Barrier structure for microphone

Abstract

The present invention provides a shield structure for a microphone, comprising: a housing; a duct; and a cavity connected to the duct. The duct and cavity are located within the housing, the cavity being located on the side opposite the duct opening. A porous structure is located within the cavity, which is positioned between the duct and the microphone. The present invention aims to provide a shield structure for a microphone that reduces wind noise picked up by the microphone.

Description

Technical Field

[0001] An embodiment of the present invention relates to a barrier structure for a microphone. Background Art

[0002] Microphones are widely used in mobile electronic devices such as mobile phones and headphones and are a core component for phone calls. The basic principle is that microphones pick up the human voice and ambient signals, transmit them to the system, and then conduct the call. However, during this process, the microphone also picks up wind noise, which can degrade call quality.

[0003] There are various design methods for suppressing wind noise picked up by microphones. Their purpose is to reduce the amount of wind noise picked up by the microphone, thereby improving call quality. A common method currently employed is to place a barrier structure in front of the microphone's sound inlet. When wind noise passes through this structure, it is attenuated, resulting in a smaller amount of wind noise picked up by the microphone.

[0004] Most common methods for suppressing wind noise picked up by microphones don't perform very well. This is because they don't consider the fundamental mechanisms of wind noise generation during their design. Most barrier structures don't actually effectively reduce wind noise and may even cause loss of acoustic signal transmission. Summary of the Invention

[0005] In view of the problems existing in the related art, an object of the present invention is to provide a barrier structure for a microphone to reduce the noise picked up by the microphone.

[0006] To achieve the above-mentioned objectives, the present invention provides a barrier structure for a microphone, comprising: a shell; a pipe and a cavity connected to the pipe, the pipe and the cavity are located in the shell, the cavity is located on the side opposite to the opening of the pipe, the porous structure is located in the cavity, and the cavity is located between the pipe and the microphone.

[0007] In some embodiments, the porous structure is a foam.

[0008] In some embodiments, the cross-section of the tube increases as it approaches the cavity.

[0009] In some embodiments, the porous structure has a wedge structure facing the conduit.

[0010] In some embodiments, the porous structure has one or more layers of wedge structures.

[0011] In some embodiments, the conduit has a bend.

[0012] In some embodiments, the pipeline includes a main pipe and a branch pipe located around the main pipe, and the main pipe is communicated with the branch pipe.

[0013] In some embodiments, the pipe wall of the main pipe and the shell form a branch pipe, a hole is provided on the pipe wall of the main pipe, and the baffle is located on a side of the hole close to the cavity.

[0014] In some embodiments, the baffle extends from the tube wall toward the opening to form an acute angle with the tube wall.

[0015] In some embodiments, the microphone is located on a circuit board and is in direct contact with the porous structure in the cavity, and the circuit board is connected to the housing. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Various aspects of the present invention will be best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be noted that, in accordance with standard practice in the industry, the various components are not drawn to scale. In fact, the dimensions of the various components may be arbitrarily increased or decreased for clarity of discussion.

[0017] Figures 1 to 10 Schematic diagrams of the structure of a barrier structure for a microphone according to different embodiments of the present application are shown. DETAILED DESCRIPTION

[0018] In order to better understand the spirit of the embodiments of the present application, some preferred embodiments of the present application are further described below.

[0019] The embodiments of the present application will be described in detail below. Throughout this specification, identical or similar components and components having identical or similar functions are represented by similar reference numerals. The embodiments described herein with respect to the accompanying drawings are illustrative and diagrammatic and are intended to provide a basic understanding of the present application. The embodiments of the present application should not be construed as limiting the present application.

[0020] As used herein, the terms "substantially," "substantially," and "approximately" are used to describe and illustrate small variations. When used in conjunction with an event or circumstance, the terms may refer to instances where the event or circumstance occurred precisely as well as instances where the event or circumstance occurred very approximately. For example, when used in conjunction with a numerical value, the terms may refer to a range of variation of less than or equal to ±10% of the numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. For example, two values ​​may be considered “substantially” the same if the difference between them is less than or equal to ±10% of the mean of the values ​​(e.g., less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%).

