Panel assembly of a microphone array and a sound wave imager

Abstract

The application provides a panel assembly of a microphone array and a sound wave imager. Based on the application, the array panel has a sound absorption structure arranged in a staggered manner with a sound pickup hole. When sound waves generated by a sound source propagate to the outer side surface of the array panel, a part of the sound waves passing through the sound pickup hole can be captured by the microphone, and at least a part of the remaining sound waves can be absorbed by the sound absorption structure of the array panel, so that the echo generated by the reflection of the remaining sound waves outside the sound pickup hole on the outer side surface of the array panel can be reduced, and the difference in echo energy interfering with different microphones in the microphone array is also reduced, thereby helping to improve the sound pickup consistency of the microphone array.

Description

Technical Field

[0001] This application relates to audio acquisition technology, and more particularly to a panel assembly for a microphone array and an acoustic imaging device using the panel assembly. Background Technology

[0002] Electronic devices can be equipped with microphone arrays. When sound waves generated by a sound source propagate to the electronic device, the sound waves within the pickup range of each microphone in the array can be captured by that microphone, enabling the electronic device to collect audio from the sound source. At the same time, another portion of the sound waves outside the pickup range of each microphone will be reflected by the electronic device. The echoes formed by these reflected sound waves will interfere with the pickup of each microphone.

[0003] Typically, the echo energy that interferes with different microphones in a microphone array varies, and this energy difference leads to different interference intensities for different microphones, resulting in poor sound pickup consistency of the microphone array.

[0004] Therefore, how to improve the sound pickup consistency of microphone arrays has become a technical problem that needs to be solved in the existing technology. Summary of the Invention

[0005] In view of this, embodiments of this application provide a panel assembly for a microphone array, which helps to improve the pickup consistency of the microphone array. The panel assembly for the microphone array may include an array panel, wherein:

[0006] The array panel has multiple pickup holes, each of which corresponds to the deployment position of a microphone in the microphone array, and each pickup hole is a through hole that penetrates the array panel.

[0007] The array panel also has a sound-absorbing structure that is staggered from the plurality of pickup holes.

[0008] In some examples, the sound-absorbing structure may optionally include: a plurality of sound-absorbing holes that are staggered from the plurality of pickup holes; and / or, a sound-absorbing panel layer that avoids the plurality of pickup holes on the outer side of the array panel facing away from the microphone array, the sound-absorbing panel layer comprising a porous material.

[0009] In some examples, each of the sound-absorbing holes is optionally a through-hole extending through the array panel; the panel assembly further includes a sound-absorbing medium layer disposed on the inner side of the array panel facing the microphone array, the sound-absorbing medium layer having medium clearance holes corresponding one-to-one with the plurality of pickup holes, and the sound-absorbing medium layer covering the plurality of sound-absorbing holes on the inner side of the array panel.

[0010] In some examples, the sound-absorbing medium layer may optionally comprise a porous material, and the porosity of the porous material in the sound-absorbing medium layer is greater than or equal to the porosity of the porous material in the sound-absorbing panel layer.

[0011] In some examples, optionally, the porosity of the porous materials of both the sound-absorbing panel layer and the sound-absorbing medium layer is between 65% and 75%.

[0012] In some examples, optionally, the porosity of at least one of the sound-absorbing panel layer and the sound-absorbing medium layer is 70%.

[0013] In some examples, the length of the sound-absorbing hole is optionally a preset multiple of the target wavelength of the sound wave.

[0014] In some examples, the length of the sound-absorbing aperture is optionally 1 / 4 of the target wavelength.

[0015] In some examples, the thickness of the sound-absorbing panel layer is optionally a preset multiple of the target wavelength of the sound wave.

[0016] In some examples, the thickness of the sound-absorbing panel layer is optionally 1 / 4 of the target wavelength.

[0017] In some examples, the thickness of the sound-absorbing medium layer may optionally be a preset multiple of the target wavelength of the sound wave.

[0018] In some examples, the thickness of the sound-absorbing medium layer is optionally 1 / 4 of the target wavelength.

[0019] In some examples, the aperture of the sound-absorbing hole is optionally smaller than or equal to the aperture of the sound-collecting hole.

[0020] In some examples, the pickup hole may optionally be an opening on the outer surface of the array panel facing away from the microphone array, with a conical hole wall.

