CN101986723B - Test system and test method for pressure gradient microphone - Google Patents
Test system and test method for pressure gradient microphone Download PDFInfo
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- CN101986723B CN101986723B CN201010528196.3A CN201010528196A CN101986723B CN 101986723 B CN101986723 B CN 101986723B CN 201010528196 A CN201010528196 A CN 201010528196A CN 101986723 B CN101986723 B CN 101986723B
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Abstract
The invention provides a test system for a pressure gradient microphone, which comprises a sound source, a monitoring microphone separated from the sound source by a certain distance and the pressure gradient microphone to be tested, wherein the test system for the pressure gradient microphone further comprises a travelling wave tube with smooth inner wall, one end of the travelling wave tube is in butt joint with the sound source, an acoustic wedge is arranged at the other end, a sound-absorbing material is arranged in the acoustic wedge, the monitoring microphone and the pressure gradient microphone to be tested are inserted into the travelling wave tube, and sound pressure emitted by the sound source reaches the monitoring microphone and the pressure gradient microphone to be tested through the travelling wave tube. The test system for the pressure gradient microphone can be used for large-batch testing on a production line and realize high testing precision.
Description
[technical field]
The present invention relates to a kind of pressure gradient microphone test macro and method of testing, relate in particular to a kind of travelling wave tube test macro and method of testing thereof for test pressure differential microphone.
[background technology]
Mobile communication technology is rapidly developed in recent years.Consumer uses mobile communication equipment more and more, the requirement of mobile communication equipment is not only satisfied with and can be conversed, and want to provide high-quality communication effect.Especially the development of Technology of Mobile Multimedia, the speech quality of mobile phone becomes more important.Pressure gradient microphone is as one of transducer of mobile phone, and the quality of its performance directly affects speech quality.Therefore it is very important before pressure gradient microphone is used, its performance being tested.
Pressure gradient microphone test philosophy is to make the vibrating diaphragm two sides of pressure gradient microphone be subject to sound, thereby makes pressure gradient microphone produce response to pressure difference.Relevant pressure gradient microphone test macro is in the free field in anechoic chamber, pressure gradient microphone to be tested, and must guarantee to be provided with certain measuring distance while testing, and measuring distance is greater than 1m.But this test macro is not suitable for the test in enormous quantities of producing on line.
Therefore, be necessary to provide a kind of new pressure gradient microphone test macro to address the above problem.
[summary of the invention]
The technical problem that the present invention need solve is to provide a kind of can be applicable to produce test in enormous quantities and the high pressure gradient microphone test macro of measuring accuracy on line.
According to above-mentioned technical problem, designed a kind of pressure gradient microphone test macro, its objective is such realization: a kind of pressure gradient microphone test macro, comprise sound source and with described sound source monitoring microphone and pressure gradient microphone to be measured separated by a distance.Wherein, described pressure gradient microphone test macro also comprises the travelling wave tube of inner wall smooth, and dock with described sound source described travelling wave tube one end, the other end is provided with wedge absorber, in described wedge absorber, is provided with sound-absorbing material.Described monitoring microphone and pressure gradient microphone to be measured are inserted in travelling wave tube, and the acoustic pressure that described sound source is sent arrives described monitoring microphone and described pressure gradient microphone to be measured by travelling wave tube.
Preferably, described travelling wave tube is provided with tube wall, and described tube wall is provided with some instrument connections that run through described tube wall, and described monitoring microphone and described pressure gradient microphone to be measured are inserted in described travelling wave tube by described instrument connection.
Preferably, described travelling wave tube is made with pmma material, and its cross section is square.
Preferably, the length of described monitoring microphone and a wedge absorber of described wedge absorber distance.
Preferably, described sound source is full range speaker, 1/2 cun of microphone of standard that described monitoring microphone is pressure type.
