CN115683323B - Acoustic power measurement system and method of acoustic equipment - Google Patents
Acoustic power measurement system and method of acoustic equipment Download PDFInfo
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Abstract
The invention relates to a sound power measuring system and a sound power measuring method of sound equipment, wherein the method comprises the following steps: s1, shooting sound equipment with a corresponding visual angle; s2, scaling the shot sound generating equipment, and calculating area data of the sound generating equipment at the current visual angle in an image display picture; s3, the fixed point unit sends the fixed point position to the infrared sensing module; s4, the infrared sensing module emits a plurality of infrared rays to the sounding device according to the fixed point position; s5, detecting a plurality of sound intensity data corresponding to the plurality of point positions by the sound intensity measuring module; s6, repeating the steps S1-S5 aiming at the rest view angles of the sounding device; and S7, calculating the total sound power of the sound generating equipment by the sound power calculating module according to the calculation. The invention can realize automatic fixed point by adding the camera shooting unit, the image display unit, the fixed point unit and the infrared sensing module, and automatically calculate and obtain the total sound power of the sound generating device according to a plurality of sound intensity data corresponding to each view angle, area data of each view angle and scaling factors corresponding to each view angle.
Description
Technical Field
The invention belongs to the technical field of acoustic power measurement, and particularly relates to an acoustic power measurement system and an acoustic power measurement method of sound equipment.
Background
From the acoustic power test method, it is known that if the acoustic power of noise is precisely measured by the acoustic pressure method, a special acoustic laboratory is required. In theory, in any case, any shape (or power source) of radiated (or dissipated) acoustic power may employ techniques that accurately determine the sound intensity. As long as the closed surface is surrounded by a sound source (or power source), the measurement is independent of the choice of surface shape and size, and also independent of whether there are other sources of noise on the external surface. The application of sound intensity technology has two advantages, namely firstly, acoustic facilities such as a sound elimination chamber or a reverberation chamber are not needed to be used; and secondly, when the radiation of multiple sound sources is overlapped, the sound field can distinguish different acoustic radiation powers. Under this condition, the sound intensity technique can be used to measure the radiated power of various actual noise sources.
There are two methods for measuring the radiation electric power of a sound source by applying the sound intensity technique: discrete fixed point measurements and scanning measurements. The discrete fixed point measurement method comprises the steps of discretizing a selected measurement surface, averaging the sound intensity value of each surface through measurement of the discrete part in sound intensity measurement of each part, multiplying the sound intensity value by the corresponding surface area, calculating sound power emitted from each surface, finally summing to obtain total sound power, and making a grid by using ropes and wires in actual measurement so as to accurately position a sound intensity probe on a corresponding measuring point. However, the method needs a specific mode to select the measurement points before the test, then the point-by-point test is performed in the measurement process, the time is long, the process is complicated, and the fixed point position is difficult to achieve very precision in the actual measurement.
Disclosure of Invention
In order to solve the above problems in the prior art, the present invention provides a sound power measurement system of a sound generating device, which is capable of realizing automatic pointing by adding a camera unit, an image display unit, a pointing unit and an infrared sensing module, and automatically calculating to obtain the total sound power of the sound generating device according to a plurality of sound intensity data corresponding to the sound generating device at each view angle, area data of the sound generating device at each view angle in an image display screen, and scaling factors corresponding to the sound generating device at each view angle.
The invention adopts the following technical scheme:
the sound power measuring system of the sound production equipment comprises an infrared sensing module, a sound intensity measuring module, a shooting fixed point module and a sound power calculating module, wherein the shooting fixed point module comprises a shooting unit, an image display unit and a fixed point unit;
the shooting unit is used for shooting the sounding devices at all visual angles;
the image display unit is used for displaying the sound generating equipment obtained by shooting, scaling the sound generating equipment obtained by shooting so as to enable the sound generating equipment to be displayed in a proper range of an image display picture, and calculating area data of the sound generating equipment of each view angle in the image display picture after scaling;
the fixed point unit is used for equally dividing the image display picture into corresponding number of surface elements, respectively carrying out fixed points at corresponding positions in the surface elements, and sending the fixed point positions to the infrared sensing module;
the infrared sensing module is used for emitting a plurality of infrared rays towards the sounding device according to the fixed point position by taking the shooting surface of the shooting unit as an emitting surface;
the sound intensity measuring module is used for detecting and obtaining a plurality of sound intensity data corresponding to a plurality of point positions at the same tangent plane position of a plurality of infrared rays;
and the sound power calculation module is used for calculating and obtaining the total sound power of the sound generating device according to the plurality of sound intensity data corresponding to the sound generating device at each view angle, the area data of the sound generating device at each view angle in the image display picture and the scaling factors corresponding to the sound generating device at each view angle.
