High-frequency enhanced bone conduction microphone and bone conduction sound transmission method

Abstract

A high-frequency enhanced bone conduction microphone and a bone conduction sound transmission method. The bone conduction microphone includes a housing, and an ASIC chip, a diaphragm, and a MEMS microphone disposed inside the housing. The bone conduction microphone further includes a perforated plate. The diaphragm is disposed in the middle of the bone conduction microphone, and the perforated plate is installed below the diaphragm. The diaphragm and the perforated plate divide the housing space into three regions. Among them, the space above the diaphragm forms the front cavity of the bone conduction microphone, the space below the perforated plate forms the back cavity, and the space between the diaphragm and the perforated plate forms an air gap. The ASIC chip and the MEMS microphone are disposed above the diaphragm, and a first sound hole is opened on the surface of the MEMS microphone. An opening is provided on the diaphragm directly below the MEMS microphone, so that the back surface of the MEMS microphone is connected to the air gap. A second sound hole is opened on the perforated plate. The high-frequency enhanced bone conduction microphone of the present invention forms a resonance peak with a resonance frequency in the high frequency through cavity structures such as the front cavity and the air gap, and realizes the enhancement effect of the high-frequency frequency response.

Description

Technical Field

[0001] The present invention belongs to the field of bone conduction sound transmission, and more specifically, relates to a bone conduction microphone with enhanced high frequency and a bone conduction sound transmission method. Background Art

[0002] A bone conduction microphone is a microphone that detects vibration signals caused by the vibration of the human vocal cords and transmitted to the skull. Compared with an air conduction microphone, a bone conduction microphone has the advantages of strong anti-interference ability, flexible wearing position, and stable working performance. At present, bone conduction microphones have been widely used in civilian and military fields. However, in the actual use process, there are two deficiencies in bone conduction microphones. First, since bone conduction noise is mostly concentrated in the low-frequency part below 100 Hz, the bone conduction microphone is prone to overload due to picking up too much low-frequency noise. Second, in the range of 5 kHz to 16 kHz, bone conduction speech naturally has the characteristic of excessive high-frequency attenuation, and the high-frequency frequency response of the bone conduction microphone lacks enhancement in this frequency band, so the clarity of the picked-up bone conduction speech is insufficient. Among them, the attenuation of the high-frequency frequency response greatly affects the sound pickup quality of the bone conduction microphone.

[0003] In the related art, CN211240080U also discloses a MEMS vibration sensor, which can be used as a bone conduction microphone. However, this MEMS (Mirco Electro Mechanical Systems) vibration sensor cannot solve the problem of excessive high-frequency frequency response attenuation.

[0004] The bone conduction microphone proposed by the present invention has acoustic structures such as sound holes and cavities inside, forming a new resonance peak in the high-frequency part of the frequency response of the bone conduction microphone, achieving the effect of enhancing the high-frequency frequency response and solving the deficiencies of this MEMS vibration sensor. Summary of the Invention

[0005] To solve the problem of excessive high-frequency attenuation of bone conduction speech in the prior art, the present invention proposes a bone conduction microphone with enhanced high frequency.

[0006] To achieve the above invention purpose, the present invention specifically adopts the following technical solutions.

[0007] A bone conduction microphone with enhanced high frequency, comprising a housing, and an ASIC chip, a diaphragm, and a MEMS microphone disposed inside the housing; characterized in that:

[0008] The bone conduction microphone further comprises a perforated plate, the diaphragm is disposed in the middle of the bone conduction microphone, the perforated plate is installed below the diaphragm, and the diaphragm and the perforated plate divide the housing space into three regions. Among them, the space above the diaphragm constitutes the front cavity of the bone conduction microphone, the space below the perforated plate constitutes the back cavity, and the space between the diaphragm and the perforated plate constitutes the air gap;

[0009] The ASIC chip and the MEMS microphone are placed above the diaphragm, and a first sound hole is formed on the surface of the MEMS microphone; an opening is provided on the diaphragm directly below the MEMS microphone, so that the back of the MEMS microphone communicates with the air gap; a second sound hole is formed on the perforated plate.

