Microelectronic microphone free field sensitivity testing device

Abstract

The utility model discloses a microelectronic microphone free field sensitivity testing device, which belongs to the field of microphones and comprises a testing sound source, a reference microphone and a silencing groove. The silencing groove is in a hollow cuboid shape with an opening in the upper portion, a composite sound absorption component is laid on the inner wall of the silencing groove, and the testing sound source is located in the silencing groove and used for sending out pulse signals; a three-dimensional positioning device is arranged above the silencing groove, the three-dimensional positioning device is connected with a mounting seat, four side walls and the bottom of the lower part of the mounting seat are respectively provided with a mounting position for mounting a reference microphone, and the mounting positions can be detachably connected with the reference microphone. And the reference microphone is driven by the three-dimensional positioning device to move to be aligned with the sound center of the test sound source. According to the utility model, rapid and accurate positioning of the test sound source and the reference microphone can be realized, a full-frequency-band sound absorption effect covering high, medium and low frequency bands can be realized, the sound absorption coefficient at the frequency bands above 500Hz is greater than 0.99, and the test precision of the sensitivity of the microelectronic microphone can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of microphones, in particular to a free-field sensitivity testing device for a microelectronic microphone. Background Art

[0002] At present, for the test of the free-field sensitivity of a microelectronic microphone, the microelectronic microphone and the reference microphone unit are installed at appropriate positions in a free-field device. The test sound source is installed on a round rod. The distance between the microelectronic microphone and the test sound source is greater than one meter, and the sensitivity of the reference microphone unit is known. By comparing the test output signals of the microelectronic microphone and the reference microphone unit, the free-field sensitivity of the microelectronic microphone is calculated. However, this existing test method for microelectronic microphones requires a large free-field device, and it is not easy to coaxialize the test sound source and the microphone, which has the disadvantages of high test cost and low test accuracy.

[0003] In addition, the test sound source generally emits a continuous signal, which will cause the superposition of the direct signal and part of the reflected signal, and it is impossible to distinguish the two signals in the time domain, affecting the measurement accuracy. Summary of the Utility Model

[0004] The purpose of the utility model is to provide a free-field sensitivity testing device for a microelectronic microphone that solves the above problems, has low test cost and high accuracy.

[0005] In order to achieve the above purpose, the technical solution adopted by the utility model is as follows: A free-field sensitivity testing device for a microelectronic microphone includes a test sound source and a reference microphone, and also includes a sound absorption groove;

[0006] The sound absorption groove is a hollow cuboid with an open upper part, and the inner wall is lined with a composite sound absorption member. The composite sound absorption member is a plate-shaped multi-layer structure, which is successively a protective hole plate layer, a glass wool layer, a micro-perforated layer, a hollow layer and a back plate layer from top to bottom. When laying, the protective hole plate layer faces the center of the sound absorption groove, and the back plate layer contacts the sound absorption groove;

[0007] The test sound source is located in the sound absorption groove and is used to emit pulse signals;

[0008] A three-dimensional positioning device is arranged above the sound absorption groove. The three-dimensional positioning device is connected to a mounting seat. Each of the four side walls and the bottom of the lower part of the mounting seat is provided with a mounting position for mounting the reference microphone. The mounting position can be detachably connected to the reference microphone, and the reference microphone is driven by the three-dimensional positioning device to move to align with the sound center of the test sound source.

[0009] Preferably: The protective hole plate layer is perforated, the aperture is 2 mm to 4 mm, and the perforation rate is 20% to 25%;

[0010] The thickness of the glass wool layer and the hollow layer is 40mm to 60mm;

[0011] The micro-perforated layer is perforated with a pore diameter of 1mm and a perforation rate of 2.5% to 3.5%.

[0012] Preferably: the pore diameter of the protective hole plate is 3mm and the perforation rate is 25%;

[0013] The thickness of the glass wool layer and the hollow layer is 50mm;

[0014] The pore diameter of the micro-perforated layer is 1mm and the perforation rate is 3%.

[0015] Preferably: a coordinate system is established with the center of the upper surface of the sound absorption groove, the long side of the sound absorption groove is in the X-axis direction, the short side is in the Y-axis direction, and the vertical direction is the Z-axis direction;

[0016] The three-dimensional positioning device includes an X-axis translation mechanism, a Y-axis translation mechanism and a Z-axis translation mechanism, which are used to drive the mounting seat to move and position three-dimensionally in the sound absorption groove;

[0017] The three-dimensional positioning device is provided with an emergency stop button.