[0021] Based on the above embodiments, the array panel has a sound-absorbing structure that is misaligned with the microphone aperture. When the sound waves generated by the sound source propagate to the outer surface of the array panel, a portion of the sound waves passing through the microphone aperture can be captured by the microphone, and at least a portion of the remaining sound waves can be absorbed by the sound-absorbing structure of the array panel. This reduces the amount of echo generated by the reflection of the remaining sound waves outside the microphone aperture on the outer surface of the array panel. Furthermore, the difference in echo energy that interferes with different microphones in the microphone array is also reduced. Consequently, this not only helps to reduce audio acquisition noise caused by sound wave echo interference, but also helps to improve the pickup consistency of the microphone array.

[0022] In another embodiment of this application, an acoustic imager is provided, which may include a microphone array and an array panel as described in the foregoing embodiments. In a direction perpendicular to the main body of the panel, the distance between each microphone in the microphone array and the corresponding pickup hole is equal. Thus, the imaging quality of the acoustic imager can be improved by enhancing the pickup consistency of the microphone array through the panel assembly. Attached Figure Description

[0023] The following figures are for illustrative purposes only and do not limit the scope of this application:

[0024] Figure 1 This is a partial structural cross-sectional view of the panel assembly of the microphone array in one embodiment of this application;

[0025] Figure 2 For the basis of Figure 1 The diagram shows the principle of acoustic wave reflection for the panel assembly.

[0026] Figure 3 For example Figure 1 A schematic diagram showing the sound absorption capacity of the sound-absorbing medium layer in the panel assembly.

[0027] Figure 4 For example Figure 1 A schematic diagram of the optimized structure of the panel assembly shown;

[0028] Figure 5 This is a schematic diagram of an exemplary partial structure of an electronic device in another embodiment of this application;

[0029] Figure 6 For example Figure 5 The electronic device applications in the illustrated embodiments are as follows: Figure 4 The diagram shows the optimized structure. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided with reference to the accompanying drawings and embodiments.

[0031] Figure 1 This is a partial structural cross-sectional view of the panel assembly of the microphone array in one embodiment of this application. Please refer to... Figure 1 In the embodiments of this application, the panel assembly of the microphone array may include an array panel 10, wherein the array panel 10 may have a plurality of pickup holes 110, the plurality of pickup holes 110 corresponding one-to-one with the deployment position of each microphone in the microphone array, and each pickup hole 100 is a through hole penetrating the array panel 10.

[0032] Specifically, in the embodiments of this application, the microphones of the microphone array can be deployed in a regular array configuration with row and column alignment. If so, the multiple pickup holes 110 can also be deployed in a regular array on the array panel 10 in a manner corresponding one-to-one with the deployment positions of each microphone. Although Figure 1 The diagram illustrates the distribution of multiple pickup holes 110 at equal intervals. However, the microphones in the microphone array can also be deployed in an irregular array pattern, free from the constraints of row and column alignment. In this case, the multiple pickup holes 110 deployed in a manner that corresponds one-to-one with the deployment positions of each microphone can also be presented in an irregular array pattern on the array panel 10, consistent with the microphone array. That is, the spacing between adjacent microphones and the spacing between corresponding adjacent pickup holes 110 may not be the same, and each microphone and its corresponding adjacent 110 can be distributed according to any rule other than row and column alignment.

[0033] In other words, the embodiments of this application do not intend to impose unnecessary restrictions on the distribution of the multiple pickup holes 110, as long as the condition that the multiple pickup holes 110 correspond one-to-one with the deployment position of each microphone in the microphone array is met.

[0034] In embodiments of this application, the array panel 10 further includes a sound-absorbing structure offset from the plurality of pickup holes 110. This sound-absorbing structure absorbs sound waves that do not pass through the pickup holes 110, thereby reducing echoes generated by reflections of these residual sound waves on the outer surface of the array panel 10. Specifically, the offset distribution of the sound-absorbing structure from the plurality of pickup holes 110 means that the sound-absorbing structure is distributed on the array panel 10 in a manner that avoids any arbitrary regularity of the plurality of pickup holes 110.

[0035] Based on the above embodiments, since the array panel 10 has a sound-absorbing structure that is misaligned with the pickup hole 110, when the sound wave generated by the sound source propagates to the outer surface of the array panel 10, a portion of the sound wave passing through the pickup hole 110 can be captured by the microphone, and at least a portion of the remaining sound wave can be absorbed by the sound-absorbing structure of the array panel 10.