[0010] The present invention further includes the following preferred solutions.

[0011] The diaphragm is made of an elastic polymer.

[0012] A mass is installed below the diaphragm, and the diaphragm and the mass form a spring-mass oscillator structure.

[0013] The mass is made of a metal material.

[0014] When the mass is located below the opening of the diaphragm, an opening needs to be provided at the corresponding position of the mass to prevent the mass from blocking the opening of the diaphragm.

[0015] The diameter of the first sound hole is less than 10 μm.

[0016] As the aperture of the first sound hole becomes larger, the low-frequency attenuation of the high-frequency enhanced bone conduction microphone is more sufficient.

[0017] When the number of the second sound holes formed on the perforated plate is multiple, the second sound holes are uniformly distributed on the perforated plate, and the second sound holes are used to attenuate the amplitude of the mechanical resonance peak of the output signal.

[0018] The present application also discloses a sound transmission method using the aforementioned high-frequency enhanced bone conduction microphone at the same time, which is characterized by including the following steps:

[0019] Step 1, the bone conduction microphone receives a vibration signal, so that the diaphragm vibrates under excitation;

[0020] Step 2, after the diaphragm vibrates, a sound pressure change is formed under the combined action of the front cavity and the air gap;

[0021] Step 3, the MEMS microphone acquires the sound pressure change and converts it into an electrical signal;

[0022] Step 4, the ASIC chip processes the electrical signal and outputs a high-frequency enhanced sound signal.

[0023] Compared with the prior art, the present invention has the following beneficial technical effects:

[0024] (1) The present invention realizes the enhancement of the high-frequency frequency response of the bone conduction microphone and improves the clarity of picking up bone conduction voices.

[0025] (2) The present invention achieves low-frequency attenuation and resonance peak attenuation of the bone conduction microphone, avoiding the overload of the bone conduction microphone due to picking up too much low-frequency noise. It has a guiding role in the structural design and sound pickup optimization of future bone conduction microphones.

[0026] (3) The structure of the present invention is unique, with small size and light weight, and can be applied to a variety of working scenarios. Description of the Drawings

[0027] Figure 1 It is a cross-sectional view of a bone conduction microphone with high-frequency enhancement according to the present disclosure.

[0028] Figure 2 It is a force-acoustic analogy circuit diagram of a bone conduction microphone with high-frequency enhancement according to the present disclosure.

[0029] Figure 3 It is a schematic diagram of the frequency response curve of a bone conduction microphone with high-frequency enhancement according to the present disclosure.

[0030] Figure 4 It is the result diagram of the influence of the aperture r of the first sound hole on the MEMS microphone p on the low-frequency response of the bone conduction microphone with high-frequency enhancement.

[0031] Figure 1 In the figure: 11, front cavity; 12, air gap; 13, back cavity; 21, ASIC chip; 22, diaphragm; 23, first sound hole; 24, MEMS microphone; 25, mass block; 31, perforated plate; 32, second sound hole. Detailed Embodiments

[0032] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in this application are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the spirit of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

[0033] The present invention provides a novel structural design method for a bone conduction microphone to enable the bone conduction microphone to obtain an enhanced high-frequency frequency response, thereby improving the sound pickup quality of the bone conduction microphone.

[0034] The cross-sectional view of the bone conduction microphone with high-frequency enhancement is as Figure 1As shown in the figure. The high-frequency enhanced bone conduction microphone includes a housing, and an ASIC chip 21, a diaphragm 22, a MEMS microphone 24, and a perforated plate 31 disposed inside the housing. The diaphragm 22 is provided in the middle of the bone conduction microphone, and the perforated plate 31 is installed below the diaphragm 22. The diaphragm 22 and the perforated plate 31 divide the housing space into three regions. Among them, the space above the diaphragm 22 constitutes the front cavity 11 of the bone conduction microphone, the space below the perforated plate 31 and the inside of the bone conduction microphone housing constitutes the back cavity 13, and the space between the diaphragm 22 and the perforated plate 31 constitutes the air gap 12.

