring based on sound power. Du Wei et al. used the cross-spectrum three-dimensional sound intensity diagnosis method to monitor the faults of high-speed rotating devices. However, these methods do not take into account the interference of reverberation sound on monitoring accuracy.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The present invention provides a three-dimensional sound intensity noise monitoring method based on reverberation correction. In the case of reverberation sound interference, the interference of reverberation sound on noise monitoring can be corrected, thereby improving the accuracy of noise monitoring results.

[0007] The technical solution of the present invention is:

[0008] A three-dimensional sound intensity noise monitoring method based on reverberation correction, comprising:

[0009] Step 1: Determine the reverberation sound correction formula based on the indoor sound field principle;

[0010] Step 2: Calculate the average indoor sound absorption coefficient based on the reverberation time;

[0011] Step 3: Design a 1 / 3 octave filter based on the average indoor sound absorption coefficient and reverberation sound correction formula;

[0012] Step 4: Place a 3D sound intensity probe in a closed or semi-closed 3D space, and select any point in the 3D space as the origin of the 3D rectangular coordinate system, and determine the 3D rectangular coordinates of the sound source and the 3D sound intensity probe based on the determined coordinate origin;

[0013] Step 5: Use a three-dimensional sound intensity probe to collect the sound pressure signal of the sound source. The sound intensity probe is equipped with four microphones. The sound pressures measured by the four microphones on the three-dimensional sound intensity probe are p1, p2, p3, and p4 respectively; wherein p1 is the time domain sound pressure signal collected by microphone 1 on the three-dimensional sound intensity probe, p2 is the time domain sound pressure signal collected by microphone 2 on the three-dimensional sound intensity probe, p3 is the time domain sound pressure signal collected by microphone 3 on the three-dimensional sound intensity probe, and p4 is the time domain sound pressure signal collected by microphone 4 on the three-dimensional sound intensity probe;

[0014] Step 6: Use the 1 / 3 octave filter designed in step 3 to filter the time domain sound pressure signal collected by the three-dimensional sound intensity probe in step 5 to correct the reverberation sound therein;

[0015] Step 7: According to the principle of the cross-power spectrum density sound intensity method and the principle of the three-dimensional sound intensity method derived from the geometric characteristics of the three-dimensional sound intensity probe, the filtered sound pressure signal is analyzed and calculated to obtain the total sound intensity at the center point O of the three-dimensional sound intensity probe. And construct the equation of total sound intensity and sound power; then decompose the total sound intensity into the three directions of X, Y, and Z in three-dimensional space according to the vector characteristics of sound intensity to obtain the sound intensity components, and expand the corresponding expressions to obtain the equation group of sound intensity components and sound power; substitute the position of the sound source in the rectangular coordinate system, the position of the three-dimensional sound intensity probe in the rectangular coordinate system, and the sound intensity components into the equation group of sound intensity components and sound power to solve the sound power value of the sound source; use the sound power after correcting the reverberation to monitor the state of the sound source.

[0016] The reverberation correction formula is expressed as:

[0017]

[0018] In the formula, p 修 is the sound pressure of the sound source after removing the reverberation sound, p is the effective value of the measured sound pressure, S is the total internal surface area of ​​the room, is the average sound absorption coefficient in the room, r is the distance from the receiving point to the sound source, and Q is the directivity factor of the sound source.

[0019] The step 3 is specifically as follows: according to the indoor average sound absorption coefficient and the reverberation sound correction formula, Design a 1 / 3 octave filter for the weighted coefficients; where S is the total interior surface area of ​​the room, is the average sound absorption coefficient in the room, r is the distance from the receiving point to the sound source, and Q is the directivity factor of the sound source.