Preferably, described pressure gradient microphone test macro is also provided with coupling cavity, described travelling wave tube dock with described sound source by connecting described coupling cavity, its cross sectional shape of one end that described coupling cavity docks with described sound source and described sound source shape is consistent, and its cross sectional shape of one end of described travelling wave tube connection and the shape of described travelling wave tube consistent.
Preferably, described instrument connection comprise some for test the first instrument connection of pressure gradient microphone to be measured and with described the first instrument connection not at conplane the second instrument connection, described monitoring microphone is inserted in described travelling wave tube by described the second instrument connection.
Preferably, described the first instrument connection is round table-like, and it is provided with 3 and equidistant being separated by.
The present invention also provides a kind of method of testing based on above-mentioned pressure gradient microphone test macro, it is characterized in that: the method comprises the steps:
One sound source is provided, and described sound source is full range speaker;
One monitoring microphone is provided, and itself and described sound source are separated by a distance;
One travelling wave tube is provided, its one end is connected with described sound source, the other end is provided with sound-absorbing wedge, in described sound-absorbing wedge, be provided with sound-absorbing material, described travelling wave tube be provided with some the first instrument connections and with described the first instrument connection not at conplane the second instrument connection, described the first instrument connection comprises the first instrument connection first, the first instrument connection second and the first instrument connection third;
Some pressure gradient microphones to be measured are provided;
Audio analyzer is provided, and it is connected to described sound source, monitoring microphone and pressure gradient microphone to be measured;
Described monitoring microphone and described pressure gradient microphone to be measured are inserted in the described wave duct of row by the second instrument connection and the first instrument connection first respectively, described the first instrument connection second and described the first instrument connection third that do not insert microphone to be measured are sealed, the acoustic pressure of more described sound source being sent arrives described monitoring microphone and described pressure gradient microphone to be measured by described travelling wave tube, by audio analyzer analytical test result;
In like manner, described pressure gradient microphone to be measured is changed to the first instrument connection second or the first instrument connection third is tested, analyze compare test result, the location positioning that approaches required theoretical value take the test value of pressure gradient microphone to be measured is most optimum test position.
Preferably, described pressure gradient microphone to be measured carries out frock, makes its top be set to cylindrical rod, and middle part is the round table-like stopper matching with described the first instrument connection, and bottom is the fixing described pressure gradient microphone to be measured of a thin bar.
Compared with correlation technique, it is high that pressure gradient microphone test macro of the present invention can be used for producing test in enormous quantities and measuring accuracy on line.
[accompanying drawing explanation]
Fig. 1 is the three-dimensional structure diagram of pressure gradient microphone test macro of the present invention.
Fig. 2 is along A-A line part cut-away view in Fig. 1.
Structure chart when Fig. 3 is pressure gradient microphone test macro use of the present invention, it is connected with audio analyzer.
Fig. 4 is the tool structure figure of pressure gradient microphone to be measured of the present invention.
[embodiment]
Below in conjunction with drawings and embodiments, the invention will be further described.
As Figure 1-3, a kind of pressure gradient microphone test macro 1, comprise sound source 5 and with sound source 5 monitoring microphone 6 and pressure gradient microphone to be measured 7 separated by a distance.Wherein, pressure gradient microphone test macro 1 also comprises the travelling wave tube 3 of inner wall smooth, and dock with sound source 5 travelling wave tube 3 one end, the other end is provided with conical wedge absorber 2.The length of wedge absorber 2 is determined by the low-frequency cut-off frequency of sound wave.In wedge absorber 2, be provided with sound-absorbing material.Monitoring microphone 6 and pressure gradient microphone to be measured 7 are inserted in travelling wave tube 3, and the acoustic pressure that sound source 5 is sent arrives described monitoring microphone 6 and pressure gradient microphone to be measured 7 by travelling wave tube 3.