The invention also provides a sound power measuring method of the sound equipment, which is realized based on the sound power measuring system of the sound equipment, and the method comprises the following steps:
s1, shooting sound equipment with corresponding visual angles by using a shooting unit, and displaying the sound equipment in an image display unit;
s2, the image display unit performs scaling processing on the shot sound generating equipment so that the sound generating equipment at the current visual angle is displayed in a proper range of an image display picture, and the image display unit is also used for calculating area data of the sound generating equipment at the current visual angle in the image display picture after scaling processing;
s3, the fixed point unit equally divides the image display picture into corresponding number of surface elements, respectively carries out fixed points at corresponding positions in the surface elements, and sends the fixed point positions to the infrared sensing module;
s4, the infrared sensing module takes a shooting surface of the shooting unit as an emitting surface, and emits a plurality of infrared rays towards the sounding equipment according to the fixed point position;
s5, detecting the same section position of the plurality of infrared rays by the sound intensity measuring module to obtain a plurality of sound intensity data corresponding to a plurality of point positions;
s6, repeating the steps S1-S5 aiming at the rest view angles of the sounding equipment;
and S7, calculating the total sound power of the sound generating device by the sound power calculating module according to the plurality of sound intensity data corresponding to the sound generating device at each view angle, the area data of the sound generating device at each view angle in the image display picture and the scaling factors corresponding to the sound generating device at each view angle.
As a preferable scheme, in step S3, the pointing unit equally divides the image display screen into a corresponding number of bins, and the selection of the number of bins includes the following steps:
a. dividing an image display picture into a preset initial number of surface elements, respectively carrying out fixed points at the central positions of the surface elements, and sending the fixed point positions to an infrared sensing module;
b. step S4-step S5 are executed based on the fixed point positions of the step a, so that a plurality of sound intensity data corresponding to a plurality of point positions corresponding to the number of the current face elements are obtained;
c. calculating to obtain a sound field non-uniform indication value based on a plurality of sound intensity data corresponding to the number of the current face elements
And judging whether the following formula is established:
wherein ,
the number of the surface elements is represented,
representing a constant factor;
d. if not, increasing the number of the current equally divided surface elements by one, re-executing the steps a-c, and if so, taking the number of the current equally divided surface elements as the final surface element number.
As a preferred embodiment of the present invention,
, wherein ,
represent the first
Sound intensity data corresponding to the individual surface elements,
total sound intensity data representing the measurement surface.
As a preferable solution, in step S3, after dividing the image display screen into a corresponding number of bins, the selecting the fixed point positions of each bin includes the following steps:
A. preprocessing an original image of an image display picture to obtain an interference gray scale image;
B. binarizing the interference gray level image by adopting a threshold segmentation method to obtain a binarized interference image, wherein the binarized interference image comprises a plurality of vertical interference fringes;
C. carrying out refinement treatment on a plurality of interference fringes in the binarized interference image to obtain a plurality of vertical refined interference lines;
D. setting a plurality of sampling lines penetrating through the whole binarization interference image at certain intervals in the direction perpendicular to the thinning interference line so as to obtain a spatial coherence interferogram, wherein the spatial coherence interferogram comprises a plurality of sampling points, and the sampling points are the intersection points of the sampling lines and the thinning interference line;
E. uniformly dividing the space coherence interferogram into space coherence sub-interferograms with the quantity consistent with the number of the finally determined surface elements;
F. and taking the sampling point position of which the sampling value is closest to a preset threshold value in the spatial coherence sub-interferogram as the fixed point position corresponding to the spatial coherence sub-interferogram, namely the fixed point position of the corresponding bin of the spatial coherence sub-interferogram.