[0020] The beneficial effect of the present invention is as follows: the present invention utilizes the characteristic that the indoor sound field is composed of the superposition of direct sound and reverberation sound, designs a corresponding filter to correct the reverberation sound in the sound signal through filtering, and then combines the theoretical knowledge of the three-dimensional sound intensity method to solve the sound power of the sound source, and obtains the sound power value after the reverberation is corrected, so as to perform more accurate status monitoring of the equipment operation process. Compared with other methods, the method of the present invention can correct the reverberation sound of the sound signal in a closed or semi-closed environment such as a workshop without the need for a real sound source signal, obtain more accurate sound source sound power, and realize more accurate noise status monitoring, which has engineering application significance and provides a new method for more accurate noise monitoring and diagnosis of mechanical equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a flow chart of the method of the present invention;

[0022] Figure 2 is a schematic diagram of a three-dimensional sound intensity probe used in the present invention;

[0023] Figure 3 It is the 1 / 3 octave spectrum of the sound power level of the sound source obtained by actual measurement in a semi-anechoic chamber before and after the reverberation correction is performed on the white noise signal of the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. It should be noted that the embodiments in this application and the features in the embodiments can be combined with each other arbitrarily without conflict.

[0025] Example 1: Figure 1-3 As shown, a three-dimensional sound intensity noise monitoring method based on reverberation correction includes:

[0026] Step 1: Determine the reverberation sound correction formula based on the indoor sound field principle;

[0027] Step 2: Calculate the average indoor sound absorption coefficient based on the reverberation time;

[0028] Step 3: Design a 1 / 3 octave filter based on the average indoor sound absorption coefficient and reverberation sound correction formula;

[0029] Step 4: Place a 3D sound intensity probe in a closed or semi-closed 3D space, and select any point in the 3D space as the origin of the 3D rectangular coordinate system, and determine the 3D rectangular coordinates of the sound source and the 3D sound intensity probe based on the determined coordinate origin;

[0030] Step 5: Use a three-dimensional sound intensity probe to collect the sound pressure signal of the sound source. The sound intensity probe is equipped with four microphones. The sound pressures measured by the four microphones on the three-dimensional sound intensity probe are p1, p2, p3, and p4 respectively; wherein p1 is the time domain sound pressure signal collected by microphone 1 on the three-dimensional sound intensity probe, p2 is the time domain sound pressure signal collected by microphone 2 on the three-dimensional sound intensity probe, p3 is the time domain sound pressure signal collected by microphone 3 on the three-dimensional sound intensity probe, and p4 is the time domain sound pressure signal collected by microphone 4 on the three-dimensional sound intensity probe;

[0031] Step 6: Use the 1 / 3 octave filter designed in step 3 to filter the time domain sound pressure signal collected by the three-dimensional sound intensity probe in step 5 to correct the reverberation sound therein;

[0032] Step 7: According to the principle of the cross-power spectrum density sound intensity method and the principle of the three-dimensional sound intensity method derived from the geometric characteristics of the three-dimensional sound intensity probe, the filtered sound pressure signal is analyzed and calculated to obtain the total sound intensity at the center point O of the three-dimensional sound intensity probe. And construct the equation of total sound intensity and sound power; then decompose the total sound intensity into the three directions of X, Y, and Z in three-dimensional space according to the vector characteristics of sound intensity to obtain the sound intensity components, and expand the corresponding expressions to obtain the equation group of sound intensity components and sound power; substitute the position of the sound source in the rectangular coordinate system, the position of the three-dimensional sound intensity probe in the rectangular coordinate system, and the sound intensity components into the equation group of sound intensity components and sound power to solve the sound power value of the sound source; use the sound power after correcting the reverberation to monitor the state of the sound source.

[0033] By applying the above technical solution, it can be known that the above solution corrects the reverberation sound in the sound pressure signal and uses the sound pressure signal after the reverberation sound is corrected to calculate the sound power of the sound source; and uses the sound power after the reverberation is corrected to monitor the state of the sound source to improve the accuracy of the monitoring result.

[0034] Furthermore, the reverberation correction formula is expressed as:

[0035]

[0036] In the formula, p 修 is the sound pressure of the sound source after removing the reverberation sound, p is the effective value of the measured sound pressure, S is the total internal surface area of ​​the room, is the average sound absorption coefficient in the room, r is the distance from the receiving point to the sound source, and Q is the directivity factor of the sound source.