[0021] In this specification, unless otherwise specified or limited, relative terms such as "central", "longitudinal", "lateral", "front", "rear", "right", "left", "inner", "outer", "lower", "higher", "horizontal", "vertical", "above", "below", "above", "below", "top", "bottom" and their derivatives (such as "horizontally", "downwardly", "upwardly", etc.) should be interpreted as referring to the directions described in the discussion or depicted in the drawings. These relative terms are only used for convenience of description and do not require that the present application be constructed or operated in a specific orientation.

[0022] In addition, amounts, ratios, and other numerical values ​​are sometimes presented herein in a range format. It should be understood that such a range format is used for convenience and brevity and should be interpreted flexibly to include not only the values ​​explicitly specified as limits of the range, but also all individual values ​​or sub-ranges encompassed within the range, as if each value and sub-range were explicitly specified.

[0023] Furthermore, for ease of description, “first,” “second,” “third,” etc. may be used herein to distinguish different components in a figure or a series of figures. “First,” “second,” “third,” etc. are not intended to describe the corresponding components.

[0024] The principle of wind noise picked up by a microphone involves fluid mechanics and aeroacoustics. In fact, when a microphone picks up wind noise, what is collected is not the sound signal, but the disturbance of the microphone diaphragm caused by air turbulence. Research on structures that suppress wind noise picked up by microphones can be traced back to the 1980s. M. Strasberg proposed a sound barrier structure placed outside the microphone to suppress wind noise. Through dimensional analysis, several factors affecting wind noise suppression were discussed, including wind speed, size and shape of the sound barrier. The following formula was derived to calculate the size of the wind noise picked up by the microphone:

[0025] L s =67+63logV-33logf-23logD

[0026] Where V is the flow velocity, f is the frequency, and D is the diameter of the sound barrier. However, M. Strasberg's research and conclusions only apply to conditions with low wind speeds. These conclusions do not apply when the wind speed is high and the air turbulence is intense. Scott Morgan studied the causes of wind noise at high flow rates. He proposed that, based on Bernoulli's theory, pressure fluctuations in laminar flow are related to the kinetic energy of the fluid. At high flow rates, the total air pressure is:

[0027] p=0.5ρ(μ+V)2=0.5ρ(V2+μ2+2μV)

[0028] Where μ is the fluctuation velocity, V is the average velocity, and ρ is the gas density. At high flow rates, the fluctuation velocity is typically 5%-15% of the average velocity, so the value of the above equation is primarily determined by the third term: p = ρμV. Therefore, Scott Morgan believes that at high flow rates, wind noise primarily originates from turbulent pressure disturbances in the airflow. Furthermore, through experiments, he concluded that wind barriers are ineffective at reducing wind noise at high flow rates.

[0029] GPVan Den Berg studied both low and high flow rates. He proposed that at low velocities, the wind noise picked up by microphones primarily originates from vortices generated by the interaction of the airflow and wind barriers. At high velocities, however, wind noise originates from the turbulence inherent in the airflow. While wind barriers effectively suppress wind noise at low velocities, their effectiveness is less pronounced at high velocities.

[0030] Most current designs for suppressing wind noise picked up by microphones are not based on the mechanism of wind noise generation, and therefore are ineffective. For example, some designs add a duct in front of the microphone to suppress wind noise, but this does not suppress wind noise at high flow rates. Instead, it increases the vortex in the airflow, thereby enhancing wind noise. There are also some designs that use a cavity plus a small hole. Although this can reduce wind noise, it does not take into account the poor wind barrier effect at high wind speeds. It also does not take into account the acoustic signal transmission loss caused by the cavity, causing the sound picked up by the microphone to be distorted at high frequencies.

[0031] According to the principle described above, the sound barrier has a good suppression effect on wind noise at low flow rates, but has little effect at high flow rates. Figure 1 The barrier structure 100 of the present invention consists of two parts: a duct 10 and a cavity 12. When airflow A passes through the barrier structure 100, it first passes through the duct 10, where its velocity is reduced due to the viscosity of the duct 10. Airflow A then continues into the cavity 12, which is filled with a porous structure (e.g., foam) to act as a sound barrier. Before airflow A reaches the microphone 14, its velocity and wind noise are effectively suppressed.