[0035] The diaphragm 22 is provided in the middle of the bone conduction microphone and is made of a polymer, having a certain elasticity. The ASIC (Application Specific Integrated Circuit) chip 21 and the MEMS microphone 24 are placed above the diaphragm 22. A first sound hole 23 with a diameter less than 10 μm is provided on the surface of the MEMS microphone 24 to attenuate the low-frequency frequency response, and the attenuation degree is related to the aperture. An opening is provided on the diaphragm 22 directly below the MEMS microphone 24, so that the back surface of the MEMS microphone 24 is connected to the air gap 12.

[0036] Further, a second sound hole 32 is provided on the perforated plate 31, and the number of openings is greater than 1, and the opening positions should be evenly distributed on the perforated plate 31. The second sound hole 32 can attenuate the amplitude of the mechanical resonance peak of the output signal, and the attenuation degree is related to the plate thickness, aperture, and perforation rate of the perforated plate. Further, a mass block 25 is installed below the diaphragm 22 as an additional mass, and the material is generally selected as metal. The diaphragm 22 and the mass block 25 form a spring oscillator structure, and its mechanical resonance frequency is related to the compliance of the diaphragm 22 and the mass of the mass block 25.

[0037] When a person makes a sound, the vibration signal generated by the vocal cords is transmitted to the skull and received by the bone conduction microphone. The diaphragm 22 of the bone conduction microphone vibrates under excitation, causing a changing sound pressure signal to be generated inside the bone conduction microphone. The mass block 25 below the diaphragm 22 serves as an additional mass of the diaphragm 22. The MEMS microphone 24 detects the difference in the sound pressure changes inside the front cavity 11 and the air gap 12, converts it into an electrical signal, and outputs it after being processed by the ASIC chip 21, which is the output signal of the high-frequency enhanced bone conduction microphone. The first sound hole 23 and the second sound hole 32 play a role in adjusting the frequency response of the output signal.

[0038] Through Figure 2 Analysis of the force-sound analogy circuit diagram of the high-frequency enhanced bone conduction microphone shows that the first sound hole 23 provides an equivalent acoustic impedance R AP +M AP , causing the frequency response curve of the bone conduction microphone to attenuate at a rate of 6 dB / Oct in the low frequency. When the volume of the front cavity 11 is constant, the low-frequency attenuation frequency range is only related to the aperture of the first sound hole 23, as shown inFigure 4 The mass M of the diaphragm 22 MD and the compliance C MS form a mechanical resonance peak in the frequency response curve during resonance. The second sound holes 32 on the perforated plate 31 provide an equivalent acoustic impedance R AS +M AS , where the equivalent acoustic resistance R AS can attenuate the amplitude of the mechanical resonance peak, and the larger the value of R AS , the more obvious the attenuation. The equivalent acoustic capacitance C of the front cavity 11 AF and the equivalent acoustic capacitance C of the air gap 12 AG are in series, and together with the equivalent acoustic mass M of the diaphragm 22 AD = M MD / S 2 form a new resonance peak in the high-frequency part of the frequency response curve, and its amplitude is affected by the equivalent acoustic resistance R of the air gap 12 AG , thereby achieving the effect of enhancing the high-frequency frequency response. Based on the above analysis, the frequency response curve of the bone conduction microphone with high-frequency enhancement can be obtained, as shown in Figure 3 . This is a common analysis method for analog circuit diagrams and will not be elaborated further.

[0039] Figure 4 shows the influence of the aperture r of the first sound hole 23 p on the low-frequency response of the bone conduction microphone with high-frequency enhancement. It can be seen that as the aperture of the first sound hole 23 becomes larger, the low-frequency attenuation of the bone conduction microphone with high-frequency enhancement is more complete.