[0037] Further, the step 3 is specifically: according to the indoor average sound absorption coefficient and reverberation sound correction formula, Design a 1 / 3 octave filter for the weighted coefficients; where S is the total interior surface area of ​​the room, is the average sound absorption coefficient in the room, r is the distance from the receiving point to the sound source, and Q is the directivity factor of the sound source.

[0038] In view of the problem that a large amount of reverberation sound will be generated when mechanical equipment is running in a closed or semi-closed environment, which will affect the accuracy of noise status monitoring of the equipment in the presence of reverberation, the present invention proposes a three-dimensional sound intensity noise monitoring method based on reverberation correction to achieve the purpose of improving the accuracy of noise status monitoring of mechanical equipment.

[0039] The following uses a white noise played by a loudspeaker placed indoors as an experimental object, and uses a three-dimensional sound intensity probe to collect the white noise played by the loudspeaker as a sound source signal. The process and effect of the present invention are described in detail using the reverberation correction of the sound source as an example:

[0040] 1. According to the indoor sound field principle, the indoor sound field is composed of direct sound and reverberation sound. The total sound energy density of the indoor steady-state sound field is Where W is the sound power of the sound source, is the average sound absorption coefficient in the room, r is the distance from the receiving point to the sound source, c is the speed of sound propagation in the air, and S is the total internal surface area of ​​the room. The total sound pressure level of the indoor steady-state sound field is Among them, L w is the sound power level of the sound source, and Q is the directivity factor of the sound source. Assuming that there is only direct sound in the sound field, the sound pressure level of the direct sound is The difference between the total sound pressure level and the direct sound pressure level is the reverberation sound pressure level, that is, Then the sound pressure level after removing the reverberation is Lp修 =L p测 -ΔL p , combined with the sound pressure level calculation formula and Among them, p 修 is the effective value of the sound pressure after correcting the reverberation sound, p is the effective value of the measured sound pressure, and p 0 =2×10 -5 is the reference sound pressure. The sound pressure of the sound source after removing the reverberation sound is According to this formula, the reverberation correction of the sound pressure signal can be performed.

[0041] 2. According to the national standard for reverberation time measurement, collect the sound pressure signal in a closed or semi-closed environment. Select multiple measuring points and collect the sound pressure signal at each measuring point multiple times. Finally, use the average value of multiple measurements as the final signal of each measuring point, and perform correlation analysis and calculation on the signal to obtain the reverberation time in the environment. Then, according to the formula Calculate the average indoor sound absorption coefficient corresponding to the reverberation time; where V is the volume of the room, S is the total internal surface area of ​​the room, and T 60 is the reverberation time.

[0042] 3. Correction formula based on the average indoor sound absorption coefficient and reverberation sound by A 1 / 3 octave filter is designed for the weighting coefficient. Since the final result of the reverberation time is expressed in 1 / 3 octave according to the measurement standard of the reverberation time, the designed filter is also a 1 / 3 octave filter.

[0043] 4. Select a point in the selected room as the origin of the three-dimensional rectangular coordinate system, and determine the positions of the loudspeaker and the three-dimensional sound intensity probe in the three-dimensional rectangular coordinate system based on this point. In order to facilitate the experiment, the three-dimensional sound intensity probe is set as the coordinate origin, so the three-dimensional rectangular coordinates of the three-dimensional sound intensity probe are: The three-dimensional rectangular coordinates of the loudspeaker are:

[0044] 5. Use a three-dimensional sound intensity probe to collect the sound pressure signal when the speaker plays white noise. The sound intensity probe is equipped with four microphones. The sound pressures measured by the four microphones on the three-dimensional sound intensity probe are p1, p2, p3, and p4 respectively; among which p1 is the time domain sound pressure signal collected by microphone 1 on the three-dimensional sound intensity probe, p2 is the time domain sound pressure signal collected by microphone 2 on the three-dimensional sound intensity probe, p3 is the time domain sound pressure signal collected by microphone 3 on the three-dimensional sound intensity probe, and p4 is the time domain sound pressure signal collected by microphone 4 on the three-dimensional sound intensity probe; the four microphones installed on the three-dimensional sound intensity probe form a regular tetrahedron.