Preferably, in the step B, the relation between the binarized interference image and the interference gray scale map satisfies:
wherein ,
representing a binary interference image
The gray value at the location is a function of the gray value at the location,
representing the interference gray-scale pattern
The gray value at the location is a function of the gray value at the location,
representing a binarization threshold.
Preferably, in the step C, the refining process is performed on the multiple interference fringes in the binarized interference image, and the method includes the steps of:
selecting any pixel point to be thinned in the binarized interference image, taking the pixel point to be thinned as a center, and selecting 8 adjacent pixel points surrounding the pixel point to be thinned;
c2, judging whether the pixel points to be thinned are deleted or not based on the pixel values of the 9 pixel points;
and C3, repeating the steps C1-C2 until all pixel points in the binarized interference image cannot be deleted, so as to obtain a plurality of vertical refined interference lines.
Preferably, the method further comprises the steps of: and performing skeleton restoration treatment on the interference fringes after the refinement treatment.
As a preferred scheme, the skeleton repair process is performed on the interference fringes after the refinement process, including the steps of:
identifying end points and branch points of the refined interference line, and presetting a branch importance weight;
starting from each branch point, tracking the pixel point weight of each branch and accumulating to obtain a branch accumulation weight of each branch;
branches with the branch cumulative weight smaller than the branch importance weight are removed.
In step S7, the calculation formula of the total sound power of the sound generating device is as follows:
wherein ,
representing the total sound power of the sound emitting device,
the first of the sound intensity data representing all of the viewing angle measured sound emitting devices
The data of the sound intensity of the sound,
the number of sound intensity data of the sound generating devices measured by all view angles is represented,
indicating the corresponding magnification of the main viewing angle,
indicating the corresponding scaling factor of the side view angle,
indicating the scaling factor corresponding to the top view angle,
area data representing the main viewing angle sound emitting device in the image display screen,
area data representing the side view angle sound emitting device in the image display screen,
area data representing the top-view angle sound emitting device in the image display screen,
and the sum of area data of the three visual angle sounding devices in the image display screen is represented.
The beneficial effects of the invention are as follows:
by additionally arranging the camera shooting unit, the image display unit, the fixed point unit and the infrared sensing module, automatic fixed point can be realized, and the total sound power of the sound generating device is automatically calculated according to a plurality of sound intensity data corresponding to the sound generating device at each view angle, the area data of the sound generating device at each view angle in the image display picture and the scaling factors corresponding to the sound generating device at each view angle.
The scheme for determining the number of the surface elements and the specific fixed point position is provided, and the accuracy of the calculation of the total sound power of the sound generating device can be ensured on the basis of the minimum point positions.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of an acoustic power measurement system of an acoustic device according to the present invention;
FIG. 2 is a flow chart of a method of measuring acoustic power of an acoustic device according to the present invention;
FIG. 3 is a schematic view of a measurement face arrangement;
FIG. 4 is a schematic diagram of a binarized interference image;
FIG. 5 is a schematic diagram of a refined interference line;
FIG. 6 is a schematic diagram of the domain during pixel deletion;
FIG. 7 is a schematic diagram of the results of a skeleton repair process;
fig. 8 is a spatial coherence interferogram.
Detailed Description
The following specific examples are presented to illustrate the present invention, and those skilled in the art will readily appreciate the additional advantages and capabilities of the present invention as disclosed herein. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention. It should be noted that the following embodiments and features in the embodiments may be combined with each other without conflict.