[0032] See also Figure 2An embodiment of the present application provides a barrier structure 100 for a microphone 14, comprising: a shell 20; a duct 10 and a cavity 12 connected to the duct 10, the duct 10 and the cavity 12 being located in the shell 20, the cavity 12 being located on the side opposite to the opening 22 (sound inlet) of the duct 10, the porous structure 24 being located in the cavity 12, and the cavity 12 being located between the duct 10 and the microphone 14. In some embodiments, the porous structure 24 is foam or sound-absorbing cotton. In some embodiments, the airflow A enters the barrier structure 100 from the opening 22. In some embodiments, the microphone 14 is located on a circuit board 18 and is in direct contact with the porous structure 24 in the cavity 12, and the circuit board 18 is connected to the shell 20. The viscous effect of the wall of the duct 10 reduces the wind speed. In some embodiments, the wall of the duct 10 is formed by part of the shell 20.

[0033] In some embodiments, the cross-sectional area (CSV) of the conduit 10 increases as it approaches the cavity 12. According to the law of conservation of matter, the volumetric flow rate within the conduit 10 is constant everywhere: V1*S01=V2*S02. Therefore, a larger cross-sectional area (CSV) (S0) corresponds to a lower flow rate. Therefore, in embodiments of the present invention, the conduit 10 with a continuously increasing cross-sectional area (CSV) (S0) can more effectively reduce the flow rate of the airflow A.

[0034] See also Figures 3 to 10 In some embodiments, the porous structure 24 has a wedge structure 30 facing the pipe. In some embodiments, the wedge structure 30 can be a conical structure or a pyramidal structure. In some embodiments, the porous structure 24 has one or more layers of wedge structures 30. According to the wind noise reduction principle described above, the porous structure 24 is used as a wind barrier. The larger the surface area of ​​the wind barrier, the better the effect of reducing wind noise. The wedge structure 30 can significantly increase the contact surface area between the porous structure 24 and the airflow A, thereby improving the ability to reduce wind noise. The multi-layer wedge structure 30 further increases the surface area of ​​the airflow A and the wind barrier, further improving the ability to reduce wind noise.

[0035] See also Figures 6 to 8 In some embodiments, the pipe 10 has a bent portion 60 .

[0036] See also Figures 9 and 10 In some embodiments, the duct 10 includes a main pipe 90 and a branch pipe 92 disposed around the main pipe 90, the main pipe 90 communicating with the branch pipe 92. In some embodiments, a wall 94 of the main pipe 90 and the housing 20 form the branch pipe 92. The wall 94 of the main pipe 90 has a hole 96, and a baffle 98 is located on a side of the hole 96 that is adjacent to the cavity 12. In some embodiments, the baffle 98 extends from the wall 94 toward the opening 22 to form an acute angle with the wall 94, thereby guiding the airflow A. Figure 10 A schematic diagram illustrates the flow of airflow A through main pipe 90 and branch pipe 92. Due to the action of diversion baffle 98, airflow A is partially diverted to branch pipe 92, helping to reduce the flow rate of the gas in main pipe 90. The flow rate of branch pipe 92 also gradually decreases due to the action of the branch pipe itself. As a result, the flow rates of the airflows in both pipes are further reduced when they reach cavity 12.

[0037] A wind noise test experiment was conducted based on the structure of the present invention. The air flow A was provided by the air duct, the distance between the opening 22 and the outlet of the air duct was 30 cm, and the gas flow rate at the opening 22 was 7 m / s. The microphone 14 collected the signal and performed spectrum analysis. Three groups of comparative experiments were conducted: the control group 1 had only a microphone and no barrier structure; the control group 2 had a microphone and a traditional barrier structure with only a pipe design located in front of the microphone; the control group 3 had a microphone and the barrier structure 100 of the embodiment of the present application. According to the experimental results, compared with the signals collected by the control groups 1 and 2, the wind noise collected by the microphone of the control group 3 was significantly suppressed. However, the wind noise picked up by the microphone of the control group 2 increased instead of decreased compared with that of the control group 1. The shape of the cavity 12 in the barrier structure 100 of the embodiment of the present invention is not limited.