In present embodiment, travelling wave tube 3 is provided with tube wall 33, and tube wall 33 is provided with some instrument connections (not label) that run through tube wall 33, and monitoring microphone 6 and pressure gradient microphone to be measured 7 are inserted in travelling wave tube 3 by instrument connection.Concrete, instrument connection comprise some for test the first instrument connection 31 of pressure gradient microphone 7 to be measured and with the first instrument connection 31 not at conplane the second instrument connection 32, pressure gradient microphone 7 to be measured is inserted in travelling wave tube 3 by the first instrument connection 31, and monitoring microphone 6 is inserted in travelling wave tube 3 by the second instrument connection 32.Preferably, the first instrument connection 31 is provided with 3 and equidistant being separated by, and it is shaped as round table-like, and this set has good test comparative effectiveness.Certainly, the first instrument connection can also be made as other quantity, and it is equidistant that the distance between it is also not necessarily wanted.In the present invention, so-called round table-like referring on the basis of cone removed tip, makes the area of its upper surface be less than the area of lower surface.
The inner wall smooth of travelling wave tube 3 is that the viscous damping in order to prevent tube wall 33 causes decay to sound wave, thereby reduces test error.In order to make the making of travelling wave tube 3 easy to process, it is foursquare lucite tube that travelling wave tube 3 adopts pmma material to make cross section.Certainly, travelling wave tube also can be made with other material, and its cross section can be also rectangle, circle or other shape, and this is all feasible.
Concrete, present embodiment describes as an example of test frequency range scope 200Hz-5000Hz example, and this is the normal working band scope of pressure gradient microphone in fact, and it is also feasible exceeding this frequency band range.The tube wall 33 of travelling wave tube 3 is provided with certain thickness, its objective is the defening effect that can better guarantee travelling wave tube 3, prevents that outside noise from disturbing.Consider the factors such as defening effect and processing cost, the thickness of travelling wave tube 3 is made as 1cm, and other thickness is also fine.
In order to test required condition, in travelling wave tube 3, sound wave is designed to plane wave, thereby can be approximately, microphone to be measured is placed in to infinity free field, can meet so the required condition of test.And in travelling wave tube 3 except plane wave, also likely have higher modes ripple.There is a normal mode in corresponding a pair of subscript value (m, n), is called (m, n) inferior normal mode.Only as f > f
mntime higher-order wave just exist, wherein, f is frequency of sound wave, f
mnbe called the normal frequency of (m, n) pattern:
Wherein, c
0the velocity of sound, l
x, l
ybe respectively the length in travelling wave tube 3 cross sections and wide.For guaranteeing to only have plane wave in travelling wave tube 3, there is no higher modes ripple, frequency of sound wave must be less than the cut-off frequency of pipe, that is:
Wherein, f
00for sound frequencies, f is frequency of sound wave, l
xyfor travelling wave tube internal diameter.Because cross section is square travelling wave tube, l
x=l
y=l
xy, therefore, when meeting formula (2), only have f
00frequency wave exists, i.e. plane wave.
The thickness of the high frequency critical value major decision travelling wave tube of sound wave, is worth higher pipe thinner, and tube wall decay increases, and difficulty of processing increases simultaneously.Work as fh=5kHz, l
x=l
y=l
xytime, in conjunction with formula (1) and (2), can obtain l
xy< 0.0343m, needs the internal diameter that meets travelling wave tube 3 to be less than 3.43cm.In fact, if high frequency critical value difference, the l drawing
xyvalue is also different, but principle is the same.
Therefore,, according to test frequency range computation, present embodiment is made as 3cm the internal diameter of travelling wave tube 3.In fact it is all feasible that the internal diameter that meets travelling wave tube is less than 3.43cm.When the internal diameter of travelling wave tube 3 is made as 3cm, meet the cut-off frequency that frequency of sound wave is less than travelling wave tube 3, can guarantee like this to only have plane wave in travelling wave tube 3, there is no high order harmonic component, and then increased the accuracy of test.
The length of the low frequency critical value major decision wedge absorber 2 of sound wave.When low frequency fl=200Hz, the length of wedge absorber 2
λ is wave length of sound,
therefore can draw l
a=0.43m.In order to reduce the test error at critical value place, wedge absorber 2 length that arrange in present embodiment are 50cm.Certainly, not its length is necessarily made as 50cm.