[0040] In summary, the present invention proposes a structural design of a bone conduction microphone with high-frequency enhancement. Through cavity structures such as the front cavity and the air gap, a resonance peak with a resonance frequency in the high frequency is formed to achieve the effect of enhancing the high-frequency frequency response.

[0041] This application also discloses a method for bone conduction sound transmission with high-frequency enhancement, including the following steps:

[0042] Step 1, when a human body makes a sound, the bone conduction microphone contacts the human head bone and receives a vibration signal, causing the diaphragm (22) to vibrate under excitation;

[0043] Step 2, after the diaphragm (22) vibrates, a sound pressure change is formed under the combined action of the front cavity (11) and the air gap (12);

[0044] Step 3, the MEMS microphone (24) obtains the sound pressure change and converts it into an electrical signal;

[0045] Step 4, the ASIC chip (21) processes the electrical signal and outputs a sound signal with high-frequency enhancement.

[0046] A bone conduction microphone with high-frequency enhancement disclosed by the present invention can be applied to the structural design of a bone conduction microphone with a high-frequency frequency response enhancement effect, and is also applicable to the structural design of related devices of a bone conduction microphone with a high-frequency frequency response enhancement effect.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications or equivalent replacements can still be made to the specific implementation manners of the present invention, and any modification or equivalent replacement without departing from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A high-frequency enhanced bone conduction microphone, comprising a housing, and an ASIC chip, a diaphragm, and a MEMS microphone disposed within the housing; characterized in that: The bone conduction microphone further includes a perforated plate, the diaphragm is disposed in the middle of the bone conduction microphone, the perforated plate is installed below the diaphragm, and the diaphragm and the perforated plate divide the housing space into three regions. Among them, the space above the diaphragm constitutes the front cavity of the bone conduction microphone, the space below the perforated plate constitutes the back cavity, and the space between the diaphragm and the perforated plate constitutes the air gap; The ASIC chip and the MEMS microphone are disposed above the diaphragm, and a first sound hole is opened on the surface of the MEMS microphone; an opening is provided on the diaphragm directly below the MEMS microphone, so that the back surface of the MEMS microphone is connected to the air gap; a second sound hole is opened on the perforated plate, and a mass is installed below the diaphragm, and the diaphragm and the mass form a spring oscillator structure.

2. The high-frequency enhanced bone conduction microphone according to claim 1, characterized in that: The diaphragm is made of an elastic polymer.

3. The high-frequency enhanced bone conduction microphone according to claim 1, characterized in that: The mass is made of a metal material.

4. The high-frequency enhanced bone conduction microphone according to claim 1, characterized in that: When the mass is located below the opening of the diaphragm, an opening needs to be made at the corresponding position of the mass to avoid the mass blocking the opening of the diaphragm.

5. The high-frequency enhanced bone conduction microphone according to claim 1 or 3, characterized in that: The diameter of the first sound hole is less than 10 μm.

6. The high-frequency enhanced bone conduction microphone according to claim 5, characterized in that: As the aperture of the first sound hole becomes larger, the low-frequency attenuation of the high-frequency enhanced bone conduction microphone is more sufficient.

7. The high-frequency enhanced bone conduction microphone according to claim 1, characterized in that: When the number of the second sound holes opened on the perforated plate is multiple, the second sound holes are evenly distributed on the perforated plate, and the second sound holes are used to attenuate the amplitude of the mechanical resonance peak of the output signal.

8. A sound transmission method using the high-frequency enhanced bone conduction microphone according to any one of claims 1-7, characterized in that, Including the following steps: Step 1, the bone conduction microphone receives a vibration signal, so that the diaphragm vibrates under excitation; Step 2, after the diaphragm vibrates, a sound pressure change is formed under the combined action of the front cavity and the air gap; Step 3, the MEMS microphone obtains the sound pressure change and converts it into an electrical signal; Step 4, the ASIC chip processes the electrical signal and outputs a high-frequency enhanced sound signal.

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