[0036] In the embodiments of this application, the sound-absorbing structure can be any structure with sound wave absorption capability.

[0037] For example, in Figure 1 In this example, the sound-absorbing structure includes multiple sound-absorbing holes 120 that are staggered from the multiple pickup holes 110. Specifically, the array panel 10 can also have multiple sound-absorbing holes 120, which are staggered from the multiple pickup holes 110. At least a portion of the sound waves that do not pass through the pickup holes 110 can enter the sound-absorbing holes 120 and attenuate or even disappear within them. Specifically, the staggered distribution of the multiple sound-absorbing holes 120 (i.e., the sound-absorbing structure) from the multiple pickup holes 110 means that the multiple sound-absorbing holes 120 (i.e., the sound-absorbing structure) are positioned in the array panel 10 to avoid the multiple pickup holes 110. Figure 1 The diagram illustrates a sound-absorbing hole 120 (i.e., a sound-absorbing structure) distributed at the midpoint between adjacent pickup holes 110. However, the sound-absorbing holes 120 (i.e., the sound-absorbing structure) may not be distributed in a staggered manner at the midpoint between every two pickup holes 110, but may be distributed on the array panel 10 in any rule that avoids the pickup holes 110.

[0038] For example, the sound-absorbing structure may not include the sound-absorbing holes 120, but only include a sound-absorbing panel layer on the outer side of the array panel 10 facing away from the microphone array, avoiding multiple pickup holes 110. This sound-absorbing panel layer may include porous materials, such as polyester fibers like PET (Polyethylene terephthalate). Specifically, the sound-absorbing panel layer can be deployed in the area on the outer side of the array panel 10 facing away from the microphone array where no pickup holes 110 are provided. Furthermore, this sound-absorbing panel layer may be an independent additional structure attached to the outer side of the array panel 10, or it may be an integrally integrated partial structure of the array panel 10. If the sound-absorbing panel layer is integrally integrated into the partial structure of the array panel 10, then the array panel 10 can be made entirely of porous materials.

[0039] For example, as a solution with optimal sound absorption effect, the sound-absorbing structure can also simultaneously include... Figure 1 The sound-absorbing holes 120 and the aforementioned sound-absorbing plate layer are shown in the figure.

[0040] When the sound-absorbing structure includes sound-absorbing holes 120, in order to improve the sound absorption capability of the panel assembly, each sound-absorbing hole 120 can be configured as a through hole penetrating the array panel 10. Furthermore, the panel assembly can also include a sound-absorbing medium layer 20, which is deployed on the inner side of the array panel 10 facing the microphone array. For example, the sound-absorbing medium layer 20 can be stacked on the inner surface of the array panel 10 facing the microphone array. The sound-absorbing medium layer 20 has medium clearance holes 210 that correspond one-to-one with the plurality of pickup holes 110. Moreover, the sound-absorbing medium layer 20 can cover all the plurality of sound-absorbing holes 120 on the inner side of the array panel 10 facing the microphone array.

[0041] In the embodiments of this application, the sound-absorbing medium layer 20 may also be made of a porous material. The porous material of the sound-absorbing plate layer mentioned above and the porous material of the sound-absorbing medium layer 20 mentioned here may be the same or different. For example, the porous material of the sound-absorbing medium layer 20 may be ultrafine glass wool. Glass wool is a cotton-like material formed by fiberizing molten glass, and ultrafine glass wool is a planar material with a fiber diameter less than or equal to 2 μm obtained after deep processing of glass wool.

[0042] To distinguish between the porous material of the sound-absorbing panel layer and the porous material of the sound-absorbing medium layer 20 included in the sound-absorbing structure, the porous material of the sound-absorbing panel layer will be referred to as the first porous material and the porous material of the sound-absorbing medium layer 20 will be referred to as the second porous material.

[0043] Figure 2 For the basis of Figure 1 The diagram shows the principle of sound wave reflection for the panel assembly. Figure 2 In this diagram, Pi represents the incident sound wave generated by the sound source, Pt represents the transmitted sound wave that passes through the pickup hole 110 and is captured by the microphone, Pr represents the echo formed by reflection at the outer surface of the array panel 10, Ra represents the acoustic resistance of the air as the sound wave propagation medium, and Rb represents the acoustic resistance of the array panel 10. The incident sound wave Pi generated by the sound source is typically a spherical wave. Since the array panel 10 is flat in this embodiment, the incident sound wave Pi reaching the outer surface of the array panel 10 can also be considered a plane wave. Figure 2 The acoustic wave reflection model shown is based on the condition that the incident acoustic wave Pi is considered as a plane wave.