[0018] Compared with the prior art, the advantages of the present utility model are as follows:

[0019] (1) A three-dimensional positioning device is provided to drive the reference microphone or the microelectronic microphone to move so that it is aligned with the sound center of the test sound source located in the sound absorption groove, which can realize the rapid positioning of the microphone and the test sound source. Since the test sound source can be arranged on the inner side wall and the bottom of the sound absorption groove, mounting positions are provided on the four side surfaces and the bottom of the lower part of the mounting seat. The tester can select to place the reference microphone or the microelectronic microphone in one of the mounting positions according to the actual position of the test sound source. Based on this three-dimensional positioning device, the positioning accuracy of the present utility model is better than 0.1mm.

[0020] (2) A composite sound absorption member is laid in the sound absorption groove. In the present utility model, the composite sound absorption member is composed of a low-frequency resonator and multiple layers of porous materials with different operating frequencies, realizing the sound absorption effect covering the full frequency range of high, medium and low frequencies. The sound absorption coefficient is greater than 0.99 in the frequency band above 500Hz, and the overall thickness can be controlled to 100mm.

[0021] (3) For the test sound source, a pulse signal is used to replace the original continuous signal. By using the time difference between the direct signal and the reflected signal arriving at the microphone and applying time filtering technology, the reflected signal is filtered out to obtain an accurate test signal, thereby improving the test accuracy of the sensitivity of the microelectronic microphone.

[0022] In summary, when calibrating the free-field sensitivity of the microelectronic microphone, the present utility model has the advantages of low test cost and high accuracy. Description of the Drawings

[0023] Figure 1 This is a schematic structural view of the present utility model;

[0024] Figure 2 This is a cross-sectional view of the composite sound-absorbing member;

[0025] Figure 3 This is a schematic diagram of pulse signal filtering.

[0026] In the figure: 1, sound absorption groove; 2, composite sound-absorbing member; 3, protective hole panel layer; 4, glass wool layer; 5, micro-perforated layer; 6, hollow layer; 7, back panel layer; 8, mounting seat; 9, mounting position; 10, X-axis translation mechanism; 11, Y-axis translation mechanism; 12, Z-axis translation mechanism; 13, direct signal; 14, reflected signal. Specific embodiments

[0027] The present utility model will be further described below in conjunction with embodiments and the accompanying drawings.

[0028] Embodiment 1: Refer to Figures 1 to 3 , a free-field sensitivity test device for a microelectronic microphone, including a test sound source and a reference microphone, and further including a sound absorption groove 1;

[0029] The sound absorption groove 1 is a hollow cuboid with an open top, and the inner wall is lined with a composite sound-absorbing member 2. The composite sound-absorbing member 2 is a plate-shaped multi-layer structure, which from top to bottom are a protective hole panel layer 3, a glass wool layer 4, a micro-perforated layer 5, a hollow layer 6 and a back panel layer 7. When laying, the protective hole panel layer 3 faces the center of the sound absorption groove 1, and the back panel layer 7 is in contact with the sound absorption groove 1;

[0030] The test sound source is located in the sound absorption groove 1 and is used to emit pulse signals;

[0031] Above the sound absorption groove 1 is provided a three-dimensional positioning device. The three-dimensional positioning device is connected to a mounting seat 8. Each of the four side walls and the bottom of the lower part of the mounting seat 8 is provided with a mounting position 9 for mounting the reference microphone. The mounting position 9 can be detachably connected to the reference microphone, and the reference microphone is driven by the three-dimensional positioning device to move to align with the sound center of the test sound source.

[0032] The method for testing the sensitivity of a microelectronic microphone with the present utility model is as follows:

[0033] S1, select a microelectronic microphone to be tested for sensitivity;

[0034] S2, first install the test sound source at a suitable position in the sound absorption groove 1. Assume it is on one side wall of the sound absorption groove 1. Install the reference microphone on the mounting position 9 opposite to this side wall, and control the three-dimensional positioning device to move until the reference microphone is aligned with the sound center of the test sound source;

[0035] In S3, the pulse signal emitted by the test sound source is received by the reference microphone.

[0036] In S4, remove the reference microphone, install the microelectronic microphone, and perform the test again according to step S3.

[0037] In S5, since the sensitivity of the reference microphone is known, compare the signals received by the microelectronic microphone and the reference microphone through the comparison method, and calculate the free-field sensitivity of the microelectronic microphone.