[0038] According to experimental simulation, the diameter of the pipe 10 of the present invention is between 0.6mm and 1.0mm. Since the diameter of the pipe 10 is very small, the viscosity of the pipe wall will react strongly with the airflow A, thereby reducing the flow rate of the airflow. Finite element simulation is performed based on COMSOL to verify the influence of the pipe on the flow rate. Assume that the average flow rate of the incident airflow A is 10m / s. After the airflow A passes through the pipe, it can be obtained that the flow rate decays rapidly. At the outlet section (i.e., reaching the cavity 12), the average flow rate of the airflow A is 4m / s. For the pipe 10, this application does not limit the shape of the pipe 10. Straight pipes and curved pipes are within the scope of the structure of the present invention. The cross-section of the pipe 10 is also not limited, and it can be circular, square or polygonal. The radius of the pipe 10 of the present application is preferably within 1mm.

[0039] When the microphone 14 and the barrier structure 100 of the present invention are used together, an acoustic channel is formed. This channel can suppress the microphone 14 from picking up wind noise, while also ensuring that the microphone can receive normal sound signals. a Harmony quality M a They are:

[0040]

[0041] Where V is the volume of the cavity 12 of the barrier structure 100 of the present invention, ρ0 is the density of the air flow A, and c0 is the speed of sound in the air. L is the length of the pipe 10 of the barrier structure 100 of the present invention. S0 is the equivalent cross-sectional area of ​​the pipe 10 of the barrier structure 100 of the present invention. a Harmony C a It forms a low-pass filter. Its cut-off frequency is:

[0042]

[0043] In the actual use of the product, in order to ensure the quality of the call, the microphone 14 needs to pick up the sound without distortion within 8000 Hz. Therefore, the design index of the structure size of the barrier structure 100 needs to meet the following requirements:

[0044]

[0045] Then we get:

[0046]

[0047] Wherein, V is the volume of the cavity 12 of the barrier structure 100 of the present invention; L is the length of the pipe 10 of the barrier structure 100 of the present invention; in the embodiment where the cross-section CSV of the pipe 10 is circular, d is the equivalent diameter of the pipe 10 of the barrier structure 100 of the present invention.

[0048] The barrier structure 100 of the present invention can further include various variations in the design of the duct 10 and cavity 12, such as variations in the duct 10 diameter, internal material, and the shape and arrangement of the partition walls and porous materials. The barrier structure 100 of the present invention allows the microphone 14 to effectively reduce wind noise while maintaining call quality.

[0049] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A barrier structure for a microphone, characterized in that include: case; A pipe and a cavity connected to the pipe are located in the housing, the cavity is located on a side opposite to the opening of the pipe, a porous structure is located in the cavity, and the cavity is located between the pipe and the microphone; wherein the cross section of the duct increases along a direction from the opening to the cavity, and the cross section of the cavity increases along a direction from the duct to the microphone; wherein the cross section of the porous structure near the microphone is larger than the cross section of the porous structure near the pipe; Wherein, the porous structure is adjacent to the microphone.

2. The barrier structure for a microphone according to claim 1, characterized in that The porous structure is foam.

3. The barrier structure for a microphone according to claim 1 or 2, characterized in that: The porous structure has a wedge structure facing the pipe.

4. The barrier structure for a microphone according to claim 3, characterized in that The porous structure has one or more layers of the wedge structure.

5. The barrier structure for a microphone according to claim 3, characterized in that The pipe has a bent portion.

6. The barrier structure for a microphone according to claim 3, characterized in that The pipeline includes a main pipe and a branch pipe located around the main pipe, and the main pipe is communicated with the branch pipe.

7. The barrier structure for a microphone according to claim 6, characterized in that The pipe wall of the main pipe and the shell form the side branch pipe. A hole is provided on the pipe wall of the main pipe, and a baffle is located on a side of the hole close to the cavity.

8. The barrier structure for a microphone according to claim 7, characterized in that The baffle extends from the tube wall toward the opening to form an acute angle with the tube wall.

9. The barrier structure for a microphone according to claim 1, characterized in that The microphone is located on a circuit board and is in direct contact with the porous structure in the cavity. The circuit board is connected to the housing.

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