[0044] from Figure 2As can be seen from this, since Rb>Ra, the outer surface of the array panel 10 serves as the medium boundary between the air and the array panel 10. It is a "hard" boundary where acoustic impedance changes during sound wave propagation. The particle velocity phase difference between the echo Pr generated by the reflection of the "hard" boundary and the incident sound wave Pi is 180°. The sound pressure phase between the echo Pr generated by the reflection of the "hard" boundary and the incident sound wave Pi is the same. As a result, the energy of the echo Pr formed after reflection is relatively strong.

[0045] Based on the above-described structure of the embodiments of this application, at least a portion of the residual sound waves located outside the pickup hole 110 (i.e., outside the pickup range of the microphone) can be absorbed by the sound-absorbing structure of the array panel 10 (e.g., sound-absorbing plate layer and / or sound-absorbing hole 120). Therefore, the sound-absorbing structure of the array panel 10 can reduce the hardness of the "hard" boundary. Moreover, in the preferred embodiment where the sound-absorbing hole 120 is configured as a through hole and the panel assembly also includes a sound-absorbing medium layer 20, a portion of the residual sound waves can further pass through the sound-absorbing hole 120 and be absorbed by the sound-absorbing medium layer 20 deployed on the inner side of the panel of the array panel 10. That is, the porous material included in the array panel 10 and the sound-absorbing medium layer 20 covering the sound-absorbing hole 120 opened in the array panel 10 can further reduce the hardness of the "hard" boundary.

[0046] Therefore, the embodiments of this application can reduce the amount of echo generated by the reflection of residual sound waves outside the pickup hole on the outer surface of the array panel 10 based on the sound-absorbing structure of the array panel 10. Furthermore, the difference in echo energy that interferes with different microphones in the microphone array will also be reduced. In this way, it helps to reduce audio acquisition noise caused by sound wave echo interference and also helps to improve the pickup consistency of the microphone array.

[0047] In a preferred embodiment where the sound-absorbing structure includes a sound-absorbing hole 120 configured as a through hole and the panel assembly also includes a sound-absorbing medium layer 20, the sound-absorbing hole 120, in addition to serving as a propagation channel for the incident sound wave Pi to penetrate the array panel 10 and reach the sound-absorbing medium layer 20, can also have sound-absorbing capabilities itself. Therefore, the sound-absorbing hole 120 should not be configured to have an excessively large aperture to avoid the cavity of the sound-absorbing hole 120 becoming an open cavity that cannot be absorbed by sound wave oscillations. Accordingly, the aperture of the sound-absorbing hole 120 can be smaller than or equal to the aperture of the pickup hole 110.

[0048] To further optimize the sound absorption capability of the microphone array panel assembly and achieve the highest possible sound pickup consistency of the microphone array, the above-described preferred embodiment of this application can optimize the material parameters of the sound-absorbing plate layer, the material parameters of the sound-absorbing medium layer 20, the size parameters of the sound-absorbing holes 120, and the size parameters of the array panel 10 and the sound-absorbing medium layer 20, which will be described in detail below.

[0049] (1) The material parameters of the sound-absorbing panel layer and the material parameters of the sound-absorbing medium layer 20 that may be included in the sound-absorbing structure of the array panel 10.

[0050] If the sound-absorbing structure of the array panel 10 includes a sound-absorbing plate layer made of a first porous material, then the material parameters of the sound-absorbing plate layer that the sound-absorbing structure of the array panel 10 may include the porosity of the first porous material of the sound-absorbing plate layer.

[0051] If the panel assembly further includes a sound-absorbing medium layer 20 made of a second porous material, then the material parameters of the sound-absorbing medium layer 20 may include the porosity of the second porous material of the sound-absorbing medium layer 20.

[0052] Porosity refers to the percentage of the volume of pores inside the material (i.e., the first porous material and the second porous material) to the total volume of the material (i.e., the first porous material and the second porous material), and porosity is related to pore size.