[0038] Example 2: Refer to Figures 1 to 3 , on the basis of Example 1, the protective hole plate layer 3 is perforated, the aperture is 2 mm to 4 mm, and the perforation rate is 20% to 25%;

[0039] The thickness of the glass wool layer 4 and the hollow layer 6 is 40 mm to 60 mm;

[0040] The micro-perforated layer 5 is perforated, the aperture is 1 mm, and the perforation rate is 2.5% to 3.5%.

[0041] More optimal parameters are: the aperture of the protective hole plate is 3 mm, the perforation rate is 25%; the thickness of the glass wool layer 4 and the hollow layer 6 is 50 mm; the aperture of the micro-perforated layer 5 is 1 mm, and the perforation rate is 3%.

[0042] Regarding the three-dimensional positioning device: establish a coordinate system with the center of the upper surface of the anechoic tank 1 as the origin, the long side of the anechoic tank 1 as the X-axis direction, the short side as the Y-axis direction, and the vertical direction as the Z-axis direction; the three-dimensional positioning device includes an X-axis translation mechanism 10, a Y-axis translation mechanism 11, and a Z-axis translation mechanism 12, which are used to drive the mounting seat 8 to move and position three-dimensionally in the anechoic tank 1; the three-dimensional positioning device is provided with an emergency stop button. Pressing the emergency stop button will immediately stop the motor and abort the current command. The emergency stop button will not release the holding state of the motor, but only stop the movement in a fast deceleration manner, which can prevent damage to the components inside the present utility model.

[0043] Regarding the test sound source, since a pulse signal is emitted, the arrival times of the direct signal 13 and the reflected signal 14 at the receiving point where the microphone is located are different, and the signals are not continuous, as Figure 3 shown, so only the unwanted reflected signal 14 needs to be filtered out by time-domain wave selection to achieve accurate measurement of the free-field sensitivity. As Figure 3 the dotted line area in is the time selection window area, and only the signals within the window are selected.

[0044] Example 3: Refer to Figures 1 to 3, on the basis of Embodiment 1, the inner diameter size of the silencing groove 1 is set to 3m×2m, which is used to arrange the test sound source, reference microphone, and microelectronic microphone. The LS2 type microphone is used as the reference microphone to test the free-field sensitivity of the microelectronic microphone above the pulse signal frequency of 500 Hz. Compared with the original measurement method using continuous signals and manual positioning, the measurement accuracy has been improved, and the measurement expanded uncertainty has been improved from 0.40 dB to 0.25 dB. At the same time, the construction cost of the free sound field device is reduced by about 50%.

[0045] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A microelectronic microphone free-field sensitivity test device, comprising a test sound source and a reference microphone, characterized in that: Also included are sound-absorbing grooves; The muffler is in the shape of a hollow cuboid with an open top, and a composite sound-absorbing component is laid on the inner wall. The composite sound-absorbing component is a plate-like multi-layer structure, which includes a faceplate layer, a glass wool layer, a micro-perforated layer, a hollow layer and a back plate layer from top to bottom. When laid, the faceplate layer faces the center of the muffler, and the back plate layer contacts the muffler; The test sound source is located in the muffler tank and is used to send out a pulse signal; A three-dimensional positioning device is provided above the silencer groove, and the three-dimensional positioning device is connected to a mounting seat. The four side walls and the bottom of the lower part of the mounting seat are each provided with a mounting position for mounting a reference microphone. The mounting position can be detachably connected to the reference microphone, and the reference microphone is driven by the three-dimensional positioning device to move to align with the sound center of the test sound source.

2. A microelectronic microphone free-field sensitivity test device according to claim 1, characterized in that: The face shield plate layer is perforated with a hole diameter of 2mm~4mm and a perforation rate of 20%~25%; The thickness of the glass wool layer and the hollow layer is 40mm~60mm; The micro-perforated layer is perforated with a hole diameter of 1 mm and a perforation rate of 2.5% to 3.5%.

3. A microelectronic microphone free-field sensitivity test device according to claim 2, characterized in that: The aperture of the faceplate is 3 mm, and the perforation rate is 25%; The thickness of glass wool layer and hollow layer is 50mm; The pore size of the micro-perforated layer is 1 mm, and the perforation rate is 3%.

4. The microelectronic microphone free-field sensitivity test device according to claim 1, characterized in that: A coordinate system is established with the center of the upper surface of the muffler, with the long side of the muffler as the X-axis direction, the short side as the Y-axis direction, and the vertical direction as the Z-axis direction; The three-dimensional positioning device includes an X-axis translation mechanism, a Y-axis translation mechanism and a Z-axis translation mechanism, which are used to drive the mounting seat to move and position three-dimensionally in the muffler; The three-dimensional positioning device is provided with an emergency stop button.

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