Embodiment one:
referring to fig. 1, the embodiment provides an acoustic power measurement system of a sound generating device, which includes an infrared sensing module, a sound intensity measurement module, a shooting fixed point module, and an acoustic power calculation module, where the shooting fixed point module includes a shooting unit, an image display unit, and a fixed point unit;
the shooting unit is used for shooting the sounding equipment at each view angle, wherein each view angle of the sounding equipment comprises a main view angle, a side view angle and a overlook angle;
the image display unit is used for displaying the photographed sound generating device, scaling the photographed sound generating device so that the sound generating device can be displayed in a proper range of an image display picture (the proper range is to be interpreted as that the sound generating device occupies the whole image display picture as far as possible), and calculating to obtain area data (namely, the area occupied by the image display picture) of the sound generating device with each view angle in the image display picture after scaling;
the fixed point unit is used for equally dividing the image display picture into corresponding number of surface elements, respectively carrying out fixed points at corresponding positions in the surface elements, and sending the fixed point positions to the infrared sensing module;
the infrared sensing module is used for emitting a plurality of infrared rays towards the sounding device according to the fixed point position by taking the shooting surface of the shooting unit as an emitting surface;
the sound intensity measuring module is used for detecting and obtaining a plurality of sound intensity data corresponding to a plurality of point positions at the same tangent plane position of a plurality of infrared rays, the tangent plane is about 1m away from the sounding equipment, and the error of the sound intensity data measured at the moment is smaller;
and the sound power calculation module is used for calculating and obtaining the total sound power of the sound generating device according to the plurality of sound intensity data corresponding to the sound generating device at each view angle, the area data of the sound generating device at each view angle in the image display picture and the scaling factors corresponding to the sound generating device at each view angle.
Therefore, the invention can realize automatic fixed point by additionally arranging the camera shooting unit, the image display unit, the fixed point unit and the infrared sensing module, and automatically calculate and obtain the total sound power of the sound generating device according to a plurality of sound intensity data corresponding to the sound generating device at each view angle, the area data of the sound generating device at each view angle in the image display picture and the scaling factor corresponding to the sound generating device at each view angle.
The sounding device is a smoke exhaust ventilator, a refrigerator, an automobile engine, an air compressor and the like.
Embodiment two:
the embodiment provides a sound power measuring method of a sound generating device, which is implemented based on the sound power measuring system of the sound generating device according to the first embodiment, and the measuring principle of the measuring system is explained by explaining the measuring method.
Referring to fig. 2, the measurement method includes the steps of:
s1, shooting sound equipment with corresponding visual angles by using a shooting unit, and displaying the sound equipment in an image display unit;
referring to fig. 3, the imaging unit captures an image of the sound emitting device at the corresponding angle of view to determine the measurement plane, i.e., the xAy plane, the measurement plane of the main view angle, i.e., the xAz plane, the measurement plane of the side view angle, i.e., the yAz plane, and the measurement plane of the top view angle.
S2, the image display unit performs scaling processing on the shot sound generating equipment so that the sound generating equipment at the current visual angle is displayed in a proper range of an image display picture, and the image display unit is also used for calculating area data of the sound generating equipment at the current visual angle in the image display picture after scaling processing;
s3, dividing the image display picture into corresponding number of surface elements by a fixed point unit, respectively fixing points at corresponding positions in the surface elements (the fixed point is needed to be explained in the specification), and sending the fixed point positions to an infrared sensing module;
s4, the infrared sensing module takes a shooting surface of the shooting unit as an emitting surface, and emits a plurality of infrared rays towards the sounding equipment according to the fixed point position;
s5, detecting the same section position of the plurality of infrared rays by the sound intensity measuring module to obtain a plurality of sound intensity data corresponding to a plurality of point positions;
s6, repeating the steps S1-S5 aiming at the rest view angles of the sounding equipment;
and S7, calculating the total sound power of the sound generating device by the sound power calculating module according to the plurality of sound intensity data corresponding to the sound generating device at each view angle, the area data of the sound generating device at each view angle in the image display picture and the scaling factors corresponding to the sound generating device at each view angle.