[0053] The larger the pore size, the smaller the flow resistance of air in the porous material (i.e., the first porous material and the second porous material), and vice versa. The flow resistance Rf of air in the porous materials (i.e., the first porous material and the second porous material) can be considered as: under the stable airflow state in the environment where the panel assembly is located, the ratio of the pressure gradient ∆P inside the porous materials (i.e., the first porous material and the second porous material) to the airflow linear velocity U inside the porous materials (i.e., the first porous material and the second porous material) is Rf=∆P / U. The pressure gradient ∆P refers to the pressure change per unit path length along the fluid flow direction of the air in the array panel 10 or the sound-absorbing medium layer 20 (e.g., the thickness direction of the porous materials (i.e., the first porous material and the second porous material)). The airflow linear velocity U refers to the speed of air movement in the fluid flow direction (e.g., the thickness direction of the porous materials (i.e., the first porous material and the second porous material)) in the array panel 10 or the sound-absorbing medium layer 20.

[0054] Therefore, the greater the porosity (e.g., the larger the pore size), the lower the density of the porous material (i.e., the first porous material and the second porous material), and the lower the flow resistance of air in the porous material (i.e., the first porous material and the second porous material); conversely, the smaller the porosity, the greater the density of the porous material (i.e., the first porous material and the second porous material), and the greater the flow resistance of air in the porous material (i.e., the first porous material and the second porous material).

[0055] If the flow resistance of air in the porous material (i.e., the first porous material and the second porous material) is too small, then the friction and viscosity of the porous material (i.e., the first porous material and the second porous material) on the air are limited. The energy loss of the sound wave with air as the propagation medium in the porous material (i.e., the first porous material and the second porous material) is low, resulting in a weak sound absorption capacity of the porous material (i.e., the first porous material and the second porous material) for the incident sound wave Pi.

[0056] If the flow resistance of air in the porous material (i.e., the first porous material and the second porous material) is too high, the air's ability to penetrate the porous material (i.e., the first porous material and the second porous material) is weak, resulting in the porous material (i.e., the first porous material and the second porous material) having a weaker ability to absorb incident sound waves Pi.

[0057] Furthermore, experiments have shown that the sound absorption capacity of porous materials (i.e., the first porous material and the second porous material) for incident sound wave Pi is related not only to porosity but also to the frequency of the incident sound wave Pi. That is, at the same thickness:

[0058] The lower the porosity, the higher the density of the porous material (i.e., the first porous material and the second porous material), the better the sound absorption ability of the porous material (i.e., the first porous material and the second porous material) for sound waves in the low-to-mid frequency range of the incident sound wave Pi.

[0059] Conversely, the higher the porosity, that is, the lower the density of the porous material (i.e., the first porous material and the second porous material), the better the sound absorption ability of the porous material (i.e., the first porous material and the second porous material) for sound waves in the high-frequency range of the incident sound wave Pi.

[0060] Therefore, in setting a reasonable porosity for the porous materials (i.e., the first porous material and the second porous material), the embodiments of this application can consider the frequency band of the sound wave that is expected to be absorbed more in the incident sound wave Pi. That is, the porosity of the porous materials (i.e., the first porous material and the second porous material) is inversely proportional to the target frequency of the sound wave, which refers to the frequency band of the sound wave that is expected to be absorbed more in the incident sound wave Pi.

[0061] For example, the frequency band of the sound wave that is expected to be absorbed more can be a high frequency band greater than or equal to 30KHz. In this case, the porosity of the porous material (i.e., the first porous material and the second porous material) can be between 65% and 75%, and more preferably, the porosity of at least one of the first porous material and the second porous material can be 70%.

[0062] In addition, considering that the array panel 10 is the outer cover of the microphone array, the sound-absorbing plate layer on its outer side needs to have a certain strength. Therefore, the density of the first porous material can be slightly higher than that of the second porous material, that is, the porosity of the second porous material is greater than or equal to that of the first porous material.

[0063] That is, in a preferred embodiment where the sound-absorbing structure includes both a sound-absorbing panel and a sound-absorbing hole 120 configured as a through hole, and the panel assembly also includes a sound-absorbing medium layer 20, the sound-absorbing panel located on the outer side of the array panel 10 can both absorb sound and protect the microphone array, while the sound-absorbing medium layer 20 can utilize the sound-absorbing hole 120 configured as a through hole to absorb more sound.