Wedge absorber 2 can not reach 100% absorption sound wave, and its front end must exist sound wave reflection, thereby reflected wave can mutually be interfered and make that sound field is inhomogeneous and then to make to monitor microphone 6 inaccurate to the feedback of sound field with the sound wave of sound source 5.Therefore, monitoring microphone 6 and the length of wedge absorber 2 apart from a wedge absorber 2, like this can the impact of anti-reflection ejected wave on sound field.
Because pressure gradient microphone 7 to be measured exists near-field effect, its sensitivity changes with variable in distance, thereby causes test error.Should reduce the test error that near-field effect causes as far as possible, sound source and microphone standoff distance to be measured need be made as to far-field range, far field condition is kr > > 1, and wherein k is wave number,
r is the axial distance of pressure gradient microphone 7 to be measured apart from sound source 5, according to this far field condition, calculates r > > 0.27m.It is 40cm that r is set in present embodiment, the distance that this also just arranges at random after satisfying condition.Concrete, the first instrument connection second 31b and pressure gradient microphone to be measured 7 are apart from 40cm.
In addition, present embodiment also offers respectively the first instrument connection first 31a and first instrument connection the third 31c on the both sides of the first instrument connection second 31b.Under similarity condition, can make comparison to test result like this, further reduce test error.More the first instrument connections 31 can also be set certainly.Preferably, equi-spaced apart between the first instrument connection first 31a, the first instrument connection second 31b and first instrument connection the third 31c, at a distance of 20cm.
Due to the setting of the parts such as wedge absorber 2, the first instrument connection 31, concrete, the length that arranges of travelling wave tube 3 is not less than 140cm.Certainly, the parts such as wedge absorber 2, the first instrument connection 31 arrange difference, and the length of its travelling wave tube also changes, but principle is all the same.
Pressure gradient microphone test macro 1 is also provided with coupling cavity 4, travelling wave tube 3 docks with sound source 5 by connecting coupling cavity 4, its cross sectional shape of one end that coupling cavity 4 docks with sound source 5 and the shape of sound source 5 is consistent, and the shape of its cross sectional shape of one end of connecting of described travelling wave tube 3 and described travelling wave tube 3 consistent.Such as, in present embodiment, sound source 5 is selected rectangular full range speaker, and travelling wave tube 3 is square for cross section, and its cross section, one end that its cross section, one end that coupling cavity 4 docks with sound source 5 is rectangle, connect with travelling wave tube 3 is for square.The cross section of coupling cavity 4 changes continuously, by rectangle, is transited into gradually square, can reduce like this wall reflection in propagation process of sound wave, makes acoustic energy transmission coefficient reach maximum, improves test accuracy.
As marked Fig. 2-3, the present invention also provides a kind of method of testing based on above-mentioned pressure gradient microphone test macro 1, it is characterized in that: the method comprises the steps:
One sound source 5 is provided, and sound source 5 is full range speaker;
One monitoring microphone 6 is provided, and itself and sound source 5 are separated by a distance;
One travelling wave tube 3 is provided, and its one end is connected with sound source 5, the other end is provided with sound-absorbing wedge 2, in sound-absorbing wedge 2, is provided with sound-absorbing material, travelling wave tube 3 be provided with some the first instrument connections 31 and with the first instrument connection 31 not at conplane the second instrument connection 32.The first instrument connection 31 comprises the first instrument connection first 31a, the first instrument connection second 31b, first instrument connection the third 31c.