Specifically:
in step S3, the fixed point unit equally divides the image display picture into corresponding number of surface elements, and the selection of the number of the surface elements comprises the following steps:
a. dividing an image display picture into a preset initial number of surface elements, respectively carrying out fixed points at the central positions of the surface elements, and sending the fixed point positions to an infrared sensing module;
the preset initial number can be set to 6, and can be specifically set according to actual situations.
b. Step S4-step S5 are executed based on the fixed point positions of the step a, so that a plurality of sound intensity data corresponding to a plurality of point positions corresponding to the number of the current face elements are obtained;
c. calculating to obtain a sound field non-uniform indication value based on a plurality of sound intensity data corresponding to the number of the current face elements
And judging whether the following formula is established:
wherein ,
the number of the surface elements is represented,
representing a constant factor;
wherein ,
represent the first
Sound intensity data corresponding to the individual surface elements,
total sound intensity data representing the measurement surface.
The setting of the constant factor can be referred to as shown in table 1 below:
table 1 constant factor setting table
It can be seen that, in this embodiment, the maximum value of C is 57 or 29, and when C takes 57, detection of all frequencies corresponding to the precision level can be satisfied, and when C takes 29, detection of all frequencies corresponding to the engineering level can be satisfied.
The setting table of the criteria and the constant factors can be seen in the section 1 of the sound power level of the noise source measured by the standard GB/T16404-1996 acoustic sound intensity method: measurement at discrete points.
d. If not, increasing the number of the current equally divided surface elements by one, re-executing the steps a-c, and if so, taking the number of the current equally divided surface elements as the final surface element number.
It should be noted that: the steps a to d are to determine the fixed point number on the measurement surface, and the same steps are required to be executed for each view angle of the sound generating device, so as to set the fixed point number on the measurement surface of each view angle. In addition, the method for selecting the number of the cells adopted by the invention is only used for detecting the sound source with directivity, and the sound field of the sound source with omni-directivity is uniform, and the sound source with directivity is non-uniform, so that the criterion adopted by the method for selecting the number of the cells is different from that adopted by the method for detecting the sound source with directivity.
In step S3, after dividing the image display screen into a corresponding number of bins, the selecting of the fixed point positions of each bin includes the following steps: A. filtering pretreatment is carried out on an original image of an image display picture so as to obtain an interference gray scale image;
B. binarizing the interference gray level image by a threshold segmentation method to obtain a binarized interference image, wherein the binarized interference image comprises a plurality of vertical interference fringes, and the interference fringes only have black and white gray level values as shown in FIG. 4;
the relation between the binarized interference image and the interference gray scale image satisfies the following conditions:
wherein ,
representing binarized stemsIn the image related to
The gray value at the location is a function of the gray value at the location,
representing the interference gray-scale pattern
The gray value at the location is a function of the gray value at the location,
the binarization threshold is represented, and in this embodiment, the value is 2.
C. Carrying out refinement treatment on a plurality of interference fringes in the binarized interference image to obtain a plurality of vertical refined interference lines;
and C, refining the plurality of interference fringes in the binarized interference image, wherein the step C comprises the following steps of:
selecting any pixel point to be thinned in the binarized interference image, taking the pixel point to be thinned as a center, and selecting 8 adjacent pixel points surrounding the pixel point to be thinned;
c2, judging whether the pixel points to be thinned are deleted or not based on the pixel values of the 9 pixel points;
and C3, repeating the steps C1-C2 until all pixel points in the binarized interference image cannot be deleted, so as to obtain a plurality of vertical refined interference lines, which can be shown by referring to FIG. 5.
By way of example, referring to FIG. 6, let p be 0 For the binary point to be thinned in the binary interference image, the adjacent 8 pixel points surrounding the pixel point to be thinned are p respectively 1 、p 2 、p 3 、p 4 、p 5 、p 6 、p 7 、p 8 By n (p) 0 ) Represents the number of non-0 pixels in 8 adjacent pixel points, s (p 0 ) Expressed as p 1 、p 2 、p 3 、p 4 、p 5 、p 6 、p 7 、p 8、 p 1 In a sequential sequence, the number of times the pixel changes from 0 to 1.