[0064] (2) Dimensions of sound-absorbing hole 120

[0065] In a preferred embodiment where the sound-absorbing structure includes at least a sound-absorbing hole 120 configured as a through hole and the panel assembly further includes a sound-absorbing medium layer 20, the dimensional parameters of the sound-absorbing hole 120 may include the hole length of the sound-absorbing hole 120. If the array panel 10 is a flat plate with uniform thickness, then the hole length of the sound-absorbing hole 120 may be equal to the thickness of the array panel 10.

[0066] As mentioned earlier, the sound-absorbing hole 120, besides serving as a propagation channel for the incident sound wave Pi to penetrate the array panel 10 and reach the sound-absorbing medium layer 20, can also possess sound-absorbing capabilities itself. Therefore, if the sound-absorbing hole 120 has a suitable hole length, its own sound-absorbing capability can be maximized. Specifically, the portion of the incident sound wave Pi with the target wavelength can be absorbed by the porous material of the array panel 10 where the sound-absorbing hole 120 is located through oscillation within the sound-absorbing hole 120 with a suitable hole length. The target wavelength can be the quotient of the speed of sound propagation in air and the target frequency mentioned earlier.

[0067] Therefore, in the embodiments of this application, in order to make the portion of the incident sound wave Pi with the target wavelength absorbed by the sound-absorbing hole 120, the length of the sound-absorbing hole 120 can be set to be proportional to the target wavelength λ of the sound wave or inversely proportional to the target frequency of the sound wave.

[0068] The length of the sound-absorbing hole 120 is proportional to the target wavelength of the sound wave. It can be simplified as the length of the sound-absorbing hole being a preset multiple of the target wavelength, that is, the length of the sound-absorbing hole 120 is L=p×λ. For example, the preset multiple p can be 1 / 4.

[0069] (3) The sound-absorbing structure of the array panel 10 may include the size parameters of the sound-absorbing panel layer and the size parameters of the sound-absorbing medium layer 20.

[0070] The aforementioned sound-absorbing structure of the array panel 10 may include the dimensional parameters of the sound-absorbing panel layer and the dimensional parameters of the sound-absorbing medium layer 20, which may include the thickness of the sound-absorbing panel layer and the sound-absorbing medium layer 20. If the sound-absorbing panel layer is integrally integrated into the local structure of the array panel 10 and the array panel 10 as a whole is made of porous material, then the maximum thickness of the sound-absorbing panel layer can be equal to the thickness of the array panel 10.

[0071] The following description uses the maximum value of the thickness of the sound-absorbing panel layer being equal to the thickness of the array panel 10 as an example. That is, the array panel 10 is made of porous material as a whole, and the sound-absorbing structure of the array panel 10 may include the thickness of the sound-absorbing panel layer.

[0072] Figure 3 For example Figure 1 This diagram illustrates the sound absorption capacity of the sound-absorbing medium layer in the panel assembly. Figure 3 The diagram shows three curves (S31-S33) showing the relationship between the sound absorption coefficient α of the same sound-absorbing material and different frequencies (f) when different thicknesses are selected. Curve S31 corresponds to a material thickness of 100mm, curve S32 to a material thickness of 50mm, and curve S33 to a material thickness of 25mm. Furthermore, from... Figure 3 It can be seen from this:

[0073] For any sound-absorbing material, for every doubling of the material thickness, the frequency band corresponding to the optimal sound absorption coefficient shifts to a lower frequency range by one octave.

[0074] Increasing the material thickness can improve its sound absorption coefficient for low-frequency sound waves; and,

[0075] The absorption coefficient of the material for high-frequency sound waves is not significantly affected by the increase in material thickness.

[0076] Therefore, in the embodiments of this application, the thickness of the array panel 10 (i.e., the thickness of the sound-absorbing plate layer) and the thickness of the sound-absorbing medium layer 20 can be set according to the target frequency or target wavelength λ of the sound wave. That is, the thickness of the array panel 10 (i.e., the thickness of the sound-absorbing plate layer) and the thickness of the sound-absorbing medium layer 20 can be set to be proportional to the target wavelength λ of the sound wave or inversely proportional to the target frequency of the sound wave. Wherein, the thickness of the array panel 10 (i.e., the thickness of the sound-absorbing plate layer) and the thickness of the sound-absorbing medium layer 20 being proportional to the target wavelength of the sound wave can be simplified as follows: the thickness of the array panel 10 (i.e., the thickness of the sound-absorbing plate layer) and the thickness of the sound-absorbing medium layer 20 are both preset multiples of the target wavelength.