[0045] 6. Use the designed 1 / 3 octave filter to filter the time domain sound pressure signal collected by the three-dimensional sound intensity probe, and analyze and calculate the filtered sound pressure signal.

[0046] 7. According to the principle of the cross-power spectrum density sound intensity method and the principle of the three-dimensional sound intensity method derived from the geometric characteristics of the three-dimensional sound intensity probe, the filtered sound pressure signal is analyzed and calculated to obtain the total sound intensity at the center point O of the three-dimensional sound intensity probe. And construct the equation of sound intensity and sound power; then according to the vector characteristics of sound intensity, decompose the total sound intensity into three directions of X, Y, and Z in three-dimensional space to obtain the sound intensity components and By expanding the corresponding expressions, we can get the equation group of sound intensity components and sound power; finally, substitute the position of the sound source in the rectangular coordinate system, the position of the three-dimensional sound intensity probe in the rectangular coordinate system and the sound intensity components into the equation group of sound intensity components and sound power to solve the sound power value of the sound source.

[0047] The specific steps are as follows:

[0048] Step 7.1: Calculate the total sound intensity at the center O of the sound intensity probe And construct the equation of sound intensity and sound power:

[0049] 1) According to the principle formula of the dual-microphone cross-power spectrum density sound intensity method The sound intensity components in the directions of the edges of the regular tetrahedron model are calculated. The expressions of the sound intensity components in the directions of the edges of the regular tetrahedron model are as follows:

[0050]

[0051] in, is the sound intensity component on each edge of the regular tetrahedron.

[0052] 2) By analyzing and comparing all the solutions, the group with the best approximation effect is selected to represent the sound intensity components in the X, Y, and Z directions of the three-dimensional space at the center O of the three-dimensional sound intensity probe:

[0053]

[0054]

[0055]

[0056] 3) Based on the sound intensity components at the center O of the three-dimensional sound intensity probe in the X, Y, and Z directions of the three-dimensional space, the total sound intensity formula at the center O of the three-dimensional sound intensity probe is obtained by using the vector summation method:

[0057] 4) Construct the equation of total sound intensity and sound power: Among them, ∠ is the vector phase angle.

[0058] Step 7.2: Decompose the total sound intensity into three directions of X, Y, and Z in three-dimensional space according to the vector characteristics of the sound intensity to obtain the sound intensity components and Expand the corresponding expressions to obtain the equations of sound intensity components and sound power:

[0059] 1) Decompose the sound intensity value at the center point O of the three-dimensional sound intensity probe To the X, Y, and Z directions in three-dimensional space, we get and Three sound intensity components.

[0060] 2) Expand and The expressions of the three sound intensity components give the equations for the sound intensity vector and the sound power:

[0061]

[0062]

[0063]

[0064]

[0065] Wherein, R is the distance from the sound source to the three-dimensional sound intensity probe; α is the angle between the directed line segment connecting the sound intensity probe and the sound source point and the positive direction of the Z axis in the rectangular coordinate system; θ is the angle between the projection of the directed line segment connecting the sound intensity probe and the sound source point on the XOY plane and the positive direction of the Y axis.

[0066] Step 7.3: Substitute the position of the sound source in the rectangular coordinate system, the position of the three-dimensional sound intensity probe in the rectangular coordinate system, and the sound intensity component into the equations of sound intensity component and sound power, and solve the sound power value of the sound source:

[0067] 1) The rectangular coordinates of the sound source Cartesian coordinates of 3D sound intensity probe Harmony intensity and Substitute into the equations in step 7.2 (2).

[0068] 2) Use the particle swarm optimization algorithm to solve the equations and obtain the sound power value of the sound source.

[0069] 8. Through the above steps, the reverberation sound in the sound signal generated when the speaker plays white noise is corrected. The 1 / 3 octave frequency spectrum of the sound power level of the sound source before and after the reverberation sound is corrected is expressed in a plane rectangular coordinate system with frequency as the horizontal axis, and the 1 / 3 octave frequency spectrum of the sound power level of the sound source before and after the reverberation correction is obtained.