Some pressure gradient microphones to be measured 7 are provided;
Audio analyzer 8 is provided, and it is connected to sound source 5, monitoring microphone 6 and pressure gradient microphone to be measured 7;
Monitoring microphone 6 and the good pressure gradient microphone to be measured 7 of frock are inserted in travelling wave tube 3 by the second instrument connection 32 and the first instrument connection first 31a respectively, will insert the first instrument connection second 31b and the first instrument connection third 31c sealing of microphone 7 to be measured.The acoustic pressure of again sound source 5 being sent arrives monitoring microphone 6 and pressure gradient microphone to be measured 7 by travelling wave tube 3, by audio analyzer 8 analytical test results.In like manner, pressure gradient microphone 7 to be measured is changed to the first instrument connection second 31b or first instrument connection the third 31c tests, analyze compare test result, the location positioning that approaches required theoretical value take the test value of pressure gradient microphone 7 to be measured is most optimum test position.
More convenient in order to test, measuring accuracy is higher, as shown in Figure 4, pressure gradient microphone 7 to be measured is carried out to frock, and making frock top that diameter is set is the cylindrical rod 71 of 1/2 cun, and certainly, its size and dimension can arrange difference as required.The round table-like stopper 72 of middle part for matching with the first instrument connection 31, the plug seal better effects if of this structure.Bottom is the fixing pressure gradient microphone 7 to be measured of a thin bar 73.Concrete, pressure gradient microphone to be measured 7 good frock is inserted in travelling wave tube 3, be located at the interior center of travelling wave tube 3 and make the vibrating diaphragm (not shown) of pressure gradient microphone 7 to be measured vertical with the axis of travelling wave tube 3, can guarantee that like this sound wave is to be applied on the vibrating diaphragm of microphone 7 to be measured with 0 degree incidence angle, reduces test distortion degree.
Compared with correlation technique, pressure gradient microphone test macro of the present invention is little easy to use because of its volume, and not be used in anechoic chamber and uses, and can be used for producing test in enormous quantities and measuring accuracy on line high.
Above-described is only embodiments of the present invention, at this, it should be pointed out that for the person of ordinary skill of the art, without departing from the concept of the premise of the invention, can also make improvement, but these all belongs to protection scope of the present invention.
Claims (9)
1. a pressure gradient microphone test macro, comprise sound source and with described sound source monitoring microphone and pressure gradient microphone to be measured separated by a distance, and be connected in described sound source, the audio analyzer for analytical test result of monitoring microphone and pressure gradient microphone to be measured, it is characterized in that: described pressure gradient microphone test macro also comprises the travelling wave tube of inner wall smooth, dock with described sound source described travelling wave tube one end, the other end is provided with wedge absorber, in described wedge absorber, be provided with sound-absorbing material, described monitoring microphone and pressure gradient microphone to be measured are inserted in travelling wave tube, described travelling wave tube be provided with some the first instrument connections and with described the first instrument connection not at conplane the second instrument connection, described the first instrument connection comprises the first instrument connection first, the first instrument connection second and the first instrument connection third, described monitoring microphone and described pressure gradient microphone to be measured are inserted in the described wave duct of row by the second instrument connection and the first instrument connection first respectively, described the first instrument connection second and described the first instrument connection third that do not insert microphone to be measured seal, the acoustic pressure that described sound source is sent arrives described monitoring microphone and described pressure gradient microphone to be measured by travelling wave tube, by audio analyzer analytical test result, in like manner, described pressure gradient microphone to be measured changes to the first instrument connection second or the first instrument connection third is tested, analyze compare test result, the location positioning that approaches most required theoretical value take the test value of pressure gradient microphone to be measured is optimum test position.
2. pressure gradient microphone test macro according to claim 1, is characterized in that: described travelling wave tube is provided with tube wall, described first, second instrument connection runs through described tube wall.
3. pressure gradient microphone test macro according to claim 2, is characterized in that: described travelling wave tube pmma material is made, and its cross section is square.
4. pressure gradient microphone test macro according to claim 3, is characterized in that: the length of described monitoring microphone and a wedge absorber of described wedge absorber distance.
5. pressure gradient microphone test macro according to claim 4, is characterized in that: described sound source is full range speaker, 1/2 cun of microphone of standard that described monitoring microphone is pressure type.