[0077] As mentioned earlier, if the array panel 10 is a flat plate with uniform thickness, then the length of the sound-absorbing hole 120 can be equal to the thickness of the array panel 10 (e.g., the thickness of the sound-absorbing layer). Therefore, the thickness of the array panel 10 (e.g., the thickness of the sound-absorbing layer) can be calculated using the formula p×λ for the length L of the sound-absorbing hole 120 mentioned earlier. Similarly, the thickness T of the sound-absorbing medium layer 20 is T=q×λ.

[0078] Experiments have shown that if the thickness of the array panel 10 (i.e. the thickness of the sound-absorbing plate layer) and the thickness of the sound-absorbing medium layer 20 are set to 1 / 4 of any wavelength, then the sound-absorbing plate layer and the sound-absorbing medium layer 20 can achieve the optimal sound absorption coefficient for sound waves with that wavelength. Therefore, preferably, the preset multiple q can be 1 / 4.

[0079] For example, if the target frequency is 40kHz, then the target wavelength λ is 340 / (40×1000) = 8.5mm, and the thickness T of the sound-absorbing plate layer and the sound-absorbing medium layer 20 to achieve the optimal sound absorption coefficient for sound waves with the target wavelength λ can be 1 / 4×λ≈2.13mm.

[0080] For example, if the target frequency band is 30KHz, then the target wavelength λ is 340 / (40×1000)≈11.33mm, and the thickness T of the sound-absorbing plate layer and the sound-absorbing medium layer 20 to achieve the best sound absorption coefficient for the sound wave with the target wavelength λ can be 1 / 4×λ≈2.83mm.

[0081] In addition to reducing noise, in the embodiments of this application, the signal-to-noise ratio of audio acquisition can also be improved by increasing the energy of the incident sound wave Pi captured by the microphone.

[0082] Figure 4 For example Figure 1 The diagram shows an optimized structure of the panel assembly. Please refer to [link / reference]. Figure 4 In embodiments of this application, the opening of the pickup hole 110 on the outer surface of the array panel 10 can be an opening 115 with a conical cavity wall. This opening 125 is used to guide and converge more incident sound waves Pi into the pickup hole 110, so that more incident sound waves Pi can propagate through the pickup hole 110 to their corresponding microphone. For example, the conical cavity wall of the opening 115 can have a tilt angle of 30° to 35° relative to the sound transmission direction perpendicular to the array panel 10. Preferably, the tilt angle can be 33°.

[0083] Figure 5 This is an exemplary partial structural diagram of an electronic device in another embodiment of this application. Figure 6 For example Figure 5 The electronic device applications in the illustrated embodiments are as follows: Figure 4 The diagram shows the optimized structure. Please refer to [link / reference]. Figure 5 and Figure 6 In another embodiment of this application, an electronic device such as an acoustic imaging device may include a microphone array 30 and the panel assembly described in the foregoing embodiments. Figure 5 and Figure 6 Only a portion of the microphones 300 in the microphone array 30 and their corresponding pickup holes 110 and clearance holes 210 are shown in the image, but it is understood that the number of microphones 300 included in the microphone array 30 may not be limited to this.

[0084] Furthermore, in the embodiments of this application, in order to ensure the consistency of sound pickup of the microphone array 30, the distance between each microphone 300 in the microphone array 30 and the corresponding pickup hole 110 is equal in the direction perpendicular to the array panel 10.

[0085] The microphone array 30 may include a rigid array substrate 310, such as a PCB (Printed Circuit Board), which may be parallel to the array panel 10. For example, in the case where the panel assembly in the foregoing embodiment includes a sound-absorbing medium layer 20, the array substrate 310 may be stacked on the sound-absorbing medium layer 20 in an orientation parallel to the array panel 10. Furthermore, the array substrate 310 also has a corresponding substrate through-hole 3100 at the deployment location of each microphone 300, and each microphone 300 covers the corresponding substrate through-hole 3100 on the substrate surface of the array substrate 310 facing away from the sound-absorbing medium layer 20. Thus, each microphone 300 may have a sound transmission channel passing through the corresponding pickup hole 110, the corresponding clearance hole 210, and the corresponding substrate through-hole 3100. Moreover, the array substrate 310 may be stacked on the sound-absorbing medium layer 20 in an orientation parallel to the array panel 10, so that the length of each microphone 300 and the distance between its corresponding pickup hole 110 are the same.