In step C2, based on the pixel values of the 9 pixel points, judging whether the following 4 conditions can be satisfied at the same time, if so, the pixel point p to be thinned is determined 0 Deletion:
（1）、2≤n（p 0 ）≤6；
（2）、s（p 0 ）=1；
（3）、p 1、 p 3 、p 7 at the same time equal to 0 or s (p 1 ）≠1；
（4）、p 1、 p 3 、p 5 At the same time equal to 0 or s (p 3 ）≠1；
wherein ,s（p1 ）、s（p 3 ) Is calculated based on the principle of calculation of s (p) 0 ) Is consistent with the calculation principle of (a), i.e. for p in FIG. 6 1 Or p 3 Point reselection wrapping the p 1 Or p 3 The 8 adjacent pixels of the dot are calculated as s (p 0 ) The 8 pixels are sequentially arranged, namely, the pixel at the middle position of the uppermost row is taken as the first pixel, and the number of times that the pixel changes from 0 to 1 is calculated by rotating one circle clockwise.
Further, the steps between the step C and the step D can also comprise the steps of: performing skeleton restoration treatment on the interference fringes after the refinement treatment, wherein the skeleton restoration treatment comprises the following steps:
identifying end points and branch points of the refined interference line, and presetting a branch importance weight;
starting from each branch point, tracking the pixel point weight of each branch and accumulating to obtain a branch accumulation weight of each branch;
branches with the branch cumulative weight smaller than the branch importance weight are removed.
The effect diagram after branch removal can be seen with reference to fig. 8.
D. A plurality of sampling lines penetrating through the whole binarized interference image are arranged at certain intervals in the direction perpendicular to the refined interference line so as to obtain a spatial coherence interferogram, wherein the spatial coherence interferogram comprises a plurality of sampling points, namely the intersection points of the sampling lines and the refined interference line, and the spatial coherence interferogram can be shown by referring to FIG. 7;
E. uniformly dividing the space coherence interferogram into space coherence sub-interferograms with the quantity consistent with the number of the finally determined surface elements;
F. and taking the sampling point position of which the sampling value is closest to a preset threshold value in the spatial coherence sub-interferogram as the fixed point position corresponding to the spatial coherence sub-interferogram.
That is, after the fixed point number is selected in step S3, in this embodiment, instead of using the center point of the equipartition surface element as the fixed point position, the sampling point position of all the sampling points in the spatial coherence sub-interferogram, whose acquisition value is closest to the preset threshold, is used as the fixed point position corresponding to the spatial coherence sub-interferogram, that is, the fixed point position of the corresponding surface element of the spatial coherence sub-interferogram, which has the advantages of better covering our measurement surface and improving our test precision.
In the above description, the spatial coherence sub-interferograms are positioned at the same time as the spatial coherence sub-interferograms, that is, at the same time as the spatial coherence sub-interferograms.
Similarly, in the above steps a to F, in order to determine the fixed point positions on the measurement surface, the same steps are required to be performed for each view angle of the sound generating device, so as to set the fixed point positions on the measurement surface of each view angle, and it should be noted that the set of point location positioning method is only used for detecting the omni-directional sound source, and because the omni-directional sound source is uniform, the set of point location positioning method is not necessary.
Assuming that the main view angle, the side view angle and the overlook angle measuring surface are divided into
The sound intensity data of the sound generating device measured by the surface elements and all the view angles are also
And if so, the relation between the sound power and the sound intensity of each bin is as follows:
wherein ,
represent the first
The acoustic power corresponding to each bin,
represent the first
Sound intensity data corresponding to the individual surface elements,
represent the first
Area data corresponding to each bin.
The total sound power of the sound generating device can thus be measured by measuring the total sound intensity surrounding the sound source enclosure. Because the sound intensity reflects the sound power of the unit area of the measuring surface, the normal component of the sound intensity along the curve direction is integrated on the whole closed curved surface, and the total sound power of the sound generating device can be obtained
。
wherein ,
the first of the sound intensity data representing all of the viewing angle measured sound emitting devices
The data of the sound intensity of the sound,
the number of sound intensity data of the sound generating devices measured by all view angles is represented,
indicating the corresponding magnification of the main viewing angle,
indicating the corresponding scaling factor of the side view angle,
indicating the scaling factor corresponding to the top view angle,
area data representing the main viewing angle sound emitting device in the image display screen,
area data representing the side view angle sound emitting device in the image display screen,
area data representing the top-view angle sound emitting device in the image display screen,
and the sum of area data of the three visual angle sounding devices in the image display screen is represented.