6. pressure gradient microphone test macro according to claim 5, it is characterized in that: described pressure gradient microphone test macro is also provided with coupling cavity, described travelling wave tube dock with described sound source by connecting described coupling cavity, its cross sectional shape of one end that described coupling cavity docks with described sound source and described sound source shape is consistent, and its cross sectional shape of one end of described travelling wave tube connection and the shape of described travelling wave tube consistent.
7. pressure gradient microphone test macro according to claim 6, is characterized in that: described the first instrument connection is round table-like, and it is provided with 3 and equidistant being separated by.
8. a method of testing for pressure gradient microphone, is characterized in that: the method comprises the steps:
One sound source is provided, and described sound source is full range speaker;
One monitoring microphone is provided, and itself and described sound source are separated by a distance;
One travelling wave tube is provided, its one end is connected with described sound source, the other end is provided with sound-absorbing wedge, in described sound-absorbing wedge, be provided with sound-absorbing material, described travelling wave tube be provided with some the first instrument connections and with described the first instrument connection not at conplane the second instrument connection, described the first instrument connection comprises the first instrument connection first, the first instrument connection second and the first instrument connection third;
Some pressure gradient microphones to be measured are provided;
Audio analyzer is provided, and it is connected to described sound source, monitoring microphone and pressure gradient microphone to be measured;
Described monitoring microphone and described pressure gradient microphone to be measured are inserted in the described wave duct of row by the second instrument connection and the first instrument connection first respectively, described the first instrument connection second and described the first instrument connection third that do not insert microphone to be measured are sealed, the acoustic pressure of more described sound source being sent arrives described monitoring microphone and described pressure gradient microphone to be measured by described travelling wave tube, by audio analyzer analytical test result;
In like manner, described pressure gradient microphone to be measured is changed to the first instrument connection second or the first instrument connection third is tested, analyze compare test result, the location positioning that approaches required theoretical value take the test value of pressure gradient microphone to be measured is most optimum test position.
9. the method for testing of pressure gradient microphone according to claim 8, it is characterized in that: described pressure gradient microphone to be measured carries out frock, make its top be set to cylindrical rod, middle part is the round table-like stopper matching with described the first instrument connection, and bottom is the fixing described pressure gradient microphone to be measured of a thin bar.
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| CN102395095A (en) * | 2011-12-06 | 2012-03-28 | 歌尔声学股份有限公司 | Test method of omnidirectional microphone and test equipment thereof |
| TWI429298B (en) * | 2013-01-29 | 2014-03-01 | Hong Xiang Technology | Microphone calibration method |
| CN109870505A (en) * | 2017-12-01 | 2019-06-11 | 中国飞机强度研究所 | It is a kind of using dynamic speaker as the portable travelling-wave tubes experimental rig of sound source |
| CN109121062B (en) * | 2018-10-17 | 2023-01-13 | 杭州兆华电子股份有限公司 | High sound pressure microphone testing arrangement |
| CN113615212B (en) * | 2019-07-15 | 2024-04-12 | 中科新悦（苏州）科技有限公司 | High-sound-pressure microphone calibration device, system and method |
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| KR100904162B1 (en) * | 2009-01-13 | 2009-06-22 | 에버테크노 주식회사 | Apparatus for transferring parts of microphone test system |
| CN201403203Y (en) * | 2009-03-31 | 2010-02-10 | 比亚迪股份有限公司 | Microphone electro-acoustic testing system |
| CN101651920A (en) * | 2009-06-19 | 2010-02-17 | 瑞声声学科技(深圳)有限公司 | Microphone distortion test system |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| KR100904162B1 (en) * | 2009-01-13 | 2009-06-22 | 에버테크노 주식회사 | Apparatus for transferring parts of microphone test system |
| CN201403203Y (en) * | 2009-03-31 | 2010-02-10 | 比亚迪股份有限公司 | Microphone electro-acoustic testing system |
| CN101651920A (en) * | 2009-06-19 | 2010-02-17 | 瑞声声学科技(深圳)有限公司 | Microphone distortion test system |
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