[0086] It is understood that, although not shown in the figures, the electronic device in the embodiments of this application may also include at least one of processors such as CPU (central processing unit), MCU (microcontroller unit), FPGA (field-programmable gate array) for acquiring and processing audio data generated by microphone 300 based on captured transmitted sound wave Pt.

[0087] In some examples of embodiments of this application, such as Figure 5 or Figure 6The electronic device shown can be an acoustic imager. An acoustic imager can be based on microphone array measurement technology, measuring the phase difference of sound waves arriving at each microphone within a certain space, determining the location of the sound source according to the phased array principle, measuring the amplitude of the sound source, and displaying the spatial distribution of the sound source as an image. In this case, the processor of the acoustic imager can be configured as follows:

[0088] Acquire audio signals detected by the microphone array;

[0089] The location of the sound source and the amplitude of the sound wave are determined based on the phase difference between the audio signals of each microphone.

[0090] Based on the determined sound source location and sound wave amplitude, a sound wave image is generated. The pixel value of each pixel in the sound wave image is used to characterize the sound wave amplitude distribution within the array area of ​​the microphone array. Furthermore, the pixel value of each pixel in the sound wave image decreases in a gradient with respect to the sound source location.

[0091] Since the panel assembly in the aforementioned embodiments can reduce audio acquisition noise caused by echo interference of sound waves and simultaneously improve the pickup consistency of the microphone array, the signal quality of the audio signal acquired by the acoustic imager including the panel assembly can be improved. This improves the accuracy of the sound source location and sound wave amplitude determined based on the signal phase difference, and further improves the image quality of the acoustic image.

[0092] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A panel assembly for a microphone array, characterized in that, The panel assembly includes an array panel and a sound-absorbing medium layer, wherein: The array panel has multiple pickup holes, each of which corresponds to the deployment position of a microphone in the microphone array, and each pickup hole is a through hole that penetrates the array panel. The sound-absorbing medium layer is stacked on the inner side of the array panel facing the microphone array, and the sound-absorbing medium layer has medium clearance holes corresponding to the plurality of pickup holes one by one; The array panel also has a sound-absorbing structure that is staggered from the plurality of pickup holes; The sound-absorbing structure includes a plurality of sound-absorbing holes that are staggered with the plurality of pickup holes. Each of the sound-absorbing holes is a through hole that penetrates the array panel. Furthermore, the sound-absorbing medium layer covers the plurality of sound-absorbing holes on the inner side of the array panel.

2. The panel assembly according to claim 1, characterized in that, The sound-absorbing structure also includes: A sound-absorbing panel layer that avoids the multiple pickup holes is located on the outer side of the array panel facing away from the microphone array.

3. The panel assembly according to claim 2, characterized in that, The sound-absorbing medium layer comprises a porous material, and the sound-absorbing panel layer comprises a porous material.

4. The panel assembly according to claim 3, characterized in that, The porosity of the porous material in the sound-absorbing medium layer is greater than or equal to the porosity of the porous material in the sound-absorbing plate layer.

5. The panel assembly according to claim 4, characterized in that, The porosity of the porous materials in the sound-absorbing panel layer and the sound-absorbing medium layer is between 65% and 75%.

6. The panel assembly according to claim 5, characterized in that, The porosity of at least one of the porous materials in the sound-absorbing panel layer and the sound-absorbing medium layer is 70%.

7. The panel assembly according to claim 3, characterized in that, The length of the sound-absorbing hole, and / or the thickness of the sound-absorbing plate layer, and / or the thickness of the sound-absorbing medium layer, are preset multiples of the target wavelength of the sound wave.

8. The panel assembly according to claim 7, characterized in that, The length of the sound-absorbing hole, and / or the thickness of the sound-absorbing plate layer, and / or the thickness of the sound-absorbing medium layer, is 1 / 4 of the target wavelength.

9. The panel assembly according to claim 1, characterized in that, The diameter of the sound-absorbing hole is smaller than or equal to the diameter of the sound-collecting hole.

10. An acoustic imaging device, characterized in that, It includes a microphone array and a panel assembly as described in any one of claims 1 to 9, wherein, in a direction perpendicular to the array panel, the distance between each microphone in the microphone array and the corresponding pickup hole is equal.

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