Therefore, the invention can realize automatic fixed point by additionally arranging the camera shooting unit, the image display unit, the fixed point unit and the infrared sensing module, and automatically calculate and obtain the total sound power of the sound generating device according to a plurality of sound intensity data corresponding to the sound generating device at each view angle, the area data of the sound generating device at each view angle in the image display picture and the scaling factor corresponding to the sound generating device at each view angle. The invention provides a scheme for determining the number of the face elements and the specific fixed point position, and the scheme can ensure the accuracy of the calculation of the total sound power of the sound generating equipment on the basis of the minimum point positions.
The above examples are merely illustrative of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention, and various modifications and improvements made by those skilled in the art to the technical solution of the present invention should fall within the protection scope of the present invention without departing from the design spirit of the present invention.
Claims (7)
1. A method of measuring acoustic power of an acoustic device, the method comprising the steps of:
s1, shooting sound equipment with corresponding visual angles by using a shooting unit, and displaying the sound equipment in an image display unit;
s2, scaling the shot sound generating equipment by the image display unit so that the sound generating equipment at the current visual angle occupies the whole image display picture as much as possible for display, and calculating area data of the sound generating equipment at the current visual angle in the image display picture after scaling;
s3, the fixed point unit equally divides the image display picture into corresponding number of surface elements, respectively carries out fixed points at corresponding positions in the surface elements, and sends the fixed point positions to the infrared sensing module;
s4, the infrared sensing module takes a shooting surface of the shooting unit as an emitting surface, and emits a plurality of infrared rays towards the sounding equipment according to the fixed point position;
s5, detecting the same section position of the plurality of infrared rays by the sound intensity measuring module to obtain a plurality of sound intensity data corresponding to a plurality of point positions;
s6, repeating the steps S1-S5 aiming at the rest view angles of the sounding equipment;
s7, calculating the total sound power of the sound generating device by the sound power calculating module according to the plurality of sound intensity data corresponding to the sound generating device at each view angle, the area data of the sound generating device at each view angle in the image display picture and the scaling factors corresponding to the sound generating device at each view angle;
in step S3, the fixed point unit equally divides the image display picture into corresponding number of surface elements, and the selection of the number of the surface elements comprises the following steps:
a. dividing an image display picture into a preset initial number of surface elements, respectively carrying out fixed points at the central positions of the surface elements, and sending the fixed point positions to an infrared sensing module;
b. step S4-step S5 are executed based on the fixed point positions of the step a, so that a plurality of sound intensity data corresponding to a plurality of point positions corresponding to the number of the current face elements are obtained;
c. calculating to obtain a sound field non-uniform indication value based on a plurality of sound intensity data corresponding to the number of the current face elements
And judging whether the following formula is established:
wherein ,
representing the number of face elements>
Representing a constant factor;
d. if not, adding one to the number of the current equally divided surface elements, re-executing the steps a-c, and if so, taking the number of the current equally divided surface elements as the final surface element number;
wherein ,
indicate->
Sound intensity data corresponding to the individual bin, +.>
Total sound intensity data representing the measurement face;
in step S3, after dividing the image display screen into a corresponding number of bins, the selecting of the fixed point positions of each bin includes the following steps:
A. preprocessing an original image of an image display picture to obtain an interference gray scale image;
B. binarizing the interference gray level image by adopting a threshold segmentation method to obtain a binarized interference image, wherein the binarized interference image comprises a plurality of vertical interference fringes;
C. carrying out refinement treatment on a plurality of interference fringes in the binarized interference image to obtain a plurality of vertical refined interference lines;
D. setting a plurality of sampling lines penetrating through the whole binarization interference image at certain intervals in the direction perpendicular to the thinning interference line so as to obtain a spatial coherence interferogram, wherein the spatial coherence interferogram comprises a plurality of sampling points, and the sampling points are the intersection points of the sampling lines and the thinning interference line;
E. uniformly dividing the space coherence interferogram into space coherence sub-interferograms with the quantity consistent with the number of the finally determined surface elements;
F. and taking the sampling point position of which the sampling value is closest to a preset threshold value in the spatial coherence sub-interferogram as the fixed point position corresponding to the spatial coherence sub-interferogram, namely the fixed point position of the corresponding bin of the spatial coherence sub-interferogram.