[0070] Figure 3 The 1 / 3 octave spectrum of the white noise sound power level obtained without the three-dimensional sound intensity noise monitoring method based on reverberation correction is compared with the 1 / 3 octave spectrum of the white noise sound power level obtained with the three-dimensional sound intensity noise monitoring method based on reverberation correction, relative to the 1 / 3 octave spectrum of the white noise sound power level actually measured in the semi-anechoic chamber. It can be seen that the 1 / 3 octave spectrum of the sound power level after reverberation correction is very close to the 1 / 3 octave spectrum of the sound power level actually measured in the semi-anechoic chamber, and the reverberation correction effect is very good.

[0071] The specific implementation modes of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above implementation modes, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A three-dimensional sound intensity noise monitoring method based on reverberation correction, characterized in that: include: Step 1: Determine the reverberation sound correction formula based on the indoor sound field principle; Step 2: Calculate the average indoor sound absorption coefficient based on the reverberation time; Step 3: Design a 1 / 3 octave filter based on the average indoor sound absorption coefficient and reverberation sound correction formula; Step 4: Place a 3D sound intensity probe in a closed or semi-closed 3D space, and select any point in the 3D space as the origin of the 3D rectangular coordinate system, and determine the 3D rectangular coordinates of the sound source and the 3D sound intensity probe based on the determined coordinate origin; Step 5: Use a three-dimensional sound intensity probe to collect the sound pressure signal of the sound source. The sound intensity probe is equipped with four microphones. The sound pressures measured by the four microphones on the three-dimensional sound intensity probe are p1, p2, p3, and p4 respectively; wherein p1 is the time domain sound pressure signal collected by microphone 1 on the three-dimensional sound intensity probe, p2 is the time domain sound pressure signal collected by microphone 2 on the three-dimensional sound intensity probe, p3 is the time domain sound pressure signal collected by microphone 3 on the three-dimensional sound intensity probe, and p4 is the time domain sound pressure signal collected by microphone 4 on the three-dimensional sound intensity probe; Step 6: Use the 1 / 3 octave filter designed in step 3 to filter the time domain sound pressure signal collected by the three-dimensional sound intensity probe in step 5 to correct the reverberation sound therein; Step 7: According to the principle of the cross-power spectrum density sound intensity method and the principle of the three-dimensional sound intensity method derived from the geometric characteristics of the three-dimensional sound intensity probe, the filtered sound pressure signal is analyzed and calculated to obtain the total sound intensity at the center point O of the three-dimensional sound intensity probe. And construct the equation for total sound intensity and sound power; Then, according to the vector characteristics of sound intensity, the total sound intensity is decomposed into the three directions of X, Y, and Z in three-dimensional space to obtain the sound intensity components. The corresponding expressions are expanded to obtain the equation group of sound intensity components and sound power; the position of the sound source in the rectangular coordinate system, the position of the three-dimensional sound intensity probe in the rectangular coordinate system, and the sound intensity components are substituted into the equation group of sound intensity components and sound power to solve the sound power value of the sound source; the sound power after correcting the reverberation is used to monitor the state of the sound source.

2. The three-dimensional sound intensity noise monitoring method based on reverberation correction according to claim 1 is characterized in that: The reverberation correction formula is expressed as: In the formula, p 修 is the sound pressure of the sound source after removing the reverberation sound, p is the effective value of the measured sound pressure, S is the total internal surface area of ​​the room, is the average sound absorption coefficient in the room, r is the distance from the receiving point to the sound source, and Q is the directivity factor of the sound source.

3. The three-dimensional sound intensity noise monitoring method based on reverberation correction according to claim 1 is characterized in that: The step 3 is specifically as follows: according to the indoor average sound absorption coefficient and the reverberation sound correction formula, Design a 1 / 3 octave filter for the weighted coefficients; where S is the total interior surface area of ​​the room, is the average sound absorption coefficient in the room, r is the distance from the receiving point to the sound source, and Q is the directivity factor of the sound source.

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