2. The method for measuring acoustic power of acoustic device according to claim 1, wherein in step B, the relationship between the binarized interference image and the interference gray scale map satisfies:
wherein ,
representing twoValuing +.>
Gray value at position +.>
Representing +.>
Gray value at position +.>
Representing a binarization threshold.
3. The method for measuring acoustic power of an acoustic device according to claim 1, wherein in the step C, the thinning process is performed on a plurality of interference fringes in the binarized interference image, and the method comprises the steps of:
selecting any pixel point to be thinned in the binarized interference image, taking the pixel point to be thinned as a center, and selecting 8 adjacent pixel points surrounding the pixel point to be thinned;
c2, judging whether the pixel points to be thinned are deleted or not based on the pixel values of the 9 pixel points;
and C3, repeating the steps C1-C2 until all pixel points in the binarized interference image cannot be deleted, so as to obtain a plurality of vertical refined interference lines.
4. The method for measuring the acoustic power of an acoustic device according to claim 1, further comprising the steps of: and performing skeleton restoration treatment on the interference fringes after the refinement treatment.
5. The method for measuring acoustic power of an acoustic device according to claim 4, wherein skeleton restoration processing is performed on the plurality of thinned interference fringes, comprising the steps of:
identifying end points and branch points of the refined interference line, and presetting a branch importance weight;
starting from each branch point, tracking the pixel point weight of each branch and accumulating to obtain a branch accumulation weight of each branch;
branches with the branch cumulative weight smaller than the branch importance weight are removed.
6. The method for measuring the acoustic power of the acoustic device according to claim 1, wherein in step S7, the calculation formula of the total acoustic power of the acoustic device is:
wherein ,
representing the total sound power of the sound emitting device +.>
The first of the sound intensity data representing all of the viewing angle measured sound emitting devices
Personal sound intensity data,/>
Number of sound intensity data representing all sound emitting devices measured at viewing angle,/for the sound emitting device>
Represents the corresponding magnification of the main viewing angle, +.>
Represents the scaling factor corresponding to the side view angle, +.>
Represents the scaling factor corresponding to the top view angle +.>
Area data representing the main viewing angle sound emitting device in an image display screen +.>
Area data representing side view angle sound emitting device in image display screen,/for>
Area data representing a top-view angle sound generating device in an image display screen, < >>
And the sum of area data of the three visual angle sounding devices in the image display screen is represented.
7. A sound power measuring system of sound equipment based on the sound power measuring method of sound equipment of any one of claims 1-6, characterized by comprising an infrared sensing module, a sound intensity measuring module, a shooting fixed point module and a sound power calculating module, wherein the shooting fixed point module comprises a shooting unit, an image display unit and a fixed point unit;
the shooting unit is used for shooting the sounding devices at all visual angles;
the image display unit is used for displaying the shot sound generating equipment, scaling the shot sound generating equipment so that the current visual angle sound generating equipment occupies the whole image display picture as much as possible for display, and calculating to obtain area data of the scaled sound generating equipment in the image display picture;
the fixed point unit is used for equally dividing the image display picture into corresponding number of surface elements, respectively carrying out fixed points at corresponding positions in the surface elements, and sending the fixed point positions to the infrared sensing module;
the infrared sensing module is used for emitting a plurality of infrared rays towards the sounding device according to the fixed point position by taking the shooting surface of the shooting unit as an emitting surface;
the sound intensity measuring module is used for detecting and obtaining a plurality of sound intensity data corresponding to a plurality of point positions at the same tangent plane position of a plurality of infrared rays;
and the sound power calculation module is used for calculating and obtaining the total sound power of the sound generating device according to the plurality of sound intensity data corresponding to the sound generating device at each view angle, the area data of the sound generating device at each view angle in the image display picture and the scaling factors corresponding to the sound generating device at each